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CouchPotatoServer/libs/sqlalchemy/engine/default.py

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# engine/default.py
# Copyright (C) 2005-2012 the SQLAlchemy authors and contributors <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""Default implementations of per-dialect sqlalchemy.engine classes.
These are semi-private implementation classes which are only of importance
to database dialect authors; dialects will usually use the classes here
as the base class for their own corresponding classes.
"""
import re, random
from sqlalchemy.engine import base, reflection
from sqlalchemy.sql import compiler, expression
from sqlalchemy import exc, types as sqltypes, util, pool, processors
import codecs
import weakref
AUTOCOMMIT_REGEXP = re.compile(
r'\s*(?:UPDATE|INSERT|CREATE|DELETE|DROP|ALTER)',
re.I | re.UNICODE)
class DefaultDialect(base.Dialect):
"""Default implementation of Dialect"""
statement_compiler = compiler.SQLCompiler
ddl_compiler = compiler.DDLCompiler
type_compiler = compiler.GenericTypeCompiler
preparer = compiler.IdentifierPreparer
supports_alter = True
# most DBAPIs happy with this for execute().
# not cx_oracle.
execute_sequence_format = tuple
supports_views = True
supports_sequences = False
sequences_optional = False
preexecute_autoincrement_sequences = False
postfetch_lastrowid = True
implicit_returning = False
supports_native_enum = False
supports_native_boolean = False
# if the NUMERIC type
# returns decimal.Decimal.
# *not* the FLOAT type however.
supports_native_decimal = False
# Py3K
#supports_unicode_statements = True
#supports_unicode_binds = True
#returns_unicode_strings = True
#description_encoding = None
# Py2K
supports_unicode_statements = False
supports_unicode_binds = False
returns_unicode_strings = False
description_encoding = 'use_encoding'
# end Py2K
name = 'default'
# length at which to truncate
# any identifier.
max_identifier_length = 9999
# length at which to truncate
# the name of an index.
# Usually None to indicate
# 'use max_identifier_length'.
# thanks to MySQL, sigh
max_index_name_length = None
supports_sane_rowcount = True
supports_sane_multi_rowcount = True
dbapi_type_map = {}
colspecs = {}
default_paramstyle = 'named'
supports_default_values = False
supports_empty_insert = True
server_version_info = None
# indicates symbol names are
# UPPERCASEd if they are case insensitive
# within the database.
# if this is True, the methods normalize_name()
# and denormalize_name() must be provided.
requires_name_normalize = False
# a hook for SQLite's translation of
# result column names
_translate_colname = None
reflection_options = ()
def __init__(self, convert_unicode=False, assert_unicode=False,
encoding='utf-8', paramstyle=None, dbapi=None,
implicit_returning=None,
label_length=None, **kwargs):
if not getattr(self, 'ported_sqla_06', True):
util.warn(
"The %s dialect is not yet ported to SQLAlchemy 0.6/0.7" %
self.name)
self.convert_unicode = convert_unicode
if assert_unicode:
util.warn_deprecated(
"assert_unicode is deprecated. "
"SQLAlchemy emits a warning in all cases where it "
"would otherwise like to encode a Python unicode object "
"into a specific encoding but a plain bytestring is "
"received. "
"This does *not* apply to DBAPIs that coerce Unicode "
"natively.")
self.encoding = encoding
self.positional = False
self._ischema = None
self.dbapi = dbapi
if paramstyle is not None:
self.paramstyle = paramstyle
elif self.dbapi is not None:
self.paramstyle = self.dbapi.paramstyle
else:
self.paramstyle = self.default_paramstyle
if implicit_returning is not None:
self.implicit_returning = implicit_returning
self.positional = self.paramstyle in ('qmark', 'format', 'numeric')
self.identifier_preparer = self.preparer(self)
self.type_compiler = self.type_compiler(self)
if label_length and label_length > self.max_identifier_length:
raise exc.ArgumentError(
"Label length of %d is greater than this dialect's"
" maximum identifier length of %d" %
(label_length, self.max_identifier_length))
self.label_length = label_length
if self.description_encoding == 'use_encoding':
self._description_decoder = processors.to_unicode_processor_factory(
encoding
)
elif self.description_encoding is not None:
self._description_decoder = processors.to_unicode_processor_factory(
self.description_encoding
)
self._encoder = codecs.getencoder(self.encoding)
self._decoder = processors.to_unicode_processor_factory(self.encoding)
@util.memoized_property
def _type_memos(self):
return weakref.WeakKeyDictionary()
@property
def dialect_description(self):
return self.name + "+" + self.driver
@classmethod
def get_pool_class(cls, url):
return getattr(cls, 'poolclass', pool.QueuePool)
def initialize(self, connection):
try:
self.server_version_info = \
self._get_server_version_info(connection)
except NotImplementedError:
self.server_version_info = None
try:
self.default_schema_name = \
self._get_default_schema_name(connection)
except NotImplementedError:
self.default_schema_name = None
try:
self.default_isolation_level = \
self.get_isolation_level(connection.connection)
except NotImplementedError:
self.default_isolation_level = None
self.returns_unicode_strings = self._check_unicode_returns(connection)
self.do_rollback(connection.connection)
def on_connect(self):
"""return a callable which sets up a newly created DBAPI connection.
This is used to set dialect-wide per-connection options such as
isolation modes, unicode modes, etc.
If a callable is returned, it will be assembled into a pool listener
that receives the direct DBAPI connection, with all wrappers removed.
If None is returned, no listener will be generated.
"""
return None
def _check_unicode_returns(self, connection):
# Py2K
if self.supports_unicode_statements:
cast_to = unicode
else:
cast_to = str
# end Py2K
# Py3K
#cast_to = str
def check_unicode(formatstr, type_):
cursor = connection.connection.cursor()
try:
try:
cursor.execute(
cast_to(
expression.select(
[expression.cast(
expression.literal_column(
"'test %s returns'" % formatstr), type_)
]).compile(dialect=self)
)
)
row = cursor.fetchone()
return isinstance(row[0], unicode)
except self.dbapi.Error, de:
util.warn("Exception attempting to "
"detect unicode returns: %r" % de)
return False
finally:
cursor.close()
# detect plain VARCHAR
unicode_for_varchar = check_unicode("plain", sqltypes.VARCHAR(60))
# detect if there's an NVARCHAR type with different behavior available
unicode_for_unicode = check_unicode("unicode", sqltypes.Unicode(60))
if unicode_for_unicode and not unicode_for_varchar:
return "conditional"
else:
return unicode_for_varchar
def type_descriptor(self, typeobj):
"""Provide a database-specific ``TypeEngine`` object, given
the generic object which comes from the types module.
This method looks for a dictionary called
``colspecs`` as a class or instance-level variable,
and passes on to ``types.adapt_type()``.
"""
return sqltypes.adapt_type(typeobj, self.colspecs)
def reflecttable(self, connection, table, include_columns, exclude_columns=None):
insp = reflection.Inspector.from_engine(connection)
return insp.reflecttable(table, include_columns, exclude_columns)
def get_pk_constraint(self, conn, table_name, schema=None, **kw):
"""Compatiblity method, adapts the result of get_primary_keys()
for those dialects which don't implement get_pk_constraint().
"""
return {
'constrained_columns':
self.get_primary_keys(conn, table_name,
schema=schema, **kw)
}
def validate_identifier(self, ident):
if len(ident) > self.max_identifier_length:
raise exc.IdentifierError(
"Identifier '%s' exceeds maximum length of %d characters" %
(ident, self.max_identifier_length)
)
def connect(self, *cargs, **cparams):
return self.dbapi.connect(*cargs, **cparams)
def create_connect_args(self, url):
opts = url.translate_connect_args()
opts.update(url.query)
return [[], opts]
def do_begin(self, connection):
"""Implementations might want to put logic here for turning
autocommit on/off, etc.
"""
pass
def do_rollback(self, connection):
"""Implementations might want to put logic here for turning
autocommit on/off, etc.
"""
connection.rollback()
def do_commit(self, connection):
"""Implementations might want to put logic here for turning
autocommit on/off, etc.
"""
connection.commit()
def create_xid(self):
"""Create a random two-phase transaction ID.
This id will be passed to do_begin_twophase(), do_rollback_twophase(),
do_commit_twophase(). Its format is unspecified.
"""
return "_sa_%032x" % random.randint(0, 2 ** 128)
def do_savepoint(self, connection, name):
connection.execute(expression.SavepointClause(name))
def do_rollback_to_savepoint(self, connection, name):
connection.execute(expression.RollbackToSavepointClause(name))
def do_release_savepoint(self, connection, name):
connection.execute(expression.ReleaseSavepointClause(name))
def do_executemany(self, cursor, statement, parameters, context=None):
cursor.executemany(statement, parameters)
def do_execute(self, cursor, statement, parameters, context=None):
cursor.execute(statement, parameters)
def do_execute_no_params(self, cursor, statement, context=None):
cursor.execute(statement)
def is_disconnect(self, e, connection, cursor):
return False
def reset_isolation_level(self, dbapi_conn):
# default_isolation_level is read from the first conenction
# after the initial set of 'isolation_level', if any, so is
# the configured default of this dialect.
self.set_isolation_level(dbapi_conn, self.default_isolation_level)
class DefaultExecutionContext(base.ExecutionContext):
isinsert = False
isupdate = False
isdelete = False
isddl = False
executemany = False
result_map = None
compiled = None
statement = None
_is_implicit_returning = False
_is_explicit_returning = False
@classmethod
def _init_ddl(cls, dialect, connection, dbapi_connection, compiled_ddl):
"""Initialize execution context for a DDLElement construct."""
self = cls.__new__(cls)
self.dialect = dialect
self.root_connection = connection
self._dbapi_connection = dbapi_connection
self.engine = connection.engine
self.compiled = compiled = compiled_ddl
self.isddl = True
self.execution_options = compiled.statement._execution_options
if connection._execution_options:
self.execution_options = dict(self.execution_options)
self.execution_options.update(connection._execution_options)
if not dialect.supports_unicode_statements:
self.unicode_statement = unicode(compiled)
self.statement = dialect._encoder(self.unicode_statement)[0]
else:
self.statement = self.unicode_statement = unicode(compiled)
self.cursor = self.create_cursor()
self.compiled_parameters = []
if dialect.positional:
self.parameters = [dialect.execute_sequence_format()]
else:
self.parameters = [{}]
return self
@classmethod
def _init_compiled(cls, dialect, connection, dbapi_connection, compiled, parameters):
"""Initialize execution context for a Compiled construct."""
self = cls.__new__(cls)
self.dialect = dialect
self.root_connection = connection
self._dbapi_connection = dbapi_connection
self.engine = connection.engine
self.compiled = compiled
if not compiled.can_execute:
raise exc.ArgumentError("Not an executable clause")
self.execution_options = compiled.statement._execution_options
if connection._execution_options:
self.execution_options = dict(self.execution_options)
self.execution_options.update(connection._execution_options)
# compiled clauseelement. process bind params, process table defaults,
# track collections used by ResultProxy to target and process results
self.result_map = compiled.result_map
self.unicode_statement = unicode(compiled)
if not dialect.supports_unicode_statements:
self.statement = self.unicode_statement.encode(self.dialect.encoding)
else:
self.statement = self.unicode_statement
self.isinsert = compiled.isinsert
self.isupdate = compiled.isupdate
self.isdelete = compiled.isdelete
if self.isinsert or self.isupdate or self.isdelete:
self._is_explicit_returning = compiled.statement._returning
self._is_implicit_returning = compiled.returning and \
not compiled.statement._returning
if not parameters:
self.compiled_parameters = [compiled.construct_params()]
else:
self.compiled_parameters = \
[compiled.construct_params(m, _group_number=grp) for
grp,m in enumerate(parameters)]
self.executemany = len(parameters) > 1
self.cursor = self.create_cursor()
if self.isinsert or self.isupdate:
self.postfetch_cols = self.compiled.postfetch
self.prefetch_cols = self.compiled.prefetch
self.__process_defaults()
processors = compiled._bind_processors
# Convert the dictionary of bind parameter values
# into a dict or list to be sent to the DBAPI's
# execute() or executemany() method.
parameters = []
if dialect.positional:
for compiled_params in self.compiled_parameters:
param = []
for key in self.compiled.positiontup:
if key in processors:
param.append(processors[key](compiled_params[key]))
else:
param.append(compiled_params[key])
parameters.append(dialect.execute_sequence_format(param))
else:
encode = not dialect.supports_unicode_statements
for compiled_params in self.compiled_parameters:
param = {}
if encode:
for key in compiled_params:
if key in processors:
param[dialect._encoder(key)[0]] = \
processors[key](compiled_params[key])
else:
param[dialect._encoder(key)[0]] = compiled_params[key]
else:
for key in compiled_params:
if key in processors:
param[key] = processors[key](compiled_params[key])
else:
param[key] = compiled_params[key]
parameters.append(param)
self.parameters = dialect.execute_sequence_format(parameters)
return self
@classmethod
def _init_statement(cls, dialect, connection, dbapi_connection, statement, parameters):
"""Initialize execution context for a string SQL statement."""
self = cls.__new__(cls)
self.dialect = dialect
self.root_connection = connection
self._dbapi_connection = dbapi_connection
self.engine = connection.engine
# plain text statement
self.execution_options = connection._execution_options
if not parameters:
if self.dialect.positional:
self.parameters = [dialect.execute_sequence_format()]
else:
self.parameters = [{}]
elif isinstance(parameters[0], dialect.execute_sequence_format):
self.parameters = parameters
elif isinstance(parameters[0], dict):
if dialect.supports_unicode_statements:
self.parameters = parameters
else:
self.parameters= [
dict((dialect._encoder(k)[0], d[k]) for k in d)
for d in parameters
] or [{}]
else:
self.parameters = [dialect.execute_sequence_format(p)
for p in parameters]
self.executemany = len(parameters) > 1
if not dialect.supports_unicode_statements and isinstance(statement, unicode):
self.unicode_statement = statement
self.statement = dialect._encoder(statement)[0]
else:
self.statement = self.unicode_statement = statement
self.cursor = self.create_cursor()
return self
@classmethod
def _init_default(cls, dialect, connection, dbapi_connection):
"""Initialize execution context for a ColumnDefault construct."""
self = cls.__new__(cls)
self.dialect = dialect
self.root_connection = connection
self._dbapi_connection = dbapi_connection
self.engine = connection.engine
self.execution_options = connection._execution_options
self.cursor = self.create_cursor()
return self
@util.memoized_property
def no_parameters(self):
return self.execution_options.get("no_parameters", False)
@util.memoized_property
def is_crud(self):
return self.isinsert or self.isupdate or self.isdelete
@util.memoized_property
def should_autocommit(self):
autocommit = self.execution_options.get('autocommit',
not self.compiled and
self.statement and
expression.PARSE_AUTOCOMMIT
or False)
if autocommit is expression.PARSE_AUTOCOMMIT:
return self.should_autocommit_text(self.unicode_statement)
else:
return autocommit
def _execute_scalar(self, stmt, type_):
"""Execute a string statement on the current cursor, returning a
scalar result.
Used to fire off sequences, default phrases, and "select lastrowid"
types of statements individually or in the context of a parent INSERT
or UPDATE statement.
"""
conn = self.root_connection
if isinstance(stmt, unicode) and \
not self.dialect.supports_unicode_statements:
stmt = self.dialect._encoder(stmt)[0]
if self.dialect.positional:
default_params = self.dialect.execute_sequence_format()
else:
default_params = {}
conn._cursor_execute(self.cursor, stmt, default_params)
r = self.cursor.fetchone()[0]
if type_ is not None:
# apply type post processors to the result
proc = type_._cached_result_processor(
self.dialect,
self.cursor.description[0][1]
)
if proc:
return proc(r)
return r
@property
def connection(self):
return self.root_connection._branch()
def should_autocommit_text(self, statement):
return AUTOCOMMIT_REGEXP.match(statement)
def create_cursor(self):
return self._dbapi_connection.cursor()
def pre_exec(self):
pass
def post_exec(self):
pass
def get_lastrowid(self):
"""return self.cursor.lastrowid, or equivalent, after an INSERT.
This may involve calling special cursor functions,
issuing a new SELECT on the cursor (or a new one),
or returning a stored value that was
calculated within post_exec().
This function will only be called for dialects
which support "implicit" primary key generation,
keep preexecute_autoincrement_sequences set to False,
and when no explicit id value was bound to the
statement.
The function is called once, directly after
post_exec() and before the transaction is committed
or ResultProxy is generated. If the post_exec()
method assigns a value to `self._lastrowid`, the
value is used in place of calling get_lastrowid().
Note that this method is *not* equivalent to the
``lastrowid`` method on ``ResultProxy``, which is a
direct proxy to the DBAPI ``lastrowid`` accessor
in all cases.
"""
return self.cursor.lastrowid
def handle_dbapi_exception(self, e):
pass
def get_result_proxy(self):
return base.ResultProxy(self)
@property
def rowcount(self):
return self.cursor.rowcount
def supports_sane_rowcount(self):
return self.dialect.supports_sane_rowcount
def supports_sane_multi_rowcount(self):
return self.dialect.supports_sane_multi_rowcount
def post_insert(self):
if not self._is_implicit_returning and \
self.dialect.postfetch_lastrowid and \
(not self.inserted_primary_key or \
None in self.inserted_primary_key):
table = self.compiled.statement.table
lastrowid = self.get_lastrowid()
autoinc_col = table._autoincrement_column
if autoinc_col is not None:
# apply type post processors to the lastrowid
proc = autoinc_col.type._cached_result_processor(self.dialect, None)
if proc is not None:
lastrowid = proc(lastrowid)
self.inserted_primary_key = [
c is autoinc_col and lastrowid or v
for c, v in zip(
table.primary_key,
self.inserted_primary_key)
]
def _fetch_implicit_returning(self, resultproxy):
table = self.compiled.statement.table
row = resultproxy.fetchone()
ipk = []
for c, v in zip(table.primary_key, self.inserted_primary_key):
if v is not None:
ipk.append(v)
else:
ipk.append(row[c])
self.inserted_primary_key = ipk
def lastrow_has_defaults(self):
return (self.isinsert or self.isupdate) and \
bool(self.postfetch_cols)
def set_input_sizes(self, translate=None, exclude_types=None):
"""Given a cursor and ClauseParameters, call the appropriate
style of ``setinputsizes()`` on the cursor, using DB-API types
from the bind parameter's ``TypeEngine`` objects.
This method only called by those dialects which require it,
currently cx_oracle.
"""
if not hasattr(self.compiled, 'bind_names'):
return
types = dict(
(self.compiled.bind_names[bindparam], bindparam.type)
for bindparam in self.compiled.bind_names)
if self.dialect.positional:
inputsizes = []
for key in self.compiled.positiontup:
typeengine = types[key]
dbtype = typeengine.dialect_impl(self.dialect).get_dbapi_type(self.dialect.dbapi)
if dbtype is not None and (not exclude_types or dbtype not in exclude_types):
inputsizes.append(dbtype)
try:
self.cursor.setinputsizes(*inputsizes)
except Exception, e:
self.root_connection._handle_dbapi_exception(e, None, None, None, self)
raise
else:
inputsizes = {}
for key in self.compiled.bind_names.values():
typeengine = types[key]
dbtype = typeengine.dialect_impl(self.dialect).get_dbapi_type(self.dialect.dbapi)
if dbtype is not None and (not exclude_types or dbtype not in exclude_types):
if translate:
key = translate.get(key, key)
inputsizes[self.dialect._encoder(key)[0]] = dbtype
try:
self.cursor.setinputsizes(**inputsizes)
except Exception, e:
self.root_connection._handle_dbapi_exception(e, None, None, None, self)
raise
def _exec_default(self, default, type_):
if default.is_sequence:
return self.fire_sequence(default, type_)
elif default.is_callable:
return default.arg(self)
elif default.is_clause_element:
# TODO: expensive branching here should be
# pulled into _exec_scalar()
conn = self.connection
c = expression.select([default.arg]).compile(bind=conn)
return conn._execute_compiled(c, (), {}).scalar()
else:
return default.arg
def get_insert_default(self, column):
if column.default is None:
return None
else:
return self._exec_default(column.default, column.type)
def get_update_default(self, column):
if column.onupdate is None:
return None
else:
return self._exec_default(column.onupdate, column.type)
def __process_defaults(self):
"""Generate default values for compiled insert/update statements,
and generate inserted_primary_key collection.
"""
if self.executemany:
if len(self.compiled.prefetch):
scalar_defaults = {}
# pre-determine scalar Python-side defaults
# to avoid many calls of get_insert_default()/
# get_update_default()
for c in self.prefetch_cols:
if self.isinsert and c.default and c.default.is_scalar:
scalar_defaults[c] = c.default.arg
elif self.isupdate and c.onupdate and c.onupdate.is_scalar:
scalar_defaults[c] = c.onupdate.arg
for param in self.compiled_parameters:
self.current_parameters = param
for c in self.prefetch_cols:
if c in scalar_defaults:
val = scalar_defaults[c]
elif self.isinsert:
val = self.get_insert_default(c)
else:
val = self.get_update_default(c)
if val is not None:
param[c.key] = val
del self.current_parameters
else:
self.current_parameters = compiled_parameters = \
self.compiled_parameters[0]
for c in self.compiled.prefetch:
if self.isinsert:
val = self.get_insert_default(c)
else:
val = self.get_update_default(c)
if val is not None:
compiled_parameters[c.key] = val
del self.current_parameters
if self.isinsert:
self.inserted_primary_key = [
self.compiled_parameters[0].get(c.key, None)
for c in self.compiled.\
statement.table.primary_key
]
DefaultDialect.execution_ctx_cls = DefaultExecutionContext