Current File : //opt/cloudlinux/venv/lib/python3.11/site-packages/sqlalchemy/engine/default.py
# engine/default.py
# Copyright (C) 2005-2021 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 codecs
import random
import re
import weakref
from . import interfaces
from . import reflection
from . import result
from .. import event
from .. import exc
from .. import pool
from .. import processors
from .. import types as sqltypes
from .. import util
from ..sql import compiler
from ..sql import expression
from ..sql import schema
from ..sql.elements import quoted_name
AUTOCOMMIT_REGEXP = re.compile(
r"\s*(?:UPDATE|INSERT|CREATE|DELETE|DROP|ALTER)", re.I | re.UNICODE
)
# When we're handed literal SQL, ensure it's a SELECT query
SERVER_SIDE_CURSOR_RE = re.compile(r"\s*SELECT", 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
supports_comments = False
inline_comments = False
# 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
cte_follows_insert = False
supports_native_enum = False
supports_native_boolean = False
non_native_boolean_check_constraint = True
supports_simple_order_by_label = True
tuple_in_values = False
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
_user_defined_max_identifier_length = None
# sub-categories of max_identifier_length.
# currently these accommodate for MySQL which allows alias names
# of 255 but DDL names only of 64.
max_index_name_length = None
max_constraint_name_length = None
supports_sane_rowcount = True
supports_sane_multi_rowcount = True
colspecs = {}
default_paramstyle = "named"
supports_default_values = False
supports_empty_insert = True
supports_multivalues_insert = False
supports_is_distinct_from = True
supports_server_side_cursors = False
# extra record-level locking features (#4860)
supports_for_update_of = 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
"""
@util.deprecated_params(
convert_unicode=(
"1.3",
"The :paramref:`_sa.create_engine.convert_unicode` parameter "
"and corresponding dialect-level parameters are deprecated, "
"and will be removed in a future release. Modern DBAPIs support "
"Python Unicode natively and this parameter is unnecessary.",
)
)
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,
empty_in_strategy="static",
max_identifier_length=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
self.empty_in_strategy = empty_in_strategy
if empty_in_strategy == "static":
self._use_static_in = True
elif empty_in_strategy in ("dynamic", "dynamic_warn"):
self._use_static_in = False
self._warn_on_empty_in = empty_in_strategy == "dynamic_warn"
else:
raise exc.ArgumentError(
"empty_in_strategy may be 'static', "
"'dynamic', or 'dynamic_warn'"
)
self._user_defined_max_identifier_length = max_identifier_length
if self._user_defined_max_identifier_length:
self.max_identifier_length = (
self._user_defined_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
@property
def supports_sane_rowcount_returning(self):
"""True if this dialect supports sane rowcount even if RETURNING is
in use.
For dialects that don't support RETURNING, this is synonymous with
``supports_sane_rowcount``.
"""
return self.supports_sane_rowcount
@classmethod
def get_pool_class(cls, url):
return getattr(cls, "poolclass", pool.QueuePool)
@classmethod
def load_provisioning(cls):
package = ".".join(cls.__module__.split(".")[0:-1])
try:
__import__(package + ".provision")
except ImportError:
pass
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_default_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
if not self._user_defined_max_identifier_length:
max_ident_length = self._check_max_identifier_length(connection)
if max_ident_length:
self.max_identifier_length = max_ident_length
if (
self.label_length
and self.label_length > self.max_identifier_length
):
raise exc.ArgumentError(
"Label length of %d is greater than this dialect's"
" maximum identifier length of %d"
% (self.label_length, self.max_identifier_length)
)
def on_connect(self):
# inherits the docstring from interfaces.Dialect.on_connect
return None
def _check_max_identifier_length(self, connection):
"""Perform a connection / server version specific check to determine
the max_identifier_length.
If the dialect's class level max_identifier_length should be used,
can return None.
.. versionadded:: 1.3.9
"""
return None
def get_default_isolation_level(self, dbapi_conn):
"""Given a DBAPI connection, return its isolation level, or
a default isolation level if one cannot be retrieved.
May be overridden by subclasses in order to provide a
"fallback" isolation level for databases that cannot reliably
retrieve the actual isolation level.
By default, calls the :meth:`_engine.Interfaces.get_isolation_level`
method, propagating any exceptions raised.
.. versionadded:: 1.3.22
"""
return self.get_isolation_level(dbapi_conn)
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 = {check_unicode(test) for test in tests}
if results.issuperset([True, False]):
return "conditional"
else:
return results == {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,
resolve_fks,
**opts
):
insp = reflection.Inspector.from_engine(connection)
return insp.reflecttable(
table, include_columns, exclude_columns, resolve_fks, **opts
)
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):
# inherits the docstring from interfaces.Dialect.connect
return self.dbapi.connect(*cargs, **cparams)
def create_connect_args(self, url):
# inherits the docstring from interfaces.Dialect.create_connect_args
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)
if "schema_translate_map" in opts:
getter = schema._schema_getter(opts["schema_translate_map"])
engine.schema_for_object = getter
@event.listens_for(engine, "engine_connect")
def set_schema_translate_map(connection, branch):
connection.schema_for_object = getter
def set_connection_execution_options(self, connection, opts):
if "isolation_level" in opts:
self._set_connection_isolation(connection, opts["isolation_level"])
if "schema_translate_map" in opts:
getter = schema._schema_getter(opts["schema_translate_map"])
connection.schema_for_object = getter
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()
@util.memoized_property
def _dialect_specific_select_one(self):
return str(expression.select([1]).compile(dialect=self))
def do_ping(self, dbapi_connection):
cursor = None
try:
cursor = dbapi_connection.cursor()
try:
cursor.execute(self._dialect_specific_select_one)
finally:
cursor.close()
except self.dbapi.Error as err:
if self.is_disconnect(err, dbapi_connection, cursor):
return False
else:
raise
else:
return True
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)
def normalize_name(self, name):
if name is None:
return None
if util.py2k:
if isinstance(name, str):
name = name.decode(self.encoding)
name_lower = name.lower()
name_upper = name.upper()
if name_upper == name_lower:
# name has no upper/lower conversion, e.g. non-european characters.
# return unchanged
return name
elif name_upper == name and not (
self.identifier_preparer._requires_quotes
)(name_lower):
# name is all uppercase and doesn't require quoting; normalize
# to all lower case
return name_lower
elif name_lower == name:
# name is all lower case, which if denormalized means we need to
# force quoting on it
return quoted_name(name, quote=True)
else:
# name is mixed case, means it will be quoted in SQL when used
# later, no normalizes
return name
def denormalize_name(self, name):
if name is None:
return None
name_lower = name.lower()
name_upper = name.upper()
if name_upper == name_lower:
# name has no upper/lower conversion, e.g. non-european characters.
# return unchanged
return name
elif name_lower == name and not (
self.identifier_preparer._requires_quotes
)(name_lower):
name = name_upper
if util.py2k:
if not self.supports_unicode_binds:
name = name.encode(self.encoding)
else:
name = unicode(name) # noqa
return name
class _RendersLiteral(object):
def literal_processor(self, dialect):
def process(value):
return "'%s'" % value
return process
class _StrDateTime(_RendersLiteral, sqltypes.DateTime):
pass
class _StrDate(_RendersLiteral, sqltypes.Date):
pass
class _StrTime(_RendersLiteral, sqltypes.Time):
pass
class StrCompileDialect(DefaultDialect):
statement_compiler = compiler.StrSQLCompiler
ddl_compiler = compiler.DDLCompiler
type_compiler = compiler.StrSQLTypeCompiler
preparer = compiler.IdentifierPreparer
supports_sequences = True
sequences_optional = True
preexecute_autoincrement_sequences = False
implicit_returning = False
supports_native_boolean = True
supports_simple_order_by_label = True
colspecs = {
sqltypes.DateTime: _StrDateTime,
sqltypes.Date: _StrDate,
sqltypes.Time: _StrTime,
}
class DefaultExecutionContext(interfaces.ExecutionContext):
isinsert = False
isupdate = False
isdelete = False
is_crud = False
is_text = False
isddl = False
executemany = False
compiled = None
statement = None
result_column_struct = None
returned_defaults = None
_is_implicit_returning = False
_is_explicit_returning = False
# a hook for SQLite's translation of
# result column names
_translate_colname = None
_expanded_parameters = util.immutabledict()
@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.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
# this should be caught in the engine before
# we get here
assert compiled.can_execute
self.execution_options = compiled.execution_options.union(
connection._execution_options
)
self.result_column_struct = (
compiled._result_columns,
compiled._ordered_columns,
compiled._textual_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
self.is_text = compiled.isplaintext
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 self.compiled.insert_prefetch or self.compiled.update_prefetch:
if self.executemany:
self._process_executemany_defaults()
else:
self._process_executesingle_defaults()
processors = compiled._bind_processors
if compiled.contains_expanding_parameters:
# copy processors for this case as they will be mutated
processors = dict(processors)
positiontup = self._expand_in_parameters(compiled, processors)
elif compiled.positional:
positiontup = self.compiled.positiontup
# 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 compiled.positional:
for compiled_params in self.compiled_parameters:
param = []
for key in 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
def _expand_in_parameters(self, compiled, processors):
"""handle special 'expanding' parameters, IN tuples that are rendered
on a per-parameter basis for an otherwise fixed SQL statement string.
"""
if self.executemany:
raise exc.InvalidRequestError(
"'expanding' parameters can't be used with " "executemany()"
)
if self.compiled.positional and self.compiled._numeric_binds:
# I'm not familiar with any DBAPI that uses 'numeric'
raise NotImplementedError(
"'expanding' bind parameters not supported with "
"'numeric' paramstyle at this time."
)
self._expanded_parameters = {}
compiled_params = self.compiled_parameters[0]
if compiled.positional:
positiontup = []
else:
positiontup = None
replacement_expressions = {}
to_update_sets = {}
for name in (
self.compiled.positiontup
if compiled.positional
else self.compiled.binds
):
parameter = self.compiled.binds[name]
if parameter.expanding:
if name in replacement_expressions:
to_update = to_update_sets[name]
else:
# we are removing the parameter from compiled_params
# because it is a list value, which is not expected by
# TypeEngine objects that would otherwise be asked to
# process it. the single name is being replaced with
# individual numbered parameters for each value in the
# param.
values = compiled_params.pop(name)
if not values:
to_update = to_update_sets[name] = []
replacement_expressions[
name
] = self.compiled.visit_empty_set_expr(
parameter._expanding_in_types
if parameter._expanding_in_types
else [parameter.type]
)
elif isinstance(values[0], (tuple, list)):
to_update = to_update_sets[name] = [
("%s_%s_%s" % (name, i, j), value)
for i, tuple_element in enumerate(values, 1)
for j, value in enumerate(tuple_element, 1)
]
replacement_expressions[name] = (
"VALUES " if self.dialect.tuple_in_values else ""
) + ", ".join(
"(%s)"
% ", ".join(
self.compiled.bindtemplate
% {
"name": to_update[
i * len(tuple_element) + j
][0]
}
for j, value in enumerate(tuple_element)
)
for i, tuple_element in enumerate(values)
)
else:
to_update = to_update_sets[name] = [
("%s_%s" % (name, i), value)
for i, value in enumerate(values, 1)
]
replacement_expressions[name] = ", ".join(
self.compiled.bindtemplate % {"name": key}
for key, value in to_update
)
compiled_params.update(to_update)
processors.update(
(key, processors[name])
for key, value in to_update
if name in processors
)
if compiled.positional:
positiontup.extend(name for name, value in to_update)
self._expanded_parameters[name] = [
expand_key for expand_key, value in to_update
]
elif compiled.positional:
positiontup.append(name)
def process_expanding(m):
return replacement_expressions[m.group(1)]
self.statement = re.sub(
r"\[EXPANDING_(\S+)\]", process_expanding, self.statement
)
return positiontup
@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
self.is_text = True
# 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 = [
{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 identifier_preparer(self):
if self.compiled:
return self.compiled.preparer
elif "schema_translate_map" in self.execution_options:
return self.dialect.identifier_preparer._with_schema_translate(
self.execution_options["schema_translate_map"]
)
else:
return self.dialect.identifier_preparer
@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):
if self.isinsert:
return self.compiled.insert_prefetch
elif self.isupdate:
return self.compiled.update_prefetch
else:
return ()
@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 _use_server_side_cursor(self):
if not self.dialect.supports_server_side_cursors:
return False
if self.dialect.server_side_cursors:
use_server_side = self.execution_options.get(
"stream_results", True
) and (
(
self.compiled
and isinstance(
self.compiled.statement, expression.Selectable
)
or (
(
not self.compiled
or isinstance(
self.compiled.statement, expression.TextClause
)
)
and self.statement
and SERVER_SIDE_CURSOR_RE.match(self.statement)
)
)
)
else:
use_server_side = self.execution_options.get(
"stream_results", False
)
return use_server_side
def create_cursor(self):
if self._use_server_side_cursor():
self._is_server_side = True
return self.create_server_side_cursor()
else:
self._is_server_side = False
return self._dbapi_connection.cursor()
def create_server_side_cursor(self):
raise NotImplementedError()
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):
if self._is_server_side:
return result.BufferedRowResultProxy(self)
else:
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()
result._metadata = None
elif not self._is_explicit_returning:
result._soft_close()
result._metadata = None
elif self.isupdate and self._is_implicit_returning:
row = result.fetchone()
self.returned_defaults = row
result._soft_close()
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()
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):
if row is None:
self.inserted_primary_key = None
return
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, include_types=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
inputsizes = {}
for bindparam in self.compiled.bind_names:
dialect_impl = bindparam.type._unwrapped_dialect_impl(self.dialect)
dialect_impl_cls = type(dialect_impl)
dbtype = dialect_impl.get_dbapi_type(self.dialect.dbapi)
if (
dbtype is not None
and (
not exclude_types
or dbtype not in exclude_types
and dialect_impl_cls not in exclude_types
)
and (
not include_types
or dbtype in include_types
or dialect_impl_cls in include_types
)
):
inputsizes[bindparam] = dbtype
else:
inputsizes[bindparam] = None
if self.dialect._has_events:
self.dialect.dispatch.do_setinputsizes(
inputsizes, self.cursor, self.statement, self.parameters, self
)
if self.dialect.positional:
positional_inputsizes = []
for key in self.compiled.positiontup:
bindparam = self.compiled.binds[key]
dbtype = inputsizes.get(bindparam, None)
if dbtype is not None:
if key in self._expanded_parameters:
positional_inputsizes.extend(
[dbtype] * len(self._expanded_parameters[key])
)
else:
positional_inputsizes.append(dbtype)
try:
self.cursor.setinputsizes(*positional_inputsizes)
except BaseException as e:
self.root_connection._handle_dbapi_exception(
e, None, None, None, self
)
else:
keyword_inputsizes = {}
for bindparam, key in self.compiled.bind_names.items():
dbtype = inputsizes.get(bindparam, None)
if dbtype is not None:
if translate:
# TODO: this part won't work w/ the
# expanded_parameters feature, e.g. for cx_oracle
# quoted bound names
key = translate.get(key, key)
if not self.dialect.supports_unicode_binds:
key = self.dialect._encoder(key)[0]
if key in self._expanded_parameters:
keyword_inputsizes.update(
(expand_key, dbtype)
for expand_key in self._expanded_parameters[key]
)
else:
keyword_inputsizes[key] = dbtype
try:
self.cursor.setinputsizes(**keyword_inputsizes)
except BaseException as e:
self.root_connection._handle_dbapi_exception(
e, None, None, None, self
)
def _exec_default(self, column, default, type_):
if default.is_sequence:
return self.fire_sequence(default, type_)
elif default.is_callable:
self.current_column = column
return default.arg(self)
elif default.is_clause_element:
# TODO: expensive branching here should be
# pulled into _exec_scalar()
conn = self.connection
if not default._arg_is_typed:
default_arg = expression.type_coerce(default.arg, type_)
else:
default_arg = default.arg
c = expression.select([default_arg]).compile(bind=conn)
return conn._execute_compiled(c, (), {}).scalar()
else:
return default.arg
current_parameters = None
"""A dictionary of parameters applied to the current row.
This attribute is only available in the context of a user-defined default
generation function, e.g. as described at :ref:`context_default_functions`.
It consists of a dictionary which includes entries for each column/value
pair that is to be part of the INSERT or UPDATE statement. The keys of the
dictionary will be the key value of each :class:`_schema.Column`,
which is usually
synonymous with the name.
Note that the :attr:`.DefaultExecutionContext.current_parameters` attribute
does not accommodate for the "multi-values" feature of the
:meth:`_expression.Insert.values` method. The
:meth:`.DefaultExecutionContext.get_current_parameters` method should be
preferred.
.. seealso::
:meth:`.DefaultExecutionContext.get_current_parameters`
:ref:`context_default_functions`
"""
def get_current_parameters(self, isolate_multiinsert_groups=True):
"""Return a dictionary of parameters applied to the current row.
This method can only be used in the context of a user-defined default
generation function, e.g. as described at
:ref:`context_default_functions`. When invoked, a dictionary is
returned which includes entries for each column/value pair that is part
of the INSERT or UPDATE statement. The keys of the dictionary will be
the key value of each :class:`_schema.Column`,
which is usually synonymous
with the name.
:param isolate_multiinsert_groups=True: indicates that multi-valued
INSERT constructs created using :meth:`_expression.Insert.values`
should be
handled by returning only the subset of parameters that are local
to the current column default invocation. When ``False``, the
raw parameters of the statement are returned including the
naming convention used in the case of multi-valued INSERT.
.. versionadded:: 1.2 added
:meth:`.DefaultExecutionContext.get_current_parameters`
which provides more functionality over the existing
:attr:`.DefaultExecutionContext.current_parameters`
attribute.
.. seealso::
:attr:`.DefaultExecutionContext.current_parameters`
:ref:`context_default_functions`
"""
try:
parameters = self.current_parameters
column = self.current_column
except AttributeError:
raise exc.InvalidRequestError(
"get_current_parameters() can only be invoked in the "
"context of a Python side column default function"
)
if (
isolate_multiinsert_groups
and self.isinsert
and self.compiled.statement._has_multi_parameters
):
if column._is_multiparam_column:
index = column.index + 1
d = {column.original.key: parameters[column.key]}
else:
d = {column.key: parameters[column.key]}
index = 0
keys = self.compiled.statement.parameters[0].keys()
d.update(
(key, parameters["%s_m%d" % (key, index)]) for key in keys
)
return d
else:
return parameters
def get_insert_default(self, column):
if column.default is None:
return None
else:
return self._exec_default(column, column.default, column.type)
def get_update_default(self, column):
if column.onupdate is None:
return None
else:
return self._exec_default(column, column.onupdate, column.type)
def _process_executemany_defaults(self):
key_getter = self.compiled._key_getters_for_crud_column[2]
scalar_defaults = {}
insert_prefetch = self.compiled.insert_prefetch
update_prefetch = self.compiled.update_prefetch
# pre-determine scalar Python-side defaults
# to avoid many calls of get_insert_default()/
# get_update_default()
for c in insert_prefetch:
if c.default and c.default.is_scalar:
scalar_defaults[c] = c.default.arg
for c in update_prefetch:
if 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 insert_prefetch:
if c in scalar_defaults:
val = scalar_defaults[c]
else:
val = self.get_insert_default(c)
if val is not None:
param[key_getter(c)] = val
for c in update_prefetch:
if c in scalar_defaults:
val = scalar_defaults[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]
self.current_parameters = (
compiled_parameters
) = self.compiled_parameters[0]
for c in self.compiled.insert_prefetch:
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)
if val is not None:
compiled_parameters[key_getter(c)] = val
for c in self.compiled.update_prefetch:
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
Mini Shell