Hi.
I haven't had time to work up a unit test, and I haven't checked against
trunk, yet, but it's no longer possible to db.insert() into a temp table
in 4.2.1, and presumably beyond.
e.g., this fails:
db.query("create temp table x (y int)")
db.insert('x', {'y' : 23 })
with this stack trace:
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "pg.py", line 949, in insert
attnames = self.get_attnames(qcl)
File "pg.py", line 805, in get_attnames
raise _prg_error('Class %s does not exist' % qcl)
pg.ProgrammingError: Class pg_temp_2.x does not exist
I've attached a patch against 4.2.1 that addresses the issue. Basically,
it accepts namespaces that start with "pg_te" in get_relations() and
pkey().
--
Patrick TJ McPhee <[email protected]>
#! /usr/bin/python
#
# pg.py
#
# $Id: pg.py 775 2016-01-21 19:07:16Z cito $
#
"""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.
"""
# Copyright (c) 1997-2016 by D'Arcy J.M. Cain.
#
# Contributions made by Ch. Zwerschke and others.
#
# The notification handler is based on pgnotify which is
# Copyright (c) 2001 Ng Pheng Siong. All rights reserved.
#
# Permission to use, copy, modify, and distribute this software and its
# documentation for any purpose and without fee is hereby granted,
# provided that the above copyright notice appear in all copies and that
# both that copyright notice and this permission notice appear in
# supporting documentation.
from _pg import *
import select
import warnings
try:
frozenset
except NameError: # Python < 2.4, unsupported
from sets import ImmutableSet as frozenset
try:
from decimal import Decimal
set_decimal(Decimal)
except ImportError: # Python < 2.4, unsupported
Decimal = float
try:
from collections import namedtuple
except ImportError: # Python < 2.6
namedtuple = None
# Auxiliary functions that are independent from a DB connection:
def _is_quoted(s):
"""Check whether this string is a quoted identifier."""
s = s.replace('_', 'a')
return not s.isalnum() or s[:1].isdigit() or s != s.lower()
def _is_unquoted(s):
"""Check whether this string is an unquoted identifier."""
s = s.replace('_', 'a')
return s.isalnum() and not s[:1].isdigit()
def _split_first_part(s):
"""Split the first part of a dot separated string."""
s = s.lstrip()
if s[:1] == '"':
p = []
s = s.split('"', 3)[1:]
p.append(s[0])
while len(s) == 3 and s[1] == '':
p.append('"')
s = s[2].split('"', 2)
p.append(s[0])
p = [''.join(p)]
s = '"'.join(s[1:]).lstrip()
if s:
if s[:0] == '.':
p.append(s[1:])
else:
s = _split_first_part(s)
p[0] += s[0]
if len(s) > 1:
p.append(s[1])
else:
p = s.split('.', 1)
s = p[0].rstrip()
if _is_unquoted(s):
s = s.lower()
p[0] = s
return p
def _split_parts(s):
"""Split all parts of a dot separated string."""
q = []
while s:
s = _split_first_part(s)
q.append(s[0])
if len(s) < 2:
break
s = s[1]
return q
def _join_parts(s):
"""Join all parts of a dot separated string."""
return '.'.join([_is_quoted(p) and '"%s"' % p or p for p in s])
def _oid_key(qcl):
"""Build oid key from qualified class name."""
return 'oid(%s)' % qcl
if namedtuple:
def _namedresult(q):
"""Get query result as named tuples."""
row = namedtuple('Row', q.listfields())
return [row(*r) for r in q.getresult()]
set_namedresult(_namedresult)
def _db_error(msg, cls=DatabaseError):
"""Returns DatabaseError with empty sqlstate attribute."""
error = cls(msg)
error.sqlstate = None
return error
def _int_error(msg):
"""Returns InternalError."""
return _db_error(msg, InternalError)
def _prg_error(msg):
"""Returns ProgrammingError."""
return _db_error(msg, ProgrammingError)
# 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"' % (stop and self.stop_event or 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(object):
"""Wrapper class for the _pg connection type."""
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._closeable = True
else:
self._closeable = False
self.db = db
self.dbname = db.db
self._regtypes = False
self._attnames = {}
self._pkeys = {}
self._privileges = {}
self._args = args, kw
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')
# 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()
# Auxiliary methods
def _do_debug(self, s):
"""Print a debug message."""
if self.debug:
if isinstance(self.debug, basestring):
print(self.debug % s)
elif isinstance(self.debug, file):
self.debug.write(s + '\n')
elif callable(self.debug):
self.debug(s)
else:
print(s)
def _make_bool(d):
"""Get boolean value corresponding to d."""
if get_bool():
return bool(d)
return d and 't' or 'f'
_make_bool = staticmethod(_make_bool)
def _quote_text(self, d):
"""Quote text value."""
if not isinstance(d, basestring):
d = str(d)
return "'%s'" % self.escape_string(d)
_bool_true = frozenset('t true 1 y yes on'.split())
def _quote_bool(self, d):
"""Quote boolean value."""
if isinstance(d, basestring):
if not d:
return 'NULL'
d = d.lower() in self._bool_true
return d and "'t'" or "'f'"
_date_literals = frozenset('current_date current_time'
' current_timestamp localtime localtimestamp'.split())
def _quote_date(self, d):
"""Quote date value."""
if not d:
return 'NULL'
if isinstance(d, basestring) and d.lower() in self._date_literals:
return d
return self._quote_text(d)
def _quote_num(self, d):
"""Quote numeric value."""
if not d and d != 0:
return 'NULL'
return str(d)
def _quote_money(self, d):
"""Quote money value."""
if d is None or d == '':
return 'NULL'
if not isinstance(d, basestring):
d = str(d)
return d
_quote_funcs = dict( # quote methods for each type
text=_quote_text, bool=_quote_bool, date=_quote_date,
int=_quote_num, num=_quote_num, float=_quote_num,
money=_quote_money)
def _quote(self, d, t):
"""Return quotes if needed."""
if d is None:
return 'NULL'
try:
quote_func = self._quote_funcs[t]
except KeyError:
quote_func = self._quote_funcs['text']
return quote_func(self, d)
def _split_schema(self, cl):
"""Return schema and name of object separately.
This auxiliary function splits off the namespace (schema)
belonging to the class with the name cl. If the class name
is not qualified, the function is able to determine the schema
of the class, taking into account the current search path.
"""
s = _split_parts(cl)
if len(s) > 1: # name already qualified?
# should be database.schema.table or schema.table
if len(s) > 3:
raise _prg_error('Too many dots in class name %s' % cl)
schema, cl = s[-2:]
else:
cl = s[0]
# determine search path
q = 'SELECT current_schemas(TRUE)'
schemas = self.db.query(q).getresult()[0][0][1:-1].split(',')
if schemas: # non-empty path
# search schema for this object in the current search path
# (we could also use unnest with ordinality here to spare
# one query, but this is only possible since PostgreSQL 9.4)
q = ' UNION '.join(
["SELECT %d::integer AS n, '%s'::name AS nspname"
% s for s in enumerate(schemas)])
q = ("SELECT nspname FROM pg_class r"
" JOIN pg_namespace s ON r.relnamespace = s.oid"
" JOIN (%s) AS p USING (nspname)"
" WHERE r.relname = $1 ORDER BY n LIMIT 1" % q)
schema = self.db.query(q, (cl,)).getresult()
if schema: # schema found
schema = schema[0][0]
else: # object not found in current search path
schema = 'public'
else: # empty path
schema = 'public'
return schema, cl
def _add_schema(self, cl):
"""Ensure that the class name is prefixed with a schema name."""
return _join_parts(self._split_schema(cl))
# 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 close(self):
"""Close the database connection."""
# Wraps shared library function so we can track state.
if self._closeable:
if self.db:
self.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._args[0], **self._args[1])
if self.db:
self.db.close()
self.db = db
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')
if isinstance(values, dict):
params = {}
else:
params = []
for key in parameter:
if isinstance(key, basestring):
param = key.strip().lower()
else:
param = 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():
if isinstance(key, basestring):
param = key.strip().lower()
else:
param = 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 and ' LOCAL' or ''
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, qstr, *args):
"""Executes 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 pgqueryobject 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.
Note that the query string must not be passed as a unicode value,
but you can pass arguments as unicode values if they can be decoded
using the current client encoding.
"""
# Wraps shared library function for debugging.
if not self.db:
raise _int_error('Connection is not valid')
self._do_debug(qstr)
return self.db.query(qstr, args)
def pkey(self, cl, newpkey=None):
"""This method gets or sets the primary key of a class.
Composite primary keys are represented as frozensets. Note that
this raises a KeyError if the table does not have a primary key.
If newpkey is set and is not a dictionary then set that
value as the primary key of the class. If it is a dictionary
then replace the internal cache of primary keys with a copy of it.
"""
# First see if the caller is supplying a dictionary
if isinstance(newpkey, dict):
# make sure that all classes have a namespace
self._pkeys = dict([
('.' in cl and cl or 'public.' + cl, pkey)
for cl, pkey in newpkey.items()])
return self._pkeys
qcl = self._add_schema(cl) # build fully qualified class name
# Check if the caller is supplying a new primary key for the class
if newpkey:
self._pkeys[qcl] = newpkey
return newpkey
# Get all the primary keys at once
if qcl not in self._pkeys:
# if not found, check again in case it was added after we started
self._pkeys = {}
if self.server_version >= 80200:
# the ANY syntax works correctly only with PostgreSQL >= 8.2
any_indkey = "= ANY (i.indkey)"
else:
any_indkey = "IN (%s)" % ', '.join(
['i.indkey[%d]' % i for i in range(16)])
q = ("SELECT s.nspname, r.relname, a.attname"
" FROM pg_class r"
" JOIN pg_namespace s ON s.oid = r.relnamespace"
" AND s.nspname NOT SIMILAR"
" TO 'pg/_%|information/_schema' ESCAPE '/'"
" JOIN pg_attribute a ON a.attrelid = r.oid"
" AND NOT a.attisdropped"
" JOIN pg_index i ON i.indrelid = r.oid"
" AND i.indisprimary AND a.attnum " + any_indkey)
for r in self.db.query(q).getresult():
cl, pkey = _join_parts(r[:2]), r[2]
self._pkeys.setdefault(cl, []).append(pkey)
# (only) for composite primary keys, the values will be frozensets
for cl, pkey in self._pkeys.items():
self._pkeys[cl] = len(pkey) > 1 and frozenset(pkey) or pkey[0]
self._do_debug(self._pkeys)
# will raise an exception if primary key doesn't exist
return self._pkeys[qcl]
def get_databases(self):
"""Get list of databases in the system."""
return [s[0] for s in
self.db.query('SELECT datname FROM pg_database').getresult()]
def get_relations(self, kinds=None):
"""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.
"""
where = kinds and " AND r.relkind IN (%s)" % ','.join(
["'%s'" % k for k in kinds]) or ''
q = ("SELECT s.nspname, r.relname"
" FROM pg_class r"
" JOIN pg_namespace s ON s.oid = r.relnamespace"
" WHERE s.nspname NOT SIMILAR"
" TO 'pg/_%%|information/_schema' ESCAPE '/' %s"
" ORDER BY 1, 2") % where
return [_join_parts(r) for r in self.db.query(q).getresult()]
def get_tables(self):
"""Return list of tables in connected database."""
return self.get_relations('r')
def get_attnames(self, cl, newattnames=None):
"""Given the name of a table, digs out the set of attribute names.
Returns a dictionary of attribute names (the names are the keys,
the values are the names of the attributes' types).
If the optional newattnames exists, it must be a dictionary and
will become the new attribute names dictionary.
By default, only a limited number of simple types will be returned.
You can get the regular types after calling use_regtypes(True).
"""
if isinstance(newattnames, dict):
self._attnames = newattnames
return
elif newattnames:
raise _prg_error('If supplied, newattnames must be a dictionary')
cl = self._split_schema(cl) # split into schema and class
qcl = _join_parts(cl) # build fully qualified name
# May as well cache them:
if qcl in self._attnames:
return self._attnames[qcl]
if qcl not in self.get_relations('rv'):
raise _prg_error('Class %s does not exist' % qcl)
q = ("SELECT a.attname, t.typname%s"
" FROM pg_class r"
" JOIN pg_namespace s ON r.relnamespace = s.oid"
" JOIN pg_attribute a ON a.attrelid = r.oid"
" JOIN pg_type t ON t.oid = a.atttypid"
" WHERE s.nspname = $1 AND r.relname = $2"
" AND (a.attnum > 0 OR a.attname = 'oid')"
" AND NOT a.attisdropped") % (
self._regtypes and '::regtype' or '',)
q = self.db.query(q, cl).getresult()
if self._regtypes:
t = dict(q)
else:
t = {}
for att, typ in q:
if typ.startswith('bool'):
typ = 'bool'
elif typ.startswith('abstime'):
typ = 'date'
elif typ.startswith('date'):
typ = 'date'
elif typ.startswith('interval'):
typ = 'date'
elif typ.startswith('timestamp'):
typ = 'date'
elif typ.startswith('oid'):
typ = 'int'
elif typ.startswith('int'):
typ = 'int'
elif typ.startswith('float'):
typ = 'float'
elif typ.startswith('numeric'):
typ = 'num'
elif typ.startswith('money'):
typ = 'money'
else:
typ = 'text'
t[att] = typ
self._attnames[qcl] = t # cache it
return self._attnames[qcl]
def use_regtypes(self, regtypes=None):
"""Use regular type names instead of simplified type names."""
if regtypes is None:
return self._regtypes
else:
regtypes = bool(regtypes)
if regtypes != self._regtypes:
self._regtypes = regtypes
self._attnames.clear()
return regtypes
def has_table_privilege(self, cl, privilege='select'):
"""Check whether current user has specified table privilege."""
qcl = self._add_schema(cl)
privilege = privilege.lower()
try:
return self._privileges[(qcl, privilege)]
except KeyError:
q = "SELECT has_table_privilege($1, $2)"
q = self.db.query(q, (qcl, privilege))
ret = q.getresult()[0][0] == self._make_bool(True)
self._privileges[(qcl, privilege)] = ret
return ret
def get(self, cl, arg, 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 key specifies a unique row. If keyname is not specified
then the primary key for the table is used. If arg is a dictionary
then the value for the key is taken from it and it is modified to
include the new values, replacing existing values where necessary.
For a composite key, keyname can also be a sequence of key names.
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(schema.table).
"""
if cl.endswith('*'): # scan descendant tables?
cl = cl[:-1].rstrip() # need parent table name
# build qualified class name
qcl = self._add_schema(cl)
# To allow users to work with multiple tables,
# we munge the name of the "oid" key
qoid = _oid_key(qcl)
if not keyname:
# use the primary key by default
try:
keyname = self.pkey(qcl)
except KeyError:
raise _prg_error('Class %s has no primary key' % qcl)
# We want the oid for later updates if that isn't the key
if keyname == 'oid':
if isinstance(arg, dict):
if qoid not in arg:
raise _prg_error('%s not in arg' % qoid)
else:
arg = {qoid: arg}
where = 'oid = %s' % arg[qoid]
attnames = '*'
else:
attnames = self.get_attnames(qcl)
if isinstance(keyname, basestring):
keyname = (keyname,)
if not isinstance(arg, dict):
if len(keyname) > 1:
raise _prg_error('Composite key needs dict as arg')
arg = dict([(k, arg) for k in keyname])
where = ' AND '.join(['%s = %s'
% (k, self._quote(arg[k], attnames[k])) for k in keyname])
attnames = ', '.join(attnames)
q = 'SELECT %s FROM %s WHERE %s LIMIT 1' % (attnames, qcl, where)
self._do_debug(q)
res = self.db.query(q).dictresult()
if not res:
raise _db_error('No such record in %s where %s' % (qcl, where))
for att, value in res[0].items():
arg[att == 'oid' and qoid or att] = value
return arg
def insert(self, cl, d=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, if possible, reloaded with the values actually
inserted in order to pick up values modified by rules, triggers, etc.
"""
qcl = self._add_schema(cl)
qoid = _oid_key(qcl)
if d is None:
d = {}
d.update(kw)
attnames = self.get_attnames(qcl)
names, values = [], []
for n in attnames:
if n != 'oid' and n in d:
names.append('"%s"' % n)
values.append(self._quote(d[n], attnames[n]))
names, values = ', '.join(names), ', '.join(values)
selectable = self.has_table_privilege(qcl)
if selectable and self.server_version >= 80200:
ret = ' RETURNING %s*' % ('oid' in attnames and 'oid, ' or '')
else:
ret = ''
q = 'INSERT INTO %s (%s) VALUES (%s)%s' % (qcl, names, values, ret)
self._do_debug(q)
res = self.db.query(q)
if ret:
res = res.dictresult()
for att, value in res[0].items():
d[att == 'oid' and qoid or att] = value
elif isinstance(res, int):
d[qoid] = res
if selectable:
self.get(qcl, d, 'oid')
elif selectable:
if qoid in d:
self.get(qcl, d, 'oid')
else:
try:
self.get(qcl, d)
except ProgrammingError:
pass # table has no primary key
return d
def update(self, cl, d=None, **kw):
"""Update an existing row in a database table.
Similar to insert but updates an existing row. The update is based
on the OID value as munged by get() or passed as keyword, or on the
primary key of the table. The dictionary is modified, if possible,
to reflect any changes caused by the update due to triggers, rules,
default values, etc.
"""
# Update always works on the oid which get() returns if available,
# otherwise use the primary key. Fail if neither.
# Note that we only accept oid key from named args for safety.
qcl = self._add_schema(cl)
qoid = _oid_key(qcl)
if 'oid' in kw:
kw[qoid] = kw['oid']
del kw['oid']
if d is None:
d = {}
d.update(kw)
attnames = self.get_attnames(qcl)
if qoid in d:
where = 'oid = %s' % d[qoid]
keyname = ()
else:
try:
keyname = self.pkey(qcl)
except KeyError:
raise _prg_error('Class %s has no primary key' % qcl)
if isinstance(keyname, basestring):
keyname = (keyname,)
try:
where = ' AND '.join(['%s = %s'
% (k, self._quote(d[k], attnames[k])) for k in keyname])
except KeyError:
raise _prg_error('Update needs primary key or oid.')
values = []
for n in attnames:
if n in d and n not in keyname:
values.append('%s = %s' % (n, self._quote(d[n], attnames[n])))
if not values:
return d
values = ', '.join(values)
selectable = self.has_table_privilege(qcl)
if selectable and self.server_version >= 80200:
ret = ' RETURNING %s*' % ('oid' in attnames and 'oid, ' or '')
else:
ret = ''
q = 'UPDATE %s SET %s WHERE %s%s' % (qcl, values, where, ret)
self._do_debug(q)
res = self.db.query(q)
if ret:
res = res.dictresult()[0]
for att, value in res.items():
d[att == 'oid' and qoid or att] = value
else:
if selectable:
if qoid in d:
self.get(qcl, d, 'oid')
else:
self.get(qcl, d)
return d
def clear(self, cl, d=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 second 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.
qcl = self._add_schema(cl)
if d is None:
d = {} # empty if argument is not present
attnames = self.get_attnames(qcl)
for n, t in attnames.items():
if n == 'oid':
continue
if t in ('int', 'integer', 'smallint', 'bigint',
'float', 'real', 'double precision',
'num', 'numeric', 'money'):
d[n] = 0
elif t in ('bool', 'boolean'):
d[n] = self._make_bool(False)
else:
d[n] = ''
return d
def delete(self, cl, d=None, **kw):
"""Delete an existing row in a database table.
This method deletes the row from a table. It deletes based on the
OID value as munged by get() or passed as keyword, or on the primary
key of the table. 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).
"""
# Like update, delete works on the oid.
# One day we will be testing that the record to be deleted
# isn't referenced somewhere (or else PostgreSQL will).
# Note that we only accept oid key from named args for safety
qcl = self._add_schema(cl)
qoid = _oid_key(qcl)
if 'oid' in kw:
kw[qoid] = kw['oid']
del kw['oid']
if d is None:
d = {}
d.update(kw)
if qoid in d:
where = 'oid = %s' % d[qoid]
else:
try:
keyname = self.pkey(qcl)
except KeyError:
raise _prg_error('Class %s has no primary key' % qcl)
if isinstance(keyname, basestring):
keyname = (keyname,)
attnames = self.get_attnames(qcl)
try:
where = ' AND '.join(['%s = %s'
% (k, self._quote(d[k], attnames[k])) for k in keyname])
except KeyError:
raise _prg_error('Delete needs primary key or oid.')
q = 'DELETE FROM %s WHERE %s' % (qcl, where)
self._do_debug(q)
return int(self.db.query(q))
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._add_schema(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 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__)
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