# engine/default.py
# Copyright (C) 2005-2015 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
import random
from . import reflection, interfaces, result
from ..sql import compiler, expression
from .. import types as sqltypes
from .. import exc, util, pool, processors
import codecs
import weakref
from .. import event
AUTOCOMMIT_REGEXP = re.compile(
r'\s*(?:UPDATE|INSERT|CREATE|DELETE|DROP|ALTER)',
re.I | re.UNICODE)
class DefaultDialect(interfaces.Dialect):
"""Default implementation of Dialect"""
statement_compiler = compiler.SQLCompiler
ddl_compiler = compiler.DDLCompiler
type_compiler = compiler.GenericTypeCompiler
preparer = compiler.IdentifierPreparer
supports_alter = True
# the first value we'd get for an autoincrement
# column.
default_sequence_base = 1
# 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_right_nested_joins = True
supports_native_enum = False
supports_native_boolean = False
supports_simple_order_by_label = True
engine_config_types = util.immutabledict([
('convert_unicode', util.bool_or_str('force')),
('pool_timeout', util.asint),
('echo', util.bool_or_str('debug')),
('echo_pool', util.bool_or_str('debug')),
('pool_recycle', util.asint),
('pool_size', util.asint),
('max_overflow', util.asint),
('pool_threadlocal', util.asbool),
])
# if the NUMERIC type
# returns decimal.Decimal.
# *not* the FLOAT type however.
supports_native_decimal = False
if util.py3k:
supports_unicode_statements = True
supports_unicode_binds = True
returns_unicode_strings = True
description_encoding = None
else:
supports_unicode_statements = False
supports_unicode_binds = False
returns_unicode_strings = False
description_encoding = 'use_encoding'
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
supports_multivalues_insert = False
server_version_info = None
construct_arguments = None
"""Optional set of argument specifiers for various SQLAlchemy
constructs, typically schema items.
To implement, establish as a series of tuples, as in::
construct_arguments = [
(schema.Index, {
"using": False,
"where": None,
"ops": None
})
]
If the above construct is established on the Postgresql dialect,
the :class:`.Index` construct will now accept the keyword arguments
``postgresql_using``, ``postgresql_where``, nad ``postgresql_ops``.
Any other argument specified to the constructor of :class:`.Index`
which is prefixed with ``postgresql_`` will raise :class:`.ArgumentError`.
A dialect which does not include a ``construct_arguments`` member will
not participate in the argument validation system. For such a dialect,
any argument name is accepted by all participating constructs, within
the namespace of arguments prefixed with that dialect name. The rationale
here is so that third-party dialects that haven't yet implemented this
feature continue to function in the old way.
.. versionadded:: 0.9.2
.. seealso::
:class:`.DialectKWArgs` - implementing base class which consumes
:attr:`.DefaultDialect.construct_arguments`
"""
# 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
reflection_options = ()
dbapi_exception_translation_map = util.immutabledict()
"""mapping used in the extremely unusual case that a DBAPI's
published exceptions don't actually have the __name__ that they
are linked towards.
.. versionadded:: 1.0.5
"""
def __init__(self, convert_unicode=False,
encoding='utf-8', paramstyle=None, dbapi=None,
implicit_returning=None,
supports_right_nested_joins=None,
case_sensitive=True,
supports_native_boolean=None,
label_length=None, **kwargs):
if not getattr(self, 'ported_sqla_06', True):
util.warn(
"The %s dialect is not yet ported to the 0.6 format" %
self.name)
self.convert_unicode = convert_unicode
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 supports_right_nested_joins is not None:
self.supports_right_nested_joins = supports_right_nested_joins
if supports_native_boolean is not None:
self.supports_native_boolean = supports_native_boolean
self.case_sensitive = case_sensitive
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)
if self.description_encoding is not None and \
self._check_unicode_description(connection):
self._description_decoder = self.description_encoding = None
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, additional_tests=None):
if util.py2k and not self.supports_unicode_statements:
cast_to = util.binary_type
else:
cast_to = util.text_type
if self.positional:
parameters = self.execute_sequence_format()
else:
parameters = {}
def check_unicode(test):
statement = cast_to(
expression.select([test]).compile(dialect=self))
try:
cursor = connection.connection.cursor()
connection._cursor_execute(cursor, statement, parameters)
row = cursor.fetchone()
cursor.close()
except exc.DBAPIError as de:
# note that _cursor_execute() will have closed the cursor
# if an exception is thrown.
util.warn("Exception attempting to "
"detect unicode returns: %r" % de)
return False
else:
return isinstance(row[0], util.text_type)
tests = [
# detect plain VARCHAR
expression.cast(
expression.literal_column("'test plain returns'"),
sqltypes.VARCHAR(60)
),
# detect if there's an NVARCHAR type with different behavior
# available
expression.cast(
expression.literal_column("'test unicode returns'"),
sqltypes.Unicode(60)
),
]
if additional_tests:
tests += additional_tests
results = set([check_unicode(test) for test in tests])
if results.issuperset([True, False]):
return "conditional"
else:
return results == set([True])
def _check_unicode_description(self, connection):
# all DBAPIs on Py2K return cursor.description as encoded,
# until pypy2.1beta2 with sqlite, so let's just check it -
# it's likely others will start doing this too in Py2k.
if util.py2k and not self.supports_unicode_statements:
cast_to = util.binary_type
else:
cast_to = util.text_type
cursor = connection.connection.cursor()
try:
cursor.execute(
cast_to(
expression.select([
expression.literal_column("'x'").label("some_label")
]).compile(dialect=self)
)
)
return isinstance(cursor.description[0][0], util.text_type)
finally:
cursor.close()
def type_descriptor(self, typeobj):
"""Provide a database-specific :class:`.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 :func:`.types.adapt_type`.
"""
return sqltypes.adapt_type(typeobj, self.colspecs)
def reflecttable(
self, connection, table, include_columns, exclude_columns):
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):
"""Compatibility 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 set_engine_execution_options(self, engine, opts):
if 'isolation_level' in opts:
isolation_level = opts['isolation_level']
@event.listens_for(engine, "engine_connect")
def set_isolation(connection, branch):
if not branch:
self._set_connection_isolation(connection, isolation_level)
def set_connection_execution_options(self, connection, opts):
if 'isolation_level' in opts:
self._set_connection_isolation(connection, opts['isolation_level'])
def _set_connection_isolation(self, connection, level):
if connection.in_transaction():
util.warn(
"Connection is already established with a Transaction; "
"setting isolation_level may implicitly rollback or commit "
"the existing transaction, or have no effect until "
"next transaction")
self.set_isolation_level(connection.connection, level)
connection.connection._connection_record.\
finalize_callback.append(self.reset_isolation_level)
def do_begin(self, dbapi_connection):
pass
def do_rollback(self, dbapi_connection):
dbapi_connection.rollback()
def do_commit(self, dbapi_connection):
dbapi_connection.commit()
def do_close(self, dbapi_connection):
dbapi_connection.close()
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 connection
# 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(interfaces.ExecutionContext):
isinsert = False
isupdate = False
isdelete = False
is_crud = False
isddl = False
executemany = False
compiled = None
statement = None
result_column_struct = None
_is_implicit_returning = False
_is_explicit_returning = False
# a hook for SQLite's translation of
# result column names
_translate_colname = None
@classmethod
def _init_ddl(cls, dialect, connection, dbapi_connection, compiled_ddl):
"""Initialize execution context for a DDLElement construct."""
self = cls.__new__(cls)
self.root_connection = connection
self._dbapi_connection = dbapi_connection
self.dialect = connection.dialect
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 = util.text_type(compiled)
self.statement = dialect._encoder(self.unicode_statement)[0]
else:
self.statement = self.unicode_statement = util.text_type(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.root_connection = connection
self._dbapi_connection = dbapi_connection
self.dialect = connection.dialect
self.compiled = compiled
if not compiled.can_execute:
raise exc.ArgumentError("Not an executable clause")
self.execution_options = compiled.statement._execution_options.union(
connection._execution_options)
self.result_column_struct = (
compiled._result_columns, compiled._ordered_columns)
self.unicode_statement = util.text_type(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 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 or self.isdelete:
self.is_crud = True
self._is_explicit_returning = bool(compiled.statement._returning)
self._is_implicit_returning = bool(
compiled.returning and not compiled.statement._returning)
if not self.isdelete:
if self.compiled.prefetch:
if self.executemany:
self._process_executemany_defaults()
else:
self._process_executesingle_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:
if encode:
param = dict(
(
dialect._encoder(key)[0],
processors[key](compiled_params[key])
if key in processors
else compiled_params[key]
)
for key in compiled_params
)
else:
param = dict(
(
key,
processors[key](compiled_params[key])
if key in processors
else compiled_params[key]
)
for key in compiled_params
)
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.root_connection = connection
self._dbapi_connection = dbapi_connection
self.dialect = connection.dialect
# 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, util.text_type):
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.root_connection = connection
self._dbapi_connection = dbapi_connection
self.dialect = connection.dialect
self.execution_options = connection._execution_options
self.cursor = self.create_cursor()
return self
@util.memoized_property
def engine(self):
return self.root_connection.engine
@util.memoized_property
def postfetch_cols(self):
return self.compiled.postfetch
@util.memoized_property
def prefetch_cols(self):
return self.compiled.prefetch
@util.memoized_property
def returning_cols(self):
self.compiled.returning
@util.memoized_property
def no_parameters(self):
return self.execution_options.get("no_parameters", False)
@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, util.text_type) 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, context=self)
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_result_processor(self, type_, colname, coltype):
"""Return a 'result processor' for a given type as present in
cursor.description.
This has a default implementation that dialects can override
for context-sensitive result type handling.
"""
return type_._cached_result_processor(self.dialect, coltype)
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 result.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 _setup_crud_result_proxy(self):
if self.isinsert and \
not self.executemany:
if not self._is_implicit_returning and \
not self.compiled.inline and \
self.dialect.postfetch_lastrowid:
self._setup_ins_pk_from_lastrowid()
elif not self._is_implicit_returning:
self._setup_ins_pk_from_empty()
result = self.get_result_proxy()
if self.isinsert:
if self._is_implicit_returning:
row = result.fetchone()
self.returned_defaults = row
self._setup_ins_pk_from_implicit_returning(row)
result._soft_close(_autoclose_connection=False)
result._metadata = None
elif not self._is_explicit_returning:
result._soft_close(_autoclose_connection=False)
result._metadata = None
elif self.isupdate and self._is_implicit_returning:
row = result.fetchone()
self.returned_defaults = row
result._soft_close(_autoclose_connection=False)
result._metadata = None
elif result._metadata is None:
# no results, get rowcount
# (which requires open cursor on some drivers
# such as kintersbasdb, mxodbc)
result.rowcount
result._soft_close(_autoclose_connection=False)
return result
def _setup_ins_pk_from_lastrowid(self):
key_getter = self.compiled._key_getters_for_crud_column[2]
table = self.compiled.statement.table
compiled_params = self.compiled_parameters[0]
lastrowid = self.get_lastrowid()
if lastrowid is not None:
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 = [
lastrowid if c is autoinc_col else
compiled_params.get(key_getter(c), None)
for c in table.primary_key
]
else:
# don't have a usable lastrowid, so
# do the same as _setup_ins_pk_from_empty
self.inserted_primary_key = [
compiled_params.get(key_getter(c), None)
for c in table.primary_key
]
def _setup_ins_pk_from_empty(self):
key_getter = self.compiled._key_getters_for_crud_column[2]
table = self.compiled.statement.table
compiled_params = self.compiled_parameters[0]
self.inserted_primary_key = [
compiled_params.get(key_getter(c), None)
for c in table.primary_key
]
def _setup_ins_pk_from_implicit_returning(self, row):
key_getter = self.compiled._key_getters_for_crud_column[2]
table = self.compiled.statement.table
compiled_params = self.compiled_parameters[0]
self.inserted_primary_key = [
row[col] if value is None else value
for col, value in [
(col, compiled_params.get(key_getter(col), None))
for col in table.primary_key
]
]
def lastrow_has_defaults(self):
return (self.isinsert or self.isupdate) and \
bool(self.compiled.postfetch)
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 as e:
self.root_connection._handle_dbapi_exception(
e, None, None, None, self)
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)
if not self.dialect.supports_unicode_binds:
key = self.dialect._encoder(key)[0]
inputsizes[key] = dbtype
try:
self.cursor.setinputsizes(**inputsizes)
except Exception as e:
self.root_connection._handle_dbapi_exception(
e, None, None, None, self)
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_executemany_defaults(self):
key_getter = self.compiled._key_getters_for_crud_column[2]
prefetch = 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 prefetch:
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 prefetch:
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[key_getter(c)] = val
del self.current_parameters
def _process_executesingle_defaults(self):
key_getter = self.compiled._key_getters_for_crud_column[2]
prefetch = self.compiled.prefetch
self.current_parameters = compiled_parameters = \
self.compiled_parameters[0]
for c in prefetch:
if self.isinsert:
if c.default and \
not c.default.is_sequence and c.default.is_scalar:
val = c.default.arg
else:
val = self.get_insert_default(c)
else:
val = self.get_update_default(c)
if val is not None:
compiled_parameters[key_getter(c)] = val
del self.current_parameters
DefaultDialect.execution_ctx_cls = DefaultExecutionContext