File: //usr/lib/python3/dist-packages/pg.py
#!/usr/bin/python
#
# PyGreSQL - a Python interface for the PostgreSQL database.
#
# This file contains the classic pg module.
#
# Copyright (c) 2020 by the PyGreSQL Development Team
#
# The notification handler is based on pgnotify which is
# Copyright (c) 2001 Ng Pheng Siong. All rights reserved.
#
# Please see the LICENSE.TXT file for specific restrictions.
"""PyGreSQL classic interface.
This pg module implements some basic database management stuff.
It includes the _pg module and builds on it, providing the higher
level wrapper class named DB with additional functionality.
This is known as the "classic" ("old style") PyGreSQL interface.
For a DB-API 2 compliant interface use the newer pgdb module.
"""
from __future__ import print_function, division
try:
from _pg import *
except ImportError:
import os
import sys
# see https://docs.python.org/3/whatsnew/3.8.html#ctypes
if os.name == 'nt' and sys.version_info >= (3, 8):
for path in os.environ["PATH"].split(os.pathsep):
if os.path.exists(os.path.join(path, 'libpq.dll')):
with os.add_dll_directory(os.path.abspath(path)):
from _pg import *
break
else:
raise
else:
raise
__version__ = version
__all__ = [
'DB', 'Adapter',
'NotificationHandler', 'Typecasts',
'Bytea', 'Hstore', 'Json', 'Literal',
'Error', 'Warning',
'DataError', 'DatabaseError',
'IntegrityError', 'InterfaceError', 'InternalError',
'InvalidResultError', 'MultipleResultsError',
'NoResultError', 'NotSupportedError',
'OperationalError', 'ProgrammingError',
'INV_READ', 'INV_WRITE',
'SEEK_CUR', 'SEEK_END', 'SEEK_SET',
'TRANS_ACTIVE', 'TRANS_IDLE', 'TRANS_INERROR',
'TRANS_INTRANS', 'TRANS_UNKNOWN',
'cast_array', 'cast_hstore', 'cast_record',
'connect', 'escape_bytea', 'escape_string', 'unescape_bytea',
'get_array', 'get_bool', 'get_bytea_escaped',
'get_datestyle', 'get_decimal', 'get_decimal_point',
'get_defbase', 'get_defhost', 'get_defopt', 'get_defport', 'get_defuser',
'get_jsondecode',
'set_array', 'set_bool', 'set_bytea_escaped',
'set_datestyle', 'set_decimal', 'set_decimal_point',
'set_defbase', 'set_defhost', 'set_defopt',
'set_defpasswd', 'set_defport', 'set_defuser',
'set_jsondecode', 'set_query_helpers',
'version', '__version__']
import select
import warnings
import weakref
from datetime import date, time, datetime, timedelta, tzinfo
from decimal import Decimal
from math import isnan, isinf
from collections import namedtuple
from keyword import iskeyword
from operator import itemgetter
from functools import partial
from re import compile as regex
from json import loads as jsondecode, dumps as jsonencode
from uuid import UUID
try: # noinspection PyUnresolvedReferences
long
except NameError: # Python >= 3.0
long = int
try: # noinspection PyUnresolvedReferences
basestring
except NameError: # Python >= 3.0
basestring = (str, bytes)
try:
from functools import lru_cache
except ImportError: # Python < 3.2
from functools import update_wrapper
try:
from _thread import RLock
except ImportError:
class RLock: # for builds without threads
def __enter__(self): pass
def __exit__(self, exctype, excinst, exctb): pass
def lru_cache(maxsize=128):
"""Simplified functools.lru_cache decorator for one argument."""
def decorator(function):
sentinel = object()
cache = {}
get = cache.get
lock = RLock()
root = []
root_full = [root, False]
root[:] = [root, root, None, None]
if maxsize == 0:
def wrapper(arg):
res = function(arg)
return res
elif maxsize is None:
def wrapper(arg):
res = get(arg, sentinel)
if res is not sentinel:
return res
res = function(arg)
cache[arg] = res
return res
else:
def wrapper(arg):
with lock:
link = get(arg)
if link is not None:
root = root_full[0]
prev, next, _arg, res = link
prev[1] = next
next[0] = prev
last = root[0]
last[1] = root[0] = link
link[0] = last
link[1] = root
return res
res = function(arg)
with lock:
root, full = root_full
if arg in cache:
pass
elif full:
oldroot = root
oldroot[2] = arg
oldroot[3] = res
root = root_full[0] = oldroot[1]
oldarg = root[2]
oldres = root[3] # keep reference
root[2] = root[3] = None
del cache[oldarg]
cache[arg] = oldroot
else:
last = root[0]
link = [last, root, arg, res]
last[1] = root[0] = cache[arg] = link
if len(cache) >= maxsize:
root_full[1] = True
return res
wrapper.__wrapped__ = function
return update_wrapper(wrapper, function)
return decorator
# Auxiliary classes and functions that are independent from a DB connection:
try:
from collections import OrderedDict
except ImportError: # Python 2.6 or 3.0
OrderedDict = dict
class AttrDict(dict):
"""Simple read-only ordered dictionary for storing attribute names."""
def __init__(self, *args, **kw):
if len(args) > 1 or kw:
raise TypeError
items = args[0] if args else []
if isinstance(items, dict):
raise TypeError
items = list(items)
self._keys = [item[0] for item in items]
dict.__init__(self, items)
self._read_only = True
error = self._read_only_error
self.clear = self.update = error
self.pop = self.setdefault = self.popitem = error
def __setitem__(self, key, value):
if self._read_only:
self._read_only_error()
dict.__setitem__(self, key, value)
def __delitem__(self, key):
if self._read_only:
self._read_only_error()
dict.__delitem__(self, key)
def __iter__(self):
return iter(self._keys)
def keys(self):
return list(self._keys)
def values(self):
return [self[key] for key in self]
def items(self):
return [(key, self[key]) for key in self]
def iterkeys(self):
return self.__iter__()
def itervalues(self):
return iter(self.values())
def iteritems(self):
return iter(self.items())
@staticmethod
def _read_only_error(*args, **kw):
raise TypeError('This object is read-only')
else:
class AttrDict(OrderedDict):
"""Simple read-only ordered dictionary for storing attribute names."""
def __init__(self, *args, **kw):
self._read_only = False
OrderedDict.__init__(self, *args, **kw)
self._read_only = True
error = self._read_only_error
self.clear = self.update = error
self.pop = self.setdefault = self.popitem = error
def __setitem__(self, key, value):
if self._read_only:
self._read_only_error()
OrderedDict.__setitem__(self, key, value)
def __delitem__(self, key):
if self._read_only:
self._read_only_error()
OrderedDict.__delitem__(self, key)
@staticmethod
def _read_only_error(*args, **kw):
raise TypeError('This object is read-only')
try:
from inspect import signature
except ImportError: # Python < 3.3
from inspect import getargspec
def get_args(func):
return getargspec(func).args
else:
def get_args(func):
return list(signature(func).parameters)
try:
from datetime import timezone
except ImportError: # Python < 3.2
class timezone(tzinfo):
"""Simple timezone implementation."""
def __init__(self, offset, name=None):
self.offset = offset
if not name:
minutes = self.offset.days * 1440 + self.offset.seconds // 60
if minutes < 0:
hours, minutes = divmod(-minutes, 60)
hours = -hours
else:
hours, minutes = divmod(minutes, 60)
name = 'UTC%+03d:%02d' % (hours, minutes)
self.name = name
def utcoffset(self, dt):
return self.offset
def tzname(self, dt):
return self.name
def dst(self, dt):
return None
timezone.utc = timezone(timedelta(0), 'UTC')
_has_timezone = False
else:
_has_timezone = True
# time zones used in Postgres timestamptz output
_timezones = dict(CET='+0100', EET='+0200', EST='-0500',
GMT='+0000', HST='-1000', MET='+0100', MST='-0700',
UCT='+0000', UTC='+0000', WET='+0000')
def _timezone_as_offset(tz):
if tz.startswith(('+', '-')):
if len(tz) < 5:
return tz + '00'
return tz.replace(':', '')
return _timezones.get(tz, '+0000')
def _get_timezone(tz):
tz = _timezone_as_offset(tz)
minutes = 60 * int(tz[1:3]) + int(tz[3:5])
if tz[0] == '-':
minutes = -minutes
return timezone(timedelta(minutes=minutes), tz)
def _oid_key(table):
"""Build oid key from a table name."""
return 'oid(%s)' % table
class _SimpleTypes(dict):
"""Dictionary mapping pg_type names to simple type names."""
_types = {'bool': 'bool',
'bytea': 'bytea',
'date': 'date interval time timetz timestamp timestamptz'
' abstime reltime', # these are very old
'float': 'float4 float8',
'int': 'cid int2 int4 int8 oid xid',
'hstore': 'hstore', 'json': 'json jsonb', 'uuid': 'uuid',
'num': 'numeric', 'money': 'money',
'text': 'bpchar char name text varchar'}
def __init__(self):
for typ, keys in self._types.items():
for key in keys.split():
self[key] = typ
self['_%s' % key] = '%s[]' % typ
# this could be a static method in Python > 2.6
def __missing__(self, key):
return 'text'
_simpletypes = _SimpleTypes()
def _quote_if_unqualified(param, name):
"""Quote parameter representing a qualified name.
Puts a quote_ident() call around the give parameter unless
the name contains a dot, in which case the name is ambiguous
(could be a qualified name or just a name with a dot in it)
and must be quoted manually by the caller.
"""
if isinstance(name, basestring) and '.' not in name:
return 'quote_ident(%s)' % (param,)
return param
class _ParameterList(list):
"""Helper class for building typed parameter lists."""
def add(self, value, typ=None):
"""Typecast value with known database type and build parameter list.
If this is a literal value, it will be returned as is. Otherwise, a
placeholder will be returned and the parameter list will be augmented.
"""
value = self.adapt(value, typ)
if isinstance(value, Literal):
return value
self.append(value)
return '$%d' % len(self)
class Bytea(bytes):
"""Wrapper class for marking Bytea values."""
class Hstore(dict):
"""Wrapper class for marking hstore values."""
_re_quote = regex('^[Nn][Uu][Ll][Ll]$|[ ,=>]')
@classmethod
def _quote(cls, s):
if s is None:
return 'NULL'
if not s:
return '""'
s = s.replace('"', '\\"')
if cls._re_quote.search(s):
s = '"%s"' % s
return s
def __str__(self):
q = self._quote
return ','.join('%s=>%s' % (q(k), q(v)) for k, v in self.items())
class Json:
"""Wrapper class for marking Json values."""
def __init__(self, obj):
self.obj = obj
class Literal(str):
"""Wrapper class for marking literal SQL values."""
class Adapter:
"""Class providing methods for adapting parameters to the database."""
_bool_true_values = frozenset('t true 1 y yes on'.split())
_date_literals = frozenset('current_date current_time'
' current_timestamp localtime localtimestamp'.split())
_re_array_quote = regex(r'[{},"\\\s]|^[Nn][Uu][Ll][Ll]$')
_re_record_quote = regex(r'[(,"\\]')
_re_array_escape = _re_record_escape = regex(r'(["\\])')
def __init__(self, db):
self.db = weakref.proxy(db)
@classmethod
def _adapt_bool(cls, v):
"""Adapt a boolean parameter."""
if isinstance(v, basestring):
if not v:
return None
v = v.lower() in cls._bool_true_values
return 't' if v else 'f'
@classmethod
def _adapt_date(cls, v):
"""Adapt a date parameter."""
if not v:
return None
if isinstance(v, basestring) and v.lower() in cls._date_literals:
return Literal(v)
return v
@staticmethod
def _adapt_num(v):
"""Adapt a numeric parameter."""
if not v and v != 0:
return None
return v
_adapt_int = _adapt_float = _adapt_money = _adapt_num
def _adapt_bytea(self, v):
"""Adapt a bytea parameter."""
return self.db.escape_bytea(v)
def _adapt_json(self, v):
"""Adapt a json parameter."""
if not v:
return None
if isinstance(v, basestring):
return v
return self.db.encode_json(v)
@classmethod
def _adapt_text_array(cls, v):
"""Adapt a text type array parameter."""
if isinstance(v, list):
adapt = cls._adapt_text_array
return '{%s}' % ','.join(adapt(v) for v in v)
if v is None:
return 'null'
if not v:
return '""'
v = str(v)
if cls._re_array_quote.search(v):
v = '"%s"' % cls._re_array_escape.sub(r'\\\1', v)
return v
_adapt_date_array = _adapt_text_array
@classmethod
def _adapt_bool_array(cls, v):
"""Adapt a boolean array parameter."""
if isinstance(v, list):
adapt = cls._adapt_bool_array
return '{%s}' % ','.join(adapt(v) for v in v)
if v is None:
return 'null'
if isinstance(v, basestring):
if not v:
return 'null'
v = v.lower() in cls._bool_true_values
return 't' if v else 'f'
@classmethod
def _adapt_num_array(cls, v):
"""Adapt a numeric array parameter."""
if isinstance(v, list):
adapt = cls._adapt_num_array
return '{%s}' % ','.join(adapt(v) for v in v)
if not v and v != 0:
return 'null'
return str(v)
_adapt_int_array = _adapt_float_array = _adapt_money_array = \
_adapt_num_array
def _adapt_bytea_array(self, v):
"""Adapt a bytea array parameter."""
if isinstance(v, list):
return b'{' + b','.join(
self._adapt_bytea_array(v) for v in v) + b'}'
if v is None:
return b'null'
return self.db.escape_bytea(v).replace(b'\\', b'\\\\')
def _adapt_json_array(self, v):
"""Adapt a json array parameter."""
if isinstance(v, list):
adapt = self._adapt_json_array
return '{%s}' % ','.join(adapt(v) for v in v)
if not v:
return 'null'
if not isinstance(v, basestring):
v = self.db.encode_json(v)
if self._re_array_quote.search(v):
v = '"%s"' % self._re_array_escape.sub(r'\\\1', v)
return v
def _adapt_record(self, v, typ):
"""Adapt a record parameter with given type."""
typ = self.get_attnames(typ).values()
if len(typ) != len(v):
raise TypeError('Record parameter %s has wrong size' % v)
adapt = self.adapt
value = []
for v, t in zip(v, typ):
v = adapt(v, t)
if v is None:
v = ''
elif not v:
v = '""'
else:
if isinstance(v, bytes):
if str is not bytes:
v = v.decode('ascii')
else:
v = str(v)
if self._re_record_quote.search(v):
v = '"%s"' % self._re_record_escape.sub(r'\\\1', v)
value.append(v)
return '(%s)' % ','.join(value)
def adapt(self, value, typ=None):
"""Adapt a value with known database type."""
if value is not None and not isinstance(value, Literal):
if typ:
simple = self.get_simple_name(typ)
else:
typ = simple = self.guess_simple_type(value) or 'text'
pg_str = getattr(value, '__pg_str__', None)
if pg_str:
value = pg_str(typ)
if simple == 'text':
pass
elif simple == 'record':
if isinstance(value, tuple):
value = self._adapt_record(value, typ)
elif simple.endswith('[]'):
if isinstance(value, list):
adapt = getattr(self, '_adapt_%s_array' % simple[:-2])
value = adapt(value)
else:
adapt = getattr(self, '_adapt_%s' % simple)
value = adapt(value)
return value
@staticmethod
def simple_type(name):
"""Create a simple database type with given attribute names."""
typ = DbType(name)
typ.simple = name
return typ
@staticmethod
def get_simple_name(typ):
"""Get the simple name of a database type."""
if isinstance(typ, DbType):
return typ.simple
return _simpletypes[typ]
@staticmethod
def get_attnames(typ):
"""Get the attribute names of a composite database type."""
if isinstance(typ, DbType):
return typ.attnames
return {}
_frequent_simple_types = {
Bytea: 'bytea',
str: 'text',
bytes: 'text',
bool: 'bool',
int: 'int',
long: 'int',
float: 'float',
Decimal: 'num',
date: 'date',
time: 'date',
datetime: 'date',
timedelta: 'date'
}
@classmethod
def guess_simple_type(cls, value):
"""Try to guess which database type the given value has."""
# optimize for most frequent types
try:
return cls._frequent_simple_types[type(value)]
except KeyError:
pass
if isinstance(value, Bytea):
return 'bytea'
if isinstance(value, basestring):
return 'text'
if isinstance(value, bool):
return 'bool'
if isinstance(value, (int, long)):
return 'int'
if isinstance(value, float):
return 'float'
if isinstance(value, Decimal):
return 'num'
if isinstance(value, (date, time, datetime, timedelta)):
return 'date'
if isinstance(value, list):
return '%s[]' % (cls.guess_simple_base_type(value) or 'text',)
if isinstance(value, tuple):
simple_type = cls.simple_type
guess = cls.guess_simple_type
def get_attnames(self):
return AttrDict((str(n + 1), simple_type(guess(v)))
for n, v in enumerate(value))
typ = simple_type('record')
typ._get_attnames = get_attnames
return typ
@classmethod
def guess_simple_base_type(cls, value):
"""Try to guess the base type of a given array."""
for v in value:
if isinstance(v, list):
typ = cls.guess_simple_base_type(v)
else:
typ = cls.guess_simple_type(v)
if typ:
return typ
def adapt_inline(self, value, nested=False):
"""Adapt a value that is put into the SQL and needs to be quoted."""
if value is None:
return 'NULL'
if isinstance(value, Literal):
return value
if isinstance(value, Bytea):
value = self.db.escape_bytea(value)
if bytes is not str: # Python >= 3.0
value = value.decode('ascii')
elif isinstance(value, Json):
if value.encode:
return value.encode()
value = self.db.encode_json(value)
elif isinstance(value, (datetime, date, time, timedelta)):
value = str(value)
if isinstance(value, basestring):
value = self.db.escape_string(value)
return "'%s'" % value
if isinstance(value, bool):
return 'true' if value else 'false'
if isinstance(value, float):
if isinf(value):
return "'-Infinity'" if value < 0 else "'Infinity'"
if isnan(value):
return "'NaN'"
return value
if isinstance(value, (int, long, Decimal)):
return value
if isinstance(value, list):
q = self.adapt_inline
s = '[%s]' if nested else 'ARRAY[%s]'
return s % ','.join(str(q(v, nested=True)) for v in value)
if isinstance(value, tuple):
q = self.adapt_inline
return '(%s)' % ','.join(str(q(v)) for v in value)
pg_repr = getattr(value, '__pg_repr__', None)
if not pg_repr:
raise InterfaceError(
'Do not know how to adapt type %s' % type(value))
value = pg_repr()
if isinstance(value, (tuple, list)):
value = self.adapt_inline(value)
return value
def parameter_list(self):
"""Return a parameter list for parameters with known database types.
The list has an add(value, typ) method that will build up the
list and return either the literal value or a placeholder.
"""
params = _ParameterList()
params.adapt = self.adapt
return params
def format_query(self, command, values=None, types=None, inline=False):
"""Format a database query using the given values and types."""
if not values:
return command, []
if inline and types:
raise ValueError('Typed parameters must be sent separately')
params = self.parameter_list()
if isinstance(values, (list, tuple)):
if inline:
adapt = self.adapt_inline
literals = [adapt(value) for value in values]
else:
add = params.add
if types:
if (not isinstance(types, (list, tuple)) or
len(types) != len(values)):
raise TypeError('The values and types do not match')
literals = [add(value, typ)
for value, typ in zip(values, types)]
else:
literals = [add(value) for value in values]
command %= tuple(literals)
elif isinstance(values, dict):
# we want to allow extra keys in the dictionary,
# so we first must find the values actually used in the command
used_values = {}
literals = dict.fromkeys(values, '')
for key in values:
del literals[key]
try:
command % literals
except KeyError:
used_values[key] = values[key]
literals[key] = ''
values = used_values
if inline:
adapt = self.adapt_inline
literals = dict((key, adapt(value))
for key, value in values.items())
else:
add = params.add
if types:
if not isinstance(types, dict):
raise TypeError('The values and types do not match')
literals = dict((key, add(values[key], types.get(key)))
for key in sorted(values))
else:
literals = dict((key, add(values[key]))
for key in sorted(values))
command %= literals
else:
raise TypeError('The values must be passed as tuple, list or dict')
return command, params
def cast_bool(value):
"""Cast a boolean value."""
if not get_bool():
return value
return value[0] == 't'
def cast_json(value):
"""Cast a JSON value."""
cast = get_jsondecode()
if not cast:
return value
return cast(value)
def cast_num(value):
"""Cast a numeric value."""
return (get_decimal() or float)(value)
def cast_money(value):
"""Cast a money value."""
point = get_decimal_point()
if not point:
return value
if point != '.':
value = value.replace(point, '.')
value = value.replace('(', '-')
value = ''.join(c for c in value if c.isdigit() or c in '.-')
return (get_decimal() or float)(value)
def cast_int2vector(value):
"""Cast an int2vector value."""
return [int(v) for v in value.split()]
def cast_date(value, connection):
"""Cast a date value."""
# The output format depends on the server setting DateStyle. The default
# setting ISO and the setting for German are actually unambiguous. The
# order of days and months in the other two settings is however ambiguous,
# so at least here we need to consult the setting to properly parse values.
if value == '-infinity':
return date.min
if value == 'infinity':
return date.max
value = value.split()
if value[-1] == 'BC':
return date.min
value = value[0]
if len(value) > 10:
return date.max
fmt = connection.date_format()
return datetime.strptime(value, fmt).date()
def cast_time(value):
"""Cast a time value."""
fmt = '%H:%M:%S.%f' if len(value) > 8 else '%H:%M:%S'
return datetime.strptime(value, fmt).time()
_re_timezone = regex('(.*)([+-].*)')
def cast_timetz(value):
"""Cast a timetz value."""
tz = _re_timezone.match(value)
if tz:
value, tz = tz.groups()
else:
tz = '+0000'
fmt = '%H:%M:%S.%f' if len(value) > 8 else '%H:%M:%S'
if _has_timezone:
value += _timezone_as_offset(tz)
fmt += '%z'
return datetime.strptime(value, fmt).timetz()
return datetime.strptime(value, fmt).timetz().replace(
tzinfo=_get_timezone(tz))
def cast_timestamp(value, connection):
"""Cast a timestamp value."""
if value == '-infinity':
return datetime.min
if value == 'infinity':
return datetime.max
value = value.split()
if value[-1] == 'BC':
return datetime.min
fmt = connection.date_format()
if fmt.endswith('-%Y') and len(value) > 2:
value = value[1:5]
if len(value[3]) > 4:
return datetime.max
fmt = ['%d %b' if fmt.startswith('%d') else '%b %d',
'%H:%M:%S.%f' if len(value[2]) > 8 else '%H:%M:%S', '%Y']
else:
if len(value[0]) > 10:
return datetime.max
fmt = [fmt, '%H:%M:%S.%f' if len(value[1]) > 8 else '%H:%M:%S']
return datetime.strptime(' '.join(value), ' '.join(fmt))
def cast_timestamptz(value, connection):
"""Cast a timestamptz value."""
if value == '-infinity':
return datetime.min
if value == 'infinity':
return datetime.max
value = value.split()
if value[-1] == 'BC':
return datetime.min
fmt = connection.date_format()
if fmt.endswith('-%Y') and len(value) > 2:
value = value[1:]
if len(value[3]) > 4:
return datetime.max
fmt = ['%d %b' if fmt.startswith('%d') else '%b %d',
'%H:%M:%S.%f' if len(value[2]) > 8 else '%H:%M:%S', '%Y']
value, tz = value[:-1], value[-1]
else:
if fmt.startswith('%Y-'):
tz = _re_timezone.match(value[1])
if tz:
value[1], tz = tz.groups()
else:
tz = '+0000'
else:
value, tz = value[:-1], value[-1]
if len(value[0]) > 10:
return datetime.max
fmt = [fmt, '%H:%M:%S.%f' if len(value[1]) > 8 else '%H:%M:%S']
if _has_timezone:
value.append(_timezone_as_offset(tz))
fmt.append('%z')
return datetime.strptime(' '.join(value), ' '.join(fmt))
return datetime.strptime(' '.join(value), ' '.join(fmt)).replace(
tzinfo=_get_timezone(tz))
_re_interval_sql_standard = regex(
'(?:([+-])?([0-9]+)-([0-9]+) ?)?'
'(?:([+-]?[0-9]+)(?!:) ?)?'
'(?:([+-])?([0-9]+):([0-9]+):([0-9]+)(?:\\.([0-9]+))?)?')
_re_interval_postgres = regex(
'(?:([+-]?[0-9]+) ?years? ?)?'
'(?:([+-]?[0-9]+) ?mons? ?)?'
'(?:([+-]?[0-9]+) ?days? ?)?'
'(?:([+-])?([0-9]+):([0-9]+):([0-9]+)(?:\\.([0-9]+))?)?')
_re_interval_postgres_verbose = regex(
'@ ?(?:([+-]?[0-9]+) ?years? ?)?'
'(?:([+-]?[0-9]+) ?mons? ?)?'
'(?:([+-]?[0-9]+) ?days? ?)?'
'(?:([+-]?[0-9]+) ?hours? ?)?'
'(?:([+-]?[0-9]+) ?mins? ?)?'
'(?:([+-])?([0-9]+)(?:\\.([0-9]+))? ?secs?)? ?(ago)?')
_re_interval_iso_8601 = regex(
'P(?:([+-]?[0-9]+)Y)?'
'(?:([+-]?[0-9]+)M)?'
'(?:([+-]?[0-9]+)D)?'
'(?:T(?:([+-]?[0-9]+)H)?'
'(?:([+-]?[0-9]+)M)?'
'(?:([+-])?([0-9]+)(?:\\.([0-9]+))?S)?)?')
def cast_interval(value):
"""Cast an interval value."""
# The output format depends on the server setting IntervalStyle, but it's
# not necessary to consult this setting to parse it. It's faster to just
# check all possible formats, and there is no ambiguity here.
m = _re_interval_iso_8601.match(value)
if m:
m = [d or '0' for d in m.groups()]
secs_ago = m.pop(5) == '-'
m = [int(d) for d in m]
years, mons, days, hours, mins, secs, usecs = m
if secs_ago:
secs = -secs
usecs = -usecs
else:
m = _re_interval_postgres_verbose.match(value)
if m:
m, ago = [d or '0' for d in m.groups()[:8]], m.group(9)
secs_ago = m.pop(5) == '-'
m = [-int(d) for d in m] if ago else [int(d) for d in m]
years, mons, days, hours, mins, secs, usecs = m
if secs_ago:
secs = - secs
usecs = -usecs
else:
m = _re_interval_postgres.match(value)
if m and any(m.groups()):
m = [d or '0' for d in m.groups()]
hours_ago = m.pop(3) == '-'
m = [int(d) for d in m]
years, mons, days, hours, mins, secs, usecs = m
if hours_ago:
hours = -hours
mins = -mins
secs = -secs
usecs = -usecs
else:
m = _re_interval_sql_standard.match(value)
if m and any(m.groups()):
m = [d or '0' for d in m.groups()]
years_ago = m.pop(0) == '-'
hours_ago = m.pop(3) == '-'
m = [int(d) for d in m]
years, mons, days, hours, mins, secs, usecs = m
if years_ago:
years = -years
mons = -mons
if hours_ago:
hours = -hours
mins = -mins
secs = -secs
usecs = -usecs
else:
raise ValueError('Cannot parse interval: %s' % value)
days += 365 * years + 30 * mons
return timedelta(days=days, hours=hours, minutes=mins,
seconds=secs, microseconds=usecs)
class Typecasts(dict):
"""Dictionary mapping database types to typecast functions.
The cast functions get passed the string representation of a value in
the database which they need to convert to a Python object. The
passed string will never be None since NULL values are already
handled before the cast function is called.
Note that the basic types are already handled by the C extension.
They only need to be handled here as record or array components.
"""
# the default cast functions
# (str functions are ignored but have been added for faster access)
defaults = {'char': str, 'bpchar': str, 'name': str,
'text': str, 'varchar': str,
'bool': cast_bool, 'bytea': unescape_bytea,
'int2': int, 'int4': int, 'serial': int, 'int8': long, 'oid': int,
'hstore': cast_hstore, 'json': cast_json, 'jsonb': cast_json,
'float4': float, 'float8': float,
'numeric': cast_num, 'money': cast_money,
'date': cast_date, 'interval': cast_interval,
'time': cast_time, 'timetz': cast_timetz,
'timestamp': cast_timestamp, 'timestamptz': cast_timestamptz,
'int2vector': cast_int2vector, 'uuid': UUID,
'anyarray': cast_array, 'record': cast_record}
connection = None # will be set in a connection specific instance
def __missing__(self, typ):
"""Create a cast function if it is not cached.
Note that this class never raises a KeyError,
but returns None when no special cast function exists.
"""
if not isinstance(typ, str):
raise TypeError('Invalid type: %s' % typ)
cast = self.defaults.get(typ)
if cast:
# store default for faster access
cast = self._add_connection(cast)
self[typ] = cast
elif typ.startswith('_'):
base_cast = self[typ[1:]]
cast = self.create_array_cast(base_cast)
if base_cast:
self[typ] = cast
else:
attnames = self.get_attnames(typ)
if attnames:
casts = [self[v.pgtype] for v in attnames.values()]
cast = self.create_record_cast(typ, attnames, casts)
self[typ] = cast
return cast
@staticmethod
def _needs_connection(func):
"""Check if a typecast function needs a connection argument."""
try:
args = get_args(func)
except (TypeError, ValueError):
return False
else:
return 'connection' in args[1:]
def _add_connection(self, cast):
"""Add a connection argument to the typecast function if necessary."""
if not self.connection or not self._needs_connection(cast):
return cast
return partial(cast, connection=self.connection)
def get(self, typ, default=None):
"""Get the typecast function for the given database type."""
return self[typ] or default
def set(self, typ, cast):
"""Set a typecast function for the specified database type(s)."""
if isinstance(typ, basestring):
typ = [typ]
if cast is None:
for t in typ:
self.pop(t, None)
self.pop('_%s' % t, None)
else:
if not callable(cast):
raise TypeError("Cast parameter must be callable")
for t in typ:
self[t] = self._add_connection(cast)
self.pop('_%s' % t, None)
def reset(self, typ=None):
"""Reset the typecasts for the specified type(s) to their defaults.
When no type is specified, all typecasts will be reset.
"""
if typ is None:
self.clear()
else:
if isinstance(typ, basestring):
typ = [typ]
for t in typ:
self.pop(t, None)
@classmethod
def get_default(cls, typ):
"""Get the default typecast function for the given database type."""
return cls.defaults.get(typ)
@classmethod
def set_default(cls, typ, cast):
"""Set a default typecast function for the given database type(s)."""
if isinstance(typ, basestring):
typ = [typ]
defaults = cls.defaults
if cast is None:
for t in typ:
defaults.pop(t, None)
defaults.pop('_%s' % t, None)
else:
if not callable(cast):
raise TypeError("Cast parameter must be callable")
for t in typ:
defaults[t] = cast
defaults.pop('_%s' % t, None)
def get_attnames(self, typ):
"""Return the fields for the given record type.
This method will be replaced with the get_attnames() method of DbTypes.
"""
return {}
def dateformat(self):
"""Return the current date format.
This method will be replaced with the dateformat() method of DbTypes.
"""
return '%Y-%m-%d'
def create_array_cast(self, basecast):
"""Create an array typecast for the given base cast."""
cast_array = self['anyarray']
def cast(v):
return cast_array(v, basecast)
return cast
def create_record_cast(self, name, fields, casts):
"""Create a named record typecast for the given fields and casts."""
cast_record = self['record']
record = namedtuple(name, fields)
def cast(v):
return record(*cast_record(v, casts))
return cast
def get_typecast(typ):
"""Get the global typecast function for the given database type(s)."""
return Typecasts.get_default(typ)
def set_typecast(typ, cast):
"""Set a global typecast function for the given database type(s).
Note that connections cache cast functions. To be sure a global change
is picked up by a running connection, call db.db_types.reset_typecast().
"""
Typecasts.set_default(typ, cast)
class DbType(str):
"""Class augmenting the simple type name with additional info.
The following additional information is provided:
oid: the PostgreSQL type OID
pgtype: the internal PostgreSQL data type name
regtype: the registered PostgreSQL data type name
simple: the more coarse-grained PyGreSQL type name
typtype: b = base type, c = composite type etc.
category: A = Array, b = Boolean, C = Composite etc.
delim: delimiter for array types
relid: corresponding table for composite types
attnames: attributes for composite types
"""
@property
def attnames(self):
"""Get names and types of the fields of a composite type."""
return self._get_attnames(self)
class DbTypes(dict):
"""Cache for PostgreSQL data types.
This cache maps type OIDs and names to DbType objects containing
information on the associated database type.
"""
_num_types = frozenset('int float num money'
' int2 int4 int8 float4 float8 numeric money'.split())
def __init__(self, db):
"""Initialize type cache for connection."""
super(DbTypes, self).__init__()
self._db = weakref.proxy(db)
self._regtypes = False
self._typecasts = Typecasts()
self._typecasts.get_attnames = self.get_attnames
self._typecasts.connection = self._db
if db.server_version < 80400:
# older remote databases (not officially supported)
self._query_pg_type = (
"SELECT oid, typname, typname::text::regtype,"
" typtype, null as typcategory, typdelim, typrelid"
" FROM pg_catalog.pg_type"
" WHERE oid OPERATOR(pg_catalog.=) %s::regtype")
else:
self._query_pg_type = (
"SELECT oid, typname, typname::regtype,"
" typtype, typcategory, typdelim, typrelid"
" FROM pg_catalog.pg_type"
" WHERE oid OPERATOR(pg_catalog.=) %s::regtype")
def add(self, oid, pgtype, regtype,
typtype, category, delim, relid):
"""Create a PostgreSQL type name with additional info."""
if oid in self:
return self[oid]
simple = 'record' if relid else _simpletypes[pgtype]
typ = DbType(regtype if self._regtypes else simple)
typ.oid = oid
typ.simple = simple
typ.pgtype = pgtype
typ.regtype = regtype
typ.typtype = typtype
typ.category = category
typ.delim = delim
typ.relid = relid
typ._get_attnames = self.get_attnames
return typ
def __missing__(self, key):
"""Get the type info from the database if it is not cached."""
try:
q = self._query_pg_type % (_quote_if_unqualified('$1', key),)
res = self._db.query(q, (key,)).getresult()
except ProgrammingError:
res = None
if not res:
raise KeyError('Type %s could not be found' % key)
res = res[0]
typ = self.add(*res)
self[typ.oid] = self[typ.pgtype] = typ
return typ
def get(self, key, default=None):
"""Get the type even if it is not cached."""
try:
return self[key]
except KeyError:
return default
def get_attnames(self, typ):
"""Get names and types of the fields of a composite type."""
if not isinstance(typ, DbType):
typ = self.get(typ)
if not typ:
return None
if not typ.relid:
return None
return self._db.get_attnames(typ.relid, with_oid=False)
def get_typecast(self, typ):
"""Get the typecast function for the given database type."""
return self._typecasts.get(typ)
def set_typecast(self, typ, cast):
"""Set a typecast function for the specified database type(s)."""
self._typecasts.set(typ, cast)
def reset_typecast(self, typ=None):
"""Reset the typecast function for the specified database type(s)."""
self._typecasts.reset(typ)
def typecast(self, value, typ):
"""Cast the given value according to the given database type."""
if value is None:
# for NULL values, no typecast is necessary
return None
if not isinstance(typ, DbType):
typ = self.get(typ)
if typ:
typ = typ.pgtype
cast = self.get_typecast(typ) if typ else None
if not cast or cast is str:
# no typecast is necessary
return value
return cast(value)
_re_fieldname = regex('^[A-Za-z][_a-zA-Z0-9]*$')
# The result rows for database operations are returned as named tuples
# by default. Since creating namedtuple classes is a somewhat expensive
# operation, we cache up to 1024 of these classes by default.
@lru_cache(maxsize=1024)
def _row_factory(names):
"""Get a namedtuple factory for row results with the given names."""
try:
try:
return namedtuple('Row', names, rename=True)._make
except TypeError: # Python 2.6 and 3.0 do not support rename
names = [v if _re_fieldname.match(v) and not iskeyword(v)
else 'column_%d' % (n,)
for n, v in enumerate(names)]
return namedtuple('Row', names)._make
except ValueError: # there is still a problem with the field names
names = ['column_%d' % (n,) for n in range(len(names))]
return namedtuple('Row', names)._make
def set_row_factory_size(maxsize):
"""Change the size of the namedtuple factory cache.
If maxsize is set to None, the cache can grow without bound.
"""
global _row_factory
_row_factory = lru_cache(maxsize)(_row_factory.__wrapped__)
# Helper functions used by the query object
def _dictiter(q):
"""Get query result as an iterator of dictionaries."""
fields = q.listfields()
for r in q:
yield dict(zip(fields, r))
def _namediter(q):
"""Get query result as an iterator of named tuples."""
row = _row_factory(q.listfields())
for r in q:
yield row(r)
def _namednext(q):
"""Get next row from query result as a named tuple."""
return _row_factory(q.listfields())(next(q))
def _scalariter(q):
"""Get query result as an iterator of scalar values."""
for r in q:
yield r[0]
class _MemoryQuery:
"""Class that embodies a given query result."""
def __init__(self, result, fields):
"""Create query from given result rows and field names."""
self.result = result
self.fields = tuple(fields)
def listfields(self):
"""Return the stored field names of this query."""
return self.fields
def getresult(self):
"""Return the stored result of this query."""
return self.result
def __iter__(self):
return iter(self.result)
def _db_error(msg, cls=DatabaseError):
"""Return DatabaseError with empty sqlstate attribute."""
error = cls(msg)
error.sqlstate = None
return error
def _int_error(msg):
"""Return InternalError."""
return _db_error(msg, InternalError)
def _prg_error(msg):
"""Return ProgrammingError."""
return _db_error(msg, ProgrammingError)
# Initialize the C module
set_decimal(Decimal)
set_jsondecode(jsondecode)
set_query_helpers(_dictiter, _namediter, _namednext, _scalariter)
# The notification handler
class NotificationHandler(object):
"""A PostgreSQL client-side asynchronous notification handler."""
def __init__(self, db, event, callback=None,
arg_dict=None, timeout=None, stop_event=None):
"""Initialize the notification handler.
You must pass a PyGreSQL database connection, the name of an
event (notification channel) to listen for and a callback function.
You can also specify a dictionary arg_dict that will be passed as
the single argument to the callback function, and a timeout value
in seconds (a floating point number denotes fractions of seconds).
If it is absent or None, the callers will never time out. If the
timeout is reached, the callback function will be called with a
single argument that is None. If you set the timeout to zero,
the handler will poll notifications synchronously and return.
You can specify the name of the event that will be used to signal
the handler to stop listening as stop_event. By default, it will
be the event name prefixed with 'stop_'.
"""
self.db = db
self.event = event
self.stop_event = stop_event or 'stop_%s' % event
self.listening = False
self.callback = callback
if arg_dict is None:
arg_dict = {}
self.arg_dict = arg_dict
self.timeout = timeout
def __del__(self):
self.unlisten()
def close(self):
"""Stop listening and close the connection."""
if self.db:
self.unlisten()
self.db.close()
self.db = None
def listen(self):
"""Start listening for the event and the stop event."""
if not self.listening:
self.db.query('listen "%s"' % self.event)
self.db.query('listen "%s"' % self.stop_event)
self.listening = True
def unlisten(self):
"""Stop listening for the event and the stop event."""
if self.listening:
self.db.query('unlisten "%s"' % self.event)
self.db.query('unlisten "%s"' % self.stop_event)
self.listening = False
def notify(self, db=None, stop=False, payload=None):
"""Generate a notification.
Optionally, you can pass a payload with the notification.
If you set the stop flag, a stop notification will be sent that
will cause the handler to stop listening.
Note: If the notification handler is running in another thread, you
must pass a different database connection since PyGreSQL database
connections are not thread-safe.
"""
if self.listening:
if not db:
db = self.db
q = 'notify "%s"' % (self.stop_event if stop else self.event)
if payload:
q += ", '%s'" % payload
return db.query(q)
def __call__(self):
"""Invoke the notification handler.
The handler is a loop that listens for notifications on the event
and stop event channels. When either of these notifications are
received, its associated 'pid', 'event' and 'extra' (the payload
passed with the notification) are inserted into its arg_dict
dictionary and the callback is invoked with this dictionary as
a single argument. When the handler receives a stop event, it
stops listening to both events and return.
In the special case that the timeout of the handler has been set
to zero, the handler will poll all events synchronously and return.
If will keep listening until it receives a stop event.
Note: If you run this loop in another thread, don't use the same
database connection for database operations in the main thread.
"""
self.listen()
poll = self.timeout == 0
if not poll:
rlist = [self.db.fileno()]
while self.listening:
if poll or select.select(rlist, [], [], self.timeout)[0]:
while self.listening:
notice = self.db.getnotify()
if not notice: # no more messages
break
event, pid, extra = notice
if event not in (self.event, self.stop_event):
self.unlisten()
raise _db_error(
'Listening for "%s" and "%s", but notified of "%s"'
% (self.event, self.stop_event, event))
if event == self.stop_event:
self.unlisten()
self.arg_dict.update(pid=pid, event=event, extra=extra)
self.callback(self.arg_dict)
if poll:
break
else: # we timed out
self.unlisten()
self.callback(None)
def pgnotify(*args, **kw):
"""Same as NotificationHandler, under the traditional name."""
warnings.warn("pgnotify is deprecated, use NotificationHandler instead",
DeprecationWarning, stacklevel=2)
return NotificationHandler(*args, **kw)
# The actual PostgreSQL database connection interface:
class DB:
"""Wrapper class for the _pg connection type."""
db = None # invalid fallback for underlying connection
def __init__(self, *args, **kw):
"""Create a new connection
You can pass either the connection parameters or an existing
_pg or pgdb connection. This allows you to use the methods
of the classic pg interface with a DB-API 2 pgdb connection.
"""
if not args and len(kw) == 1:
db = kw.get('db')
elif not kw and len(args) == 1:
db = args[0]
else:
db = None
if db:
if isinstance(db, DB):
db = db.db
else:
try:
db = db._cnx
except AttributeError:
pass
if not db or not hasattr(db, 'db') or not hasattr(db, 'query'):
db = connect(*args, **kw)
self._db_args = args, kw
self._closeable = True
else:
self._db_args = db
self._closeable = False
self.db = db
self.dbname = db.db
self._regtypes = False
self._attnames = {}
self._pkeys = {}
self._privileges = {}
self.adapter = Adapter(self)
self.dbtypes = DbTypes(self)
if db.server_version < 80400:
# support older remote data bases (not officially supported)
self._query_attnames = (
"SELECT a.attname, t.oid, t.typname, t.typname::text::regtype,"
" t.typtype, null as typcategory, t.typdelim, t.typrelid"
" FROM pg_catalog.pg_attribute a"
" JOIN pg_catalog.pg_type t"
" ON t.oid OPERATOR(pg_catalog.=) a.atttypid"
" WHERE a.attrelid OPERATOR(pg_catalog.=) %s::regclass AND %s"
" AND NOT a.attisdropped ORDER BY a.attnum")
else:
self._query_attnames = (
"SELECT a.attname, t.oid, t.typname, t.typname::regtype,"
" t.typtype, t.typcategory, t.typdelim, t.typrelid"
" FROM pg_catalog.pg_attribute a"
" JOIN pg_catalog.pg_type t"
" ON t.oid OPERATOR(pg_catalog.=) a.atttypid"
" WHERE a.attrelid OPERATOR(pg_catalog.=) %s::regclass AND %s"
" AND NOT a.attisdropped ORDER BY a.attnum")
db.set_cast_hook(self.dbtypes.typecast)
self.debug = None # For debugging scripts, this can be set
# * to a string format specification (e.g. in CGI set to "%s<BR>"),
# * to a file object to write debug statements or
# * to a callable object which takes a string argument
# * to any other true value to just print debug statements
def __getattr__(self, name):
# All undefined members are same as in underlying connection:
if self.db:
return getattr(self.db, name)
else:
raise _int_error('Connection is not valid')
def __dir__(self):
# Custom dir function including the attributes of the connection:
attrs = set(self.__class__.__dict__)
attrs.update(self.__dict__)
attrs.update(dir(self.db))
return sorted(attrs)
# Context manager methods
def __enter__(self):
"""Enter the runtime context. This will start a transaction."""
self.begin()
return self
def __exit__(self, et, ev, tb):
"""Exit the runtime context. This will end the transaction."""
if et is None and ev is None and tb is None:
self.commit()
else:
self.rollback()
def __del__(self):
try:
db = self.db
except AttributeError:
db = None
if db:
try:
db.set_cast_hook(None)
except TypeError:
pass # probably already closed
if self._closeable:
try:
db.close()
except InternalError:
pass # probably already closed
# Auxiliary methods
def _do_debug(self, *args):
"""Print a debug message"""
if self.debug:
s = '\n'.join(str(arg) for arg in args)
if isinstance(self.debug, basestring):
print(self.debug % s)
elif hasattr(self.debug, 'write'):
self.debug.write(s + '\n')
elif callable(self.debug):
self.debug(s)
else:
print(s)
def _escape_qualified_name(self, s):
"""Escape a qualified name.
Escapes the name for use as an SQL identifier, unless the
name contains a dot, in which case the name is ambiguous
(could be a qualified name or just a name with a dot in it)
and must be quoted manually by the caller.
"""
if '.' not in s:
s = self.escape_identifier(s)
return s
@staticmethod
def _make_bool(d):
"""Get boolean value corresponding to d."""
return bool(d) if get_bool() else ('t' if d else 'f')
def _list_params(self, params):
"""Create a human readable parameter list."""
return ', '.join('$%d=%r' % (n, v) for n, v in enumerate(params, 1))
# Public methods
# escape_string and escape_bytea exist as methods,
# so we define unescape_bytea as a method as well
unescape_bytea = staticmethod(unescape_bytea)
def decode_json(self, s):
"""Decode a JSON string coming from the database."""
return (get_jsondecode() or jsondecode)(s)
def encode_json(self, d):
"""Encode a JSON string for use within SQL."""
return jsonencode(d)
def close(self):
"""Close the database connection."""
# Wraps shared library function so we can track state.
db = self.db
if db:
try:
db.set_cast_hook(None)
except TypeError:
pass # probably already closed
if self._closeable:
db.close()
self.db = None
else:
raise _int_error('Connection already closed')
def reset(self):
"""Reset connection with current parameters.
All derived queries and large objects derived from this connection
will not be usable after this call.
"""
if self.db:
self.db.reset()
else:
raise _int_error('Connection already closed')
def reopen(self):
"""Reopen connection to the database.
Used in case we need another connection to the same database.
Note that we can still reopen a database that we have closed.
"""
# There is no such shared library function.
if self._closeable:
db = connect(*self._db_args[0], **self._db_args[1])
if self.db:
self.db.set_cast_hook(None)
self.db.close()
db.set_cast_hook(self.dbtypes.typecast)
self.db = db
else:
self.db = self._db_args
def begin(self, mode=None):
"""Begin a transaction."""
qstr = 'BEGIN'
if mode:
qstr += ' ' + mode
return self.query(qstr)
start = begin
def commit(self):
"""Commit the current transaction."""
return self.query('COMMIT')
end = commit
def rollback(self, name=None):
"""Roll back the current transaction."""
qstr = 'ROLLBACK'
if name:
qstr += ' TO ' + name
return self.query(qstr)
abort = rollback
def savepoint(self, name):
"""Define a new savepoint within the current transaction."""
return self.query('SAVEPOINT ' + name)
def release(self, name):
"""Destroy a previously defined savepoint."""
return self.query('RELEASE ' + name)
def get_parameter(self, parameter):
"""Get the value of a run-time parameter.
If the parameter is a string, the return value will also be a string
that is the current setting of the run-time parameter with that name.
You can get several parameters at once by passing a list, set or dict.
When passing a list of parameter names, the return value will be a
corresponding list of parameter settings. When passing a set of
parameter names, a new dict will be returned, mapping these parameter
names to their settings. Finally, if you pass a dict as parameter,
its values will be set to the current parameter settings corresponding
to its keys.
By passing the special name 'all' as the parameter, you can get a dict
of all existing configuration parameters.
"""
if isinstance(parameter, basestring):
parameter = [parameter]
values = None
elif isinstance(parameter, (list, tuple)):
values = []
elif isinstance(parameter, (set, frozenset)):
values = {}
elif isinstance(parameter, dict):
values = parameter
else:
raise TypeError(
'The parameter must be a string, list, set or dict')
if not parameter:
raise TypeError('No parameter has been specified')
params = {} if isinstance(values, dict) else []
for key in parameter:
param = key.strip().lower() if isinstance(
key, basestring) else None
if not param:
raise TypeError('Invalid parameter')
if param == 'all':
q = 'SHOW ALL'
values = self.db.query(q).getresult()
values = dict(value[:2] for value in values)
break
if isinstance(values, dict):
params[param] = key
else:
params.append(param)
else:
for param in params:
q = 'SHOW %s' % (param,)
value = self.db.query(q).getresult()[0][0]
if values is None:
values = value
elif isinstance(values, list):
values.append(value)
else:
values[params[param]] = value
return values
def set_parameter(self, parameter, value=None, local=False):
"""Set the value of a run-time parameter.
If the parameter and the value are strings, the run-time parameter
will be set to that value. If no value or None is passed as a value,
then the run-time parameter will be restored to its default value.
You can set several parameters at once by passing a list of parameter
names, together with a single value that all parameters should be
set to or with a corresponding list of values. You can also pass
the parameters as a set if you only provide a single value.
Finally, you can pass a dict with parameter names as keys. In this
case, you should not pass a value, since the values for the parameters
will be taken from the dict.
By passing the special name 'all' as the parameter, you can reset
all existing settable run-time parameters to their default values.
If you set local to True, then the command takes effect for only the
current transaction. After commit() or rollback(), the session-level
setting takes effect again. Setting local to True will appear to
have no effect if it is executed outside a transaction, since the
transaction will end immediately.
"""
if isinstance(parameter, basestring):
parameter = {parameter: value}
elif isinstance(parameter, (list, tuple)):
if isinstance(value, (list, tuple)):
parameter = dict(zip(parameter, value))
else:
parameter = dict.fromkeys(parameter, value)
elif isinstance(parameter, (set, frozenset)):
if isinstance(value, (list, tuple, set, frozenset)):
value = set(value)
if len(value) == 1:
value = value.pop()
if not(value is None or isinstance(value, basestring)):
raise ValueError('A single value must be specified'
' when parameter is a set')
parameter = dict.fromkeys(parameter, value)
elif isinstance(parameter, dict):
if value is not None:
raise ValueError('A value must not be specified'
' when parameter is a dictionary')
else:
raise TypeError(
'The parameter must be a string, list, set or dict')
if not parameter:
raise TypeError('No parameter has been specified')
params = {}
for key, value in parameter.items():
param = key.strip().lower() if isinstance(
key, basestring) else None
if not param:
raise TypeError('Invalid parameter')
if param == 'all':
if value is not None:
raise ValueError('A value must ot be specified'
" when parameter is 'all'")
params = {'all': None}
break
params[param] = value
local = ' LOCAL' if local else ''
for param, value in params.items():
if value is None:
q = 'RESET%s %s' % (local, param)
else:
q = 'SET%s %s TO %s' % (local, param, value)
self._do_debug(q)
self.db.query(q)
def query(self, command, *args):
"""Execute a SQL command string.
This method simply sends a SQL query to the database. If the query is
an insert statement that inserted exactly one row into a table that
has OIDs, the return value is the OID of the newly inserted row.
If the query is an update or delete statement, or an insert statement
that did not insert exactly one row in a table with OIDs, then the
number of rows affected is returned as a string. If it is a statement
that returns rows as a result (usually a select statement, but maybe
also an "insert/update ... returning" statement), this method returns
a Query object that can be accessed via getresult() or dictresult()
or simply printed. Otherwise, it returns `None`.
The query can contain numbered parameters of the form $1 in place
of any data constant. Arguments given after the query string will
be substituted for the corresponding numbered parameter. Parameter
values can also be given as a single list or tuple argument.
"""
# Wraps shared library function for debugging.
if not self.db:
raise _int_error('Connection is not valid')
if args:
self._do_debug(command, args)
return self.db.query(command, args)
self._do_debug(command)
return self.db.query(command)
def query_formatted(self, command,
parameters=None, types=None, inline=False):
"""Execute a formatted SQL command string.
Similar to query, but using Python format placeholders of the form
%s or %(names)s instead of PostgreSQL placeholders of the form $1.
The parameters must be passed as a tuple, list or dict. You can
also pass a corresponding tuple, list or dict of database types in
order to format the parameters properly in case there is ambiguity.
If you set inline to True, the parameters will be sent to the database
embedded in the SQL command, otherwise they will be sent separately.
"""
return self.query(*self.adapter.format_query(
command, parameters, types, inline))
def query_prepared(self, name, *args):
"""Execute a prepared SQL statement.
This works like the query() method, except that instead of passing
the SQL command, you pass the name of a prepared statement. If you
pass an empty name, the unnamed statement will be executed.
"""
if not self.db:
raise _int_error('Connection is not valid')
if name is None:
name = ''
if args:
self._do_debug('EXECUTE', name, args)
return self.db.query_prepared(name, args)
self._do_debug('EXECUTE', name)
return self.db.query_prepared(name)
def prepare(self, name, command):
"""Create a prepared SQL statement.
This creates a prepared statement for the given command with the
given name for later execution with the query_prepared() method.
The name can be empty to create an unnamed statement, in which case
any pre-existing unnamed statement is automatically replaced;
otherwise it is an error if the statement name is already
defined in the current database session. We recommend always using
named queries, since unnamed queries have a limited lifetime and
can be automatically replaced or destroyed by various operations.
"""
if not self.db:
raise _int_error('Connection is not valid')
if name is None:
name = ''
self._do_debug('prepare', name, command)
return self.db.prepare(name, command)
def describe_prepared(self, name=None):
"""Describe a prepared SQL statement.
This method returns a Query object describing the result columns of
the prepared statement with the given name. If you omit the name,
the unnamed statement will be described if you created one before.
"""
if name is None:
name = ''
return self.db.describe_prepared(name)
def delete_prepared(self, name=None):
"""Delete a prepared SQL statement
This deallocates a previously prepared SQL statement with the given
name, or deallocates all prepared statements if you do not specify a
name. Note that prepared statements are also deallocated automatically
when the current session ends.
"""
q = "DEALLOCATE %s" % (name or 'ALL',)
self._do_debug(q)
return self.db.query(q)
def pkey(self, table, composite=False, flush=False):
"""Get or set the primary key of a table.
Single primary keys are returned as strings unless you
set the composite flag. Composite primary keys are always
represented as tuples. Note that this raises a KeyError
if the table does not have a primary key.
If flush is set then the internal cache for primary keys will
be flushed. This may be necessary after the database schema or
the search path has been changed.
"""
pkeys = self._pkeys
if flush:
pkeys.clear()
self._do_debug('The pkey cache has been flushed')
try: # cache lookup
pkey = pkeys[table]
except KeyError: # cache miss, check the database
q = ("SELECT a.attname, a.attnum, i.indkey"
" FROM pg_catalog.pg_index i"
" JOIN pg_catalog.pg_attribute a"
" ON a.attrelid OPERATOR(pg_catalog.=) i.indrelid"
" AND a.attnum OPERATOR(pg_catalog.=) ANY(i.indkey)"
" AND NOT a.attisdropped"
" WHERE i.indrelid OPERATOR(pg_catalog.=) %s::regclass"
" AND i.indisprimary ORDER BY a.attnum") % (
_quote_if_unqualified('$1', table),)
pkey = self.db.query(q, (table,)).getresult()
if not pkey:
raise KeyError('Table %s has no primary key' % table)
# we want to use the order defined in the primary key index here,
# not the order as defined by the columns in the table
if len(pkey) > 1:
indkey = pkey[0][2]
pkey = sorted(pkey, key=lambda row: indkey.index(row[1]))
pkey = tuple(row[0] for row in pkey)
else:
pkey = pkey[0][0]
pkeys[table] = pkey # cache it
if composite and not isinstance(pkey, tuple):
pkey = (pkey,)
return pkey
def get_databases(self):
"""Get list of databases in the system."""
return [s[0] for s in
self.db.query(
'SELECT datname FROM pg_catalog.pg_database').getresult()]
def get_relations(self, kinds=None, system=False):
"""Get list of relations in connected database of specified kinds.
If kinds is None or empty, all kinds of relations are returned.
Otherwise kinds can be a string or sequence of type letters
specifying which kind of relations you want to list.
Set the system flag if you want to get the system relations as well.
"""
where = []
if kinds:
where.append("r.relkind IN (%s)" %
','.join("'%s'" % k for k in kinds))
if not system:
where.append("s.nspname NOT SIMILAR"
" TO 'pg/_%|information/_schema' ESCAPE '/'")
where = " WHERE %s" % ' AND '.join(where) if where else ''
q = ("SELECT pg_catalog.quote_ident(s.nspname) OPERATOR(pg_catalog.||)"
" '.' OPERATOR(pg_catalog.||) pg_catalog.quote_ident(r.relname)"
" FROM pg_catalog.pg_class r"
" JOIN pg_catalog.pg_namespace s"
" ON s.oid OPERATOR(pg_catalog.=) r.relnamespace%s"
" ORDER BY s.nspname, r.relname") % where
return [r[0] for r in self.db.query(q).getresult()]
def get_tables(self, system=False):
"""Return list of tables in connected database.
Set the system flag if you want to get the system tables as well.
"""
return self.get_relations('r', system)
def get_attnames(self, table, with_oid=True, flush=False):
"""Given the name of a table, dig out the set of attribute names.
Returns a read-only dictionary of attribute names (the names are
the keys, the values are the names of the attributes' types)
with the column names in the proper order if you iterate over it.
If flush is set, then the internal cache for attribute names will
be flushed. This may be necessary after the database schema or
the search path has been changed.
By default, only a limited number of simple types will be returned.
You can get the registered types after calling use_regtypes(True).
"""
attnames = self._attnames
if flush:
attnames.clear()
self._do_debug('The attnames cache has been flushed')
try: # cache lookup
names = attnames[table]
except KeyError: # cache miss, check the database
q = "a.attnum OPERATOR(pg_catalog.>) 0"
if with_oid:
q = "(%s OR a.attname OPERATOR(pg_catalog.=) 'oid')" % q
q = self._query_attnames % (_quote_if_unqualified('$1', table), q)
names = self.db.query(q, (table,)).getresult()
types = self.dbtypes
names = ((name[0], types.add(*name[1:])) for name in names)
names = AttrDict(names)
attnames[table] = names # cache it
return names
def use_regtypes(self, regtypes=None):
"""Use registered type names instead of simplified type names."""
if regtypes is None:
return self.dbtypes._regtypes
else:
regtypes = bool(regtypes)
if regtypes != self.dbtypes._regtypes:
self.dbtypes._regtypes = regtypes
self._attnames.clear()
self.dbtypes.clear()
return regtypes
def has_table_privilege(self, table, privilege='select', flush=False):
"""Check whether current user has specified table privilege.
If flush is set, then the internal cache for table privileges will
be flushed. This may be necessary after privileges have been changed.
"""
privileges = self._privileges
if flush:
privileges.clear()
self._do_debug('The privileges cache has been flushed')
privilege = privilege.lower()
try: # ask cache
ret = privileges[table, privilege]
except KeyError: # cache miss, ask the database
q = "SELECT pg_catalog.has_table_privilege(%s, $2)" % (
_quote_if_unqualified('$1', table),)
q = self.db.query(q, (table, privilege))
ret = q.getresult()[0][0] == self._make_bool(True)
privileges[table, privilege] = ret # cache it
return ret
def get(self, table, row, keyname=None):
"""Get a row from a database table or view.
This method is the basic mechanism to get a single row. It assumes
that the keyname specifies a unique row. It must be the name of a
single column or a tuple of column names. If the keyname is not
specified, then the primary key for the table is used.
If row is a dictionary, then the value for the key is taken from it.
Otherwise, the row must be a single value or a tuple of values
corresponding to the passed keyname or primary key. The fetched row
from the table will be returned as a new dictionary or used to replace
the existing values when row was passed as a dictionary.
The OID is also put into the dictionary if the table has one, but
in order to allow the caller to work with multiple tables, it is
munged as "oid(table)" using the actual name of the table.
"""
if table.endswith('*'): # hint for descendant tables can be ignored
table = table[:-1].rstrip()
attnames = self.get_attnames(table)
qoid = _oid_key(table) if 'oid' in attnames else None
if keyname and isinstance(keyname, basestring):
keyname = (keyname,)
if qoid and isinstance(row, dict) and qoid in row and 'oid' not in row:
row['oid'] = row[qoid]
if not keyname:
try: # if keyname is not specified, try using the primary key
keyname = self.pkey(table, True)
except KeyError: # the table has no primary key
# try using the oid instead
if qoid and isinstance(row, dict) and 'oid' in row:
keyname = ('oid',)
else:
raise _prg_error('Table %s has no primary key' % table)
else: # the table has a primary key
# check whether all key columns have values
if isinstance(row, dict) and not set(keyname).issubset(row):
# try using the oid instead
if qoid and 'oid' in row:
keyname = ('oid',)
else:
raise KeyError(
'Missing value in row for specified keyname')
if not isinstance(row, dict):
if not isinstance(row, (tuple, list)):
row = [row]
if len(keyname) != len(row):
raise KeyError(
'Differing number of items in keyname and row')
row = dict(zip(keyname, row))
params = self.adapter.parameter_list()
adapt = params.add
col = self.escape_identifier
what = 'oid, *' if qoid else '*'
where = ' AND '.join('%s OPERATOR(pg_catalog.=) %s' % (
col(k), adapt(row[k], attnames[k])) for k in keyname)
if 'oid' in row:
if qoid:
row[qoid] = row['oid']
del row['oid']
q = 'SELECT %s FROM %s WHERE %s LIMIT 1' % (
what, self._escape_qualified_name(table), where)
self._do_debug(q, params)
q = self.db.query(q, params)
res = q.dictresult()
if not res:
# make where clause in error message better readable
where = where.replace('OPERATOR(pg_catalog.=)', '=')
raise _db_error('No such record in %s\nwhere %s\nwith %s' % (
table, where, self._list_params(params)))
for n, value in res[0].items():
if qoid and n == 'oid':
n = qoid
row[n] = value
return row
def insert(self, table, row=None, **kw):
"""Insert a row into a database table.
This method inserts a row into a table. The name of the table must
be passed as the first parameter. The other parameters are used for
providing the data of the row that shall be inserted into the table.
If a dictionary is supplied as the second parameter, it starts with
that. Otherwise it uses a blank dictionary. Either way the dictionary
is updated from the keywords.
The dictionary is then reloaded with the values actually inserted in
order to pick up values modified by rules, triggers, etc.
"""
if table.endswith('*'): # hint for descendant tables can be ignored
table = table[:-1].rstrip()
if row is None:
row = {}
row.update(kw)
if 'oid' in row:
del row['oid'] # do not insert oid
attnames = self.get_attnames(table)
qoid = _oid_key(table) if 'oid' in attnames else None
params = self.adapter.parameter_list()
adapt = params.add
col = self.escape_identifier
names, values = [], []
for n in attnames:
if n in row:
names.append(col(n))
values.append(adapt(row[n], attnames[n]))
if not names:
raise _prg_error('No column found that can be inserted')
names, values = ', '.join(names), ', '.join(values)
ret = 'oid, *' if qoid else '*'
q = 'INSERT INTO %s (%s) VALUES (%s) RETURNING %s' % (
self._escape_qualified_name(table), names, values, ret)
self._do_debug(q, params)
q = self.db.query(q, params)
res = q.dictresult()
if res: # this should always be true
for n, value in res[0].items():
if qoid and n == 'oid':
n = qoid
row[n] = value
return row
def update(self, table, row=None, **kw):
"""Update an existing row in a database table.
Similar to insert, but updates an existing row. The update is based
on the primary key of the table or the OID value as munged by get()
or passed as keyword. The OID will take precedence if provided, so
that it is possible to update the primary key itself.
The dictionary is then modified to reflect any changes caused by the
update due to triggers, rules, default values, etc.
"""
if table.endswith('*'):
table = table[:-1].rstrip() # need parent table name
attnames = self.get_attnames(table)
qoid = _oid_key(table) if 'oid' in attnames else None
if row is None:
row = {}
elif 'oid' in row:
del row['oid'] # only accept oid key from named args for safety
row.update(kw)
if qoid and qoid in row and 'oid' not in row:
row['oid'] = row[qoid]
if qoid and 'oid' in row: # try using the oid
keyname = ('oid',)
else: # try using the primary key
try:
keyname = self.pkey(table, True)
except KeyError: # the table has no primary key
raise _prg_error('Table %s has no primary key' % table)
# check whether all key columns have values
if not set(keyname).issubset(row):
raise KeyError('Missing value for primary key in row')
params = self.adapter.parameter_list()
adapt = params.add
col = self.escape_identifier
where = ' AND '.join('%s OPERATOR(pg_catalog.=) %s' % (
col(k), adapt(row[k], attnames[k])) for k in keyname)
if 'oid' in row:
if qoid:
row[qoid] = row['oid']
del row['oid']
values = []
keyname = set(keyname)
for n in attnames:
if n in row and n not in keyname:
values.append('%s = %s' % (col(n), adapt(row[n], attnames[n])))
if not values:
return row
values = ', '.join(values)
ret = 'oid, *' if qoid else '*'
q = 'UPDATE %s SET %s WHERE %s RETURNING %s' % (
self._escape_qualified_name(table), values, where, ret)
self._do_debug(q, params)
q = self.db.query(q, params)
res = q.dictresult()
if res: # may be empty when row does not exist
for n, value in res[0].items():
if qoid and n == 'oid':
n = qoid
row[n] = value
return row
def upsert(self, table, row=None, **kw):
"""Insert a row into a database table with conflict resolution
This method inserts a row into a table, but instead of raising a
ProgrammingError exception in case a row with the same primary key
already exists, an update will be executed instead. This will be
performed as a single atomic operation on the database, so race
conditions can be avoided.
Like the insert method, the first parameter is the name of the
table and the second parameter can be used to pass the values to
be inserted as a dictionary.
Unlike the insert und update statement, keyword parameters are not
used to modify the dictionary, but to specify which columns shall
be updated in case of a conflict, and in which way:
A value of False or None means the column shall not be updated,
a value of True means the column shall be updated with the value
that has been proposed for insertion, i.e. has been passed as value
in the dictionary. Columns that are not specified by keywords but
appear as keys in the dictionary are also updated like in the case
keywords had been passed with the value True.
So if in the case of a conflict you want to update every column that
has been passed in the dictionary row, you would call upsert(table, row).
If you don't want to do anything in case of a conflict, i.e. leave
the existing row as it is, call upsert(table, row, **dict.fromkeys(row)).
If you need more fine-grained control of what gets updated, you can
also pass strings in the keyword parameters. These strings will
be used as SQL expressions for the update columns. In these
expressions you can refer to the value that already exists in
the table by prefixing the column name with "included.", and to
the value that has been proposed for insertion by prefixing the
column name with the "excluded."
The dictionary is modified in any case to reflect the values in
the database after the operation has completed.
Note: The method uses the PostgreSQL "upsert" feature which is
only available since PostgreSQL 9.5.
"""
if table.endswith('*'): # hint for descendant tables can be ignored
table = table[:-1].rstrip()
if row is None:
row = {}
if 'oid' in row:
del row['oid'] # do not insert oid
if 'oid' in kw:
del kw['oid'] # do not update oid
attnames = self.get_attnames(table)
qoid = _oid_key(table) if 'oid' in attnames else None
params = self.adapter.parameter_list()
adapt = params.add
col = self.escape_identifier
names, values, updates = [], [], []
for n in attnames:
if n in row:
names.append(col(n))
values.append(adapt(row[n], attnames[n]))
names, values = ', '.join(names), ', '.join(values)
try:
keyname = self.pkey(table, True)
except KeyError:
raise _prg_error('Table %s has no primary key' % table)
target = ', '.join(col(k) for k in keyname)
update = []
keyname = set(keyname)
keyname.add('oid')
for n in attnames:
if n not in keyname:
value = kw.get(n, True)
if value:
if not isinstance(value, basestring):
value = 'excluded.%s' % col(n)
update.append('%s = %s' % (col(n), value))
if not values:
return row
do = 'update set %s' % ', '.join(update) if update else 'nothing'
ret = 'oid, *' if qoid else '*'
q = ('INSERT INTO %s AS included (%s) VALUES (%s)'
' ON CONFLICT (%s) DO %s RETURNING %s') % (
self._escape_qualified_name(table), names, values,
target, do, ret)
self._do_debug(q, params)
try:
q = self.db.query(q, params)
except ProgrammingError:
if self.server_version < 90500:
raise _prg_error(
'Upsert operation is not supported by PostgreSQL version')
raise # re-raise original error
res = q.dictresult()
if res: # may be empty with "do nothing"
for n, value in res[0].items():
if qoid and n == 'oid':
n = qoid
row[n] = value
else:
self.get(table, row)
return row
def clear(self, table, row=None):
"""Clear all the attributes to values determined by the types.
Numeric types are set to 0, Booleans are set to false, and everything
else is set to the empty string. If the row argument is present,
it is used as the row dictionary and any entries matching attribute
names are cleared with everything else left unchanged.
"""
# At some point we will need a way to get defaults from a table.
if row is None:
row = {} # empty if argument is not present
attnames = self.get_attnames(table)
for n, t in attnames.items():
if n == 'oid':
continue
t = t.simple
if t in DbTypes._num_types:
row[n] = 0
elif t == 'bool':
row[n] = self._make_bool(False)
else:
row[n] = ''
return row
def delete(self, table, row=None, **kw):
"""Delete an existing row in a database table.
This method deletes the row from a table. It deletes based on the
primary key of the table or the OID value as munged by get() or
passed as keyword. The OID will take precedence if provided.
The return value is the number of deleted rows (i.e. 0 if the row
did not exist and 1 if the row was deleted).
Note that if the row cannot be deleted because e.g. it is still
referenced by another table, this method raises a ProgrammingError.
"""
if table.endswith('*'): # hint for descendant tables can be ignored
table = table[:-1].rstrip()
attnames = self.get_attnames(table)
qoid = _oid_key(table) if 'oid' in attnames else None
if row is None:
row = {}
elif 'oid' in row:
del row['oid'] # only accept oid key from named args for safety
row.update(kw)
if qoid and qoid in row and 'oid' not in row:
row['oid'] = row[qoid]
if qoid and 'oid' in row: # try using the oid
keyname = ('oid',)
else: # try using the primary key
try:
keyname = self.pkey(table, True)
except KeyError: # the table has no primary key
raise _prg_error('Table %s has no primary key' % table)
# check whether all key columns have values
if not set(keyname).issubset(row):
raise KeyError('Missing value for primary key in row')
params = self.adapter.parameter_list()
adapt = params.add
col = self.escape_identifier
where = ' AND '.join('%s OPERATOR(pg_catalog.=) %s' % (
col(k), adapt(row[k], attnames[k])) for k in keyname)
if 'oid' in row:
if qoid:
row[qoid] = row['oid']
del row['oid']
q = 'DELETE FROM %s WHERE %s' % (
self._escape_qualified_name(table), where)
self._do_debug(q, params)
res = self.db.query(q, params)
return int(res)
def truncate(self, table, restart=False, cascade=False, only=False):
"""Empty a table or set of tables.
This method quickly removes all rows from the given table or set
of tables. It has the same effect as an unqualified DELETE on each
table, but since it does not actually scan the tables it is faster.
Furthermore, it reclaims disk space immediately, rather than requiring
a subsequent VACUUM operation. This is most useful on large tables.
If restart is set to True, sequences owned by columns of the truncated
table(s) are automatically restarted. If cascade is set to True, it
also truncates all tables that have foreign-key references to any of
the named tables. If the parameter only is not set to True, all the
descendant tables (if any) will also be truncated. Optionally, a '*'
can be specified after the table name to explicitly indicate that
descendant tables are included.
"""
if isinstance(table, basestring):
only = {table: only}
table = [table]
elif isinstance(table, (list, tuple)):
if isinstance(only, (list, tuple)):
only = dict(zip(table, only))
else:
only = dict.fromkeys(table, only)
elif isinstance(table, (set, frozenset)):
only = dict.fromkeys(table, only)
else:
raise TypeError('The table must be a string, list or set')
if not (restart is None or isinstance(restart, (bool, int))):
raise TypeError('Invalid type for the restart option')
if not (cascade is None or isinstance(cascade, (bool, int))):
raise TypeError('Invalid type for the cascade option')
tables = []
for t in table:
u = only.get(t)
if not (u is None or isinstance(u, (bool, int))):
raise TypeError('Invalid type for the only option')
if t.endswith('*'):
if u:
raise ValueError(
'Contradictory table name and only options')
t = t[:-1].rstrip()
t = self._escape_qualified_name(t)
if u:
t = 'ONLY %s' % t
tables.append(t)
q = ['TRUNCATE', ', '.join(tables)]
if restart:
q.append('RESTART IDENTITY')
if cascade:
q.append('CASCADE')
q = ' '.join(q)
self._do_debug(q)
return self.db.query(q)
def get_as_list(self, table, what=None, where=None,
order=None, limit=None, offset=None, scalar=False):
"""Get a table as a list.
This gets a convenient representation of the table as a list
of named tuples in Python. You only need to pass the name of
the table (or any other SQL expression returning rows). Note that
by default this will return the full content of the table which
can be huge and overflow your memory. However, you can control
the amount of data returned using the other optional parameters.
The parameter 'what' can restrict the query to only return a
subset of the table columns. It can be a string, list or a tuple.
The parameter 'where' can restrict the query to only return a
subset of the table rows. It can be a string, list or a tuple
of SQL expressions that all need to be fulfilled. The parameter
'order' specifies the ordering of the rows. It can also be a
other string, list or a tuple. If no ordering is specified,
the result will be ordered by the primary key(s) or all columns
if no primary key exists. You can set 'order' to False if you
don't care about the ordering. The parameters 'limit' and 'offset'
can be integers specifying the maximum number of rows returned
and a number of rows skipped over.
If you set the 'scalar' option to True, then instead of the
named tuples you will get the first items of these tuples.
This is useful if the result has only one column anyway.
"""
if not table:
raise TypeError('The table name is missing')
if what:
if isinstance(what, (list, tuple)):
what = ', '.join(map(str, what))
if order is None:
order = what
else:
what = '*'
q = ['SELECT', what, 'FROM', table]
if where:
if isinstance(where, (list, tuple)):
where = ' AND '.join(map(str, where))
q.extend(['WHERE', where])
if order is None:
try:
order = self.pkey(table, True)
except (KeyError, ProgrammingError):
try:
order = list(self.get_attnames(table))
except (KeyError, ProgrammingError):
pass
if order:
if isinstance(order, (list, tuple)):
order = ', '.join(map(str, order))
q.extend(['ORDER BY', order])
if limit:
q.append('LIMIT %d' % limit)
if offset:
q.append('OFFSET %d' % offset)
q = ' '.join(q)
self._do_debug(q)
q = self.db.query(q)
res = q.namedresult()
if res and scalar:
res = [row[0] for row in res]
return res
def get_as_dict(self, table, keyname=None, what=None, where=None,
order=None, limit=None, offset=None, scalar=False):
"""Get a table as a dictionary.
This method is similar to get_as_list(), but returns the table
as a Python dict instead of a Python list, which can be even
more convenient. The primary key column(s) of the table will
be used as the keys of the dictionary, while the other column(s)
will be the corresponding values. The keys will be named tuples
if the table has a composite primary key. The rows will be also
named tuples unless the 'scalar' option has been set to True.
With the optional parameter 'keyname' you can specify an alternative
set of columns to be used as the keys of the dictionary. It must
be set as a string, list or a tuple.
If the Python version supports it, the dictionary will be an
OrderedDict using the order specified with the 'order' parameter
or the key column(s) if not specified. You can set 'order' to False
if you don't care about the ordering. In this case the returned
dictionary will be an ordinary one.
"""
if not table:
raise TypeError('The table name is missing')
if not keyname:
try:
keyname = self.pkey(table, True)
except (KeyError, ProgrammingError):
raise _prg_error('Table %s has no primary key' % table)
if isinstance(keyname, basestring):
keyname = [keyname]
elif not isinstance(keyname, (list, tuple)):
raise KeyError('The keyname must be a string, list or tuple')
if what:
if isinstance(what, (list, tuple)):
what = ', '.join(map(str, what))
if order is None:
order = what
else:
what = '*'
q = ['SELECT', what, 'FROM', table]
if where:
if isinstance(where, (list, tuple)):
where = ' AND '.join(map(str, where))
q.extend(['WHERE', where])
if order is None:
order = keyname
if order:
if isinstance(order, (list, tuple)):
order = ', '.join(map(str, order))
q.extend(['ORDER BY', order])
if limit:
q.append('LIMIT %d' % limit)
if offset:
q.append('OFFSET %d' % offset)
q = ' '.join(q)
self._do_debug(q)
q = self.db.query(q)
res = q.getresult()
cls = OrderedDict if order else dict
if not res:
return cls()
keyset = set(keyname)
fields = q.listfields()
if not keyset.issubset(fields):
raise KeyError('Missing keyname in row')
keyind, rowind = [], []
for i, f in enumerate(fields):
(keyind if f in keyset else rowind).append(i)
keytuple = len(keyind) > 1
getkey = itemgetter(*keyind)
keys = map(getkey, res)
if scalar:
rowind = rowind[:1]
rowtuple = False
else:
rowtuple = len(rowind) > 1
if scalar or rowtuple:
getrow = itemgetter(*rowind)
else:
rowind = rowind[0]
getrow = lambda row: (row[rowind],)
rowtuple = True
rows = map(getrow, res)
if keytuple or rowtuple:
if keytuple:
keys = _namediter(_MemoryQuery(keys, keyname))
if rowtuple:
fields = [f for f in fields if f not in keyset]
rows = _namediter(_MemoryQuery(rows, fields))
return cls(zip(keys, rows))
def notification_handler(self,
event, callback, arg_dict=None, timeout=None, stop_event=None):
"""Get notification handler that will run the given callback."""
return NotificationHandler(self,
event, callback, arg_dict, timeout, stop_event)
# if run as script, print some information
if __name__ == '__main__':
print('PyGreSQL version' + version)
print('')
print(__doc__)