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# engine/__init__.py
# Copyright (C) 2005-2019 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
"""SQL connections, SQL execution and high-level DB-API interface.
The engine package defines the basic components used to interface
DB-API modules with higher-level statement construction,
connection-management, execution and result contexts. The primary
"entry point" class into this package is the Engine and its public
constructor ``create_engine()``.
This package includes:
base.py
Defines interface classes and some implementation classes which
comprise the basic components used to interface between a DB-API,
constructed and plain-text statements, connections, transactions,
and results.
default.py
Contains default implementations of some of the components defined
in base.py. All current database dialects use the classes in
default.py as base classes for their own database-specific
implementations.
strategies.py
The mechanics of constructing ``Engine`` objects are represented
here. Defines the ``EngineStrategy`` class which represents how
to go from arguments specified to the ``create_engine()``
function, to a fully constructed ``Engine``, including
initialization of connection pooling, dialects, and specific
subclasses of ``Engine``.
threadlocal.py
The ``TLEngine`` class is defined here, which is a subclass of
the generic ``Engine`` and tracks ``Connection`` and
``Transaction`` objects against the identity of the current
thread. This allows certain programming patterns based around
the concept of a "thread-local connection" to be possible.
The ``TLEngine`` is created by using the "threadlocal" engine
strategy in conjunction with the ``create_engine()`` function.
url.py
Defines the ``URL`` class which represents the individual
components of a string URL passed to ``create_engine()``. Also
defines a basic module-loading strategy for the dialect specifier
within a URL.
"""
from . import strategies
from . import util # noqa
from .base import Connection # noqa
from .base import Engine # noqa
from .base import NestedTransaction # noqa
from .base import RootTransaction # noqa
from .base import Transaction # noqa
from .base import TwoPhaseTransaction # noqa
from .interfaces import Compiled # noqa
from .interfaces import Connectable # noqa
from .interfaces import CreateEnginePlugin # noqa
from .interfaces import Dialect # noqa
from .interfaces import ExceptionContext # noqa
from .interfaces import ExecutionContext # noqa
from .interfaces import TypeCompiler # noqa
from .result import BaseRowProxy # noqa
from .result import BufferedColumnResultProxy # noqa
from .result import BufferedColumnRow # noqa
from .result import BufferedRowResultProxy # noqa
from .result import FullyBufferedResultProxy # noqa
from .result import ResultProxy # noqa
from .result import RowProxy # noqa
from .util import connection_memoize # noqa
from ..sql import ddl # noqa
# backwards compat
default_strategy = "plain"
def create_engine(*args, **kwargs):
"""Create a new :class:`.Engine` instance.
The standard calling form is to send the URL as the
first positional argument, usually a string
that indicates database dialect and connection arguments::
engine = create_engine("postgresql://scott:tiger@localhost/test")
Additional keyword arguments may then follow it which
establish various options on the resulting :class:`.Engine`
and its underlying :class:`.Dialect` and :class:`.Pool`
constructs::
engine = create_engine("mysql://scott:tiger@hostname/dbname",
encoding='latin1', echo=True)
The string form of the URL is
``dialect[+driver]://user:password@host/dbname[?key=value..]``, where
``dialect`` is a database name such as ``mysql``, ``oracle``,
``postgresql``, etc., and ``driver`` the name of a DBAPI, such as
``psycopg2``, ``pyodbc``, ``cx_oracle``, etc. Alternatively,
the URL can be an instance of :class:`~sqlalchemy.engine.url.URL`.
``**kwargs`` takes a wide variety of options which are routed
towards their appropriate components. Arguments may be specific to
the :class:`.Engine`, the underlying :class:`.Dialect`, as well as the
:class:`.Pool`. Specific dialects also accept keyword arguments that
are unique to that dialect. Here, we describe the parameters
that are common to most :func:`.create_engine()` usage.
Once established, the newly resulting :class:`.Engine` will
request a connection from the underlying :class:`.Pool` once
:meth:`.Engine.connect` is called, or a method which depends on it
such as :meth:`.Engine.execute` is invoked. The :class:`.Pool` in turn
will establish the first actual DBAPI connection when this request
is received. The :func:`.create_engine` call itself does **not**
establish any actual DBAPI connections directly.
.. seealso::
:doc:`/core/engines`
:doc:`/dialects/index`
:ref:`connections_toplevel`
:param case_sensitive=True: if False, result column names
will match in a case-insensitive fashion, that is,
``row['SomeColumn']``.
:param connect_args: a dictionary of options which will be
passed directly to the DBAPI's ``connect()`` method as
additional keyword arguments. See the example
at :ref:`custom_dbapi_args`.
:param convert_unicode=False: if set to True, causes
all :class:`.String` datatypes to act as though the
:paramref:`.String.convert_unicode` flag has been set to ``True``,
regardless of a setting of ``False`` on an individual :class:`.String`
type. This has the effect of causing all :class:`.String` -based
columns to accommodate Python Unicode objects directly as though the
datatype were the :class:`.Unicode` type.
.. deprecated:: 1.3
The :paramref:`.create_engine.convert_unicode` parameter
is deprecated and will be removed in a future release.
All modern DBAPIs now support Python Unicode directly and this
parameter is unnecessary.
:param creator: a callable which returns a DBAPI connection.
This creation function will be passed to the underlying
connection pool and will be used to create all new database
connections. Usage of this function causes connection
parameters specified in the URL argument to be bypassed.
:param echo=False: if True, the Engine will log all statements
as well as a ``repr()`` of their parameter lists to the default log
handler, which defaults to ``sys.stdout`` for output. If set to the
string ``"debug"``, result rows will be printed to the standard output
as well. The ``echo`` attribute of ``Engine`` can be modified at any
time to turn logging on and off; direct control of logging is also
available using the standard Python ``logging`` module.
.. seealso::
:ref:`dbengine_logging` - further detail on how to configure
logging.
:param echo_pool=False: if True, the connection pool will log
informational output such as when connections are invalidated
as well as when connections are recycled to the default log handler,
which defaults to ``sys.stdout`` for output. If set to the string
``"debug"``, the logging will include pool checkouts and checkins.
Direct control of logging is also available using the standard Python
``logging`` module.
.. seealso::
:ref:`dbengine_logging` - further detail on how to configure
logging.
:param empty_in_strategy: The SQL compilation strategy to use when
rendering an IN or NOT IN expression for :meth:`.ColumnOperators.in_`
where the right-hand side
is an empty set. This is a string value that may be one of
``static``, ``dynamic``, or ``dynamic_warn``. The ``static``
strategy is the default, and an IN comparison to an empty set
will generate a simple false expression "1 != 1". The ``dynamic``
strategy behaves like that of SQLAlchemy 1.1 and earlier, emitting
a false expression of the form "expr != expr", which has the effect
of evaluting to NULL in the case of a null expression.
``dynamic_warn`` is the same as ``dynamic``, however also emits a
warning when an empty set is encountered; this because the "dynamic"
comparison is typically poorly performing on most databases.
.. versionadded:: 1.2 Added the ``empty_in_strategy`` setting and
additionally defaulted the behavior for empty-set IN comparisons
to a static boolean expression.
:param encoding: Defaults to ``utf-8``. This is the string
encoding used by SQLAlchemy for string encode/decode
operations which occur within SQLAlchemy, **outside of
the DBAPI.** Most modern DBAPIs feature some degree of
direct support for Python ``unicode`` objects,
what you see in Python 2 as a string of the form
``u'some string'``. For those scenarios where the
DBAPI is detected as not supporting a Python ``unicode``
object, this encoding is used to determine the
source/destination encoding. It is **not used**
for those cases where the DBAPI handles unicode
directly.
To properly configure a system to accommodate Python
``unicode`` objects, the DBAPI should be
configured to handle unicode to the greatest
degree as is appropriate - see
the notes on unicode pertaining to the specific
target database in use at :ref:`dialect_toplevel`.
Areas where string encoding may need to be accommodated
outside of the DBAPI include zero or more of:
* the values passed to bound parameters, corresponding to
the :class:`.Unicode` type or the :class:`.String` type
when ``convert_unicode`` is ``True``;
* the values returned in result set columns corresponding
to the :class:`.Unicode` type or the :class:`.String`
type when ``convert_unicode`` is ``True``;
* the string SQL statement passed to the DBAPI's
``cursor.execute()`` method;
* the string names of the keys in the bound parameter
dictionary passed to the DBAPI's ``cursor.execute()``
as well as ``cursor.setinputsizes()`` methods;
* the string column names retrieved from the DBAPI's
``cursor.description`` attribute.
When using Python 3, the DBAPI is required to support
*all* of the above values as Python ``unicode`` objects,
which in Python 3 are just known as ``str``. In Python 2,
the DBAPI does not specify unicode behavior at all,
so SQLAlchemy must make decisions for each of the above
values on a per-DBAPI basis - implementations are
completely inconsistent in their behavior.
:param execution_options: Dictionary execution options which will
be applied to all connections. See
:meth:`~sqlalchemy.engine.Connection.execution_options`
:param implicit_returning=True: When ``True``, a RETURNING-
compatible construct, if available, will be used to
fetch newly generated primary key values when a single row
INSERT statement is emitted with no existing returning()
clause. This applies to those backends which support RETURNING
or a compatible construct, including PostgreSQL, Firebird, Oracle,
Microsoft SQL Server. Set this to ``False`` to disable
the automatic usage of RETURNING.
:param isolation_level: this string parameter is interpreted by various
dialects in order to affect the transaction isolation level of the
database connection. The parameter essentially accepts some subset of
these string arguments: ``"SERIALIZABLE"``, ``"REPEATABLE_READ"``,
``"READ_COMMITTED"``, ``"READ_UNCOMMITTED"`` and ``"AUTOCOMMIT"``.
Behavior here varies per backend, and
individual dialects should be consulted directly.
Note that the isolation level can also be set on a
per-:class:`.Connection` basis as well, using the
:paramref:`.Connection.execution_options.isolation_level`
feature.
.. seealso::
:attr:`.Connection.default_isolation_level` - view default level
:paramref:`.Connection.execution_options.isolation_level`
- set per :class:`.Connection` isolation level
:ref:`SQLite Transaction Isolation <sqlite_isolation_level>`
:ref:`PostgreSQL Transaction Isolation <postgresql_isolation_level>`
:ref:`MySQL Transaction Isolation <mysql_isolation_level>`
:ref:`session_transaction_isolation` - for the ORM
:param label_length=None: optional integer value which limits
the size of dynamically generated column labels to that many
characters. If less than 6, labels are generated as
"_(counter)". If ``None``, the value of
``dialect.max_identifier_length`` is used instead.
:param listeners: A list of one or more
:class:`~sqlalchemy.interfaces.PoolListener` objects which will
receive connection pool events.
:param logging_name: String identifier which will be used within
the "name" field of logging records generated within the
"sqlalchemy.engine" logger. Defaults to a hexstring of the
object's id.
:param max_overflow=10: the number of connections to allow in
connection pool "overflow", that is connections that can be
opened above and beyond the pool_size setting, which defaults
to five. this is only used with :class:`~sqlalchemy.pool.QueuePool`.
:param module=None: reference to a Python module object (the module
itself, not its string name). Specifies an alternate DBAPI module to
be used by the engine's dialect. Each sub-dialect references a
specific DBAPI which will be imported before first connect. This
parameter causes the import to be bypassed, and the given module to
be used instead. Can be used for testing of DBAPIs as well as to
inject "mock" DBAPI implementations into the :class:`.Engine`.
:param paramstyle=None: The `paramstyle <http://legacy.python.org/dev/peps/pep-0249/#paramstyle>`_
to use when rendering bound parameters. This style defaults to the
one recommended by the DBAPI itself, which is retrieved from the
``.paramstyle`` attribute of the DBAPI. However, most DBAPIs accept
more than one paramstyle, and in particular it may be desirable
to change a "named" paramstyle into a "positional" one, or vice versa.
When this attribute is passed, it should be one of the values
``"qmark"``, ``"numeric"``, ``"named"``, ``"format"`` or
``"pyformat"``, and should correspond to a parameter style known
to be supported by the DBAPI in use.
:param pool=None: an already-constructed instance of
:class:`~sqlalchemy.pool.Pool`, such as a
:class:`~sqlalchemy.pool.QueuePool` instance. If non-None, this
pool will be used directly as the underlying connection pool
for the engine, bypassing whatever connection parameters are
present in the URL argument. For information on constructing
connection pools manually, see :ref:`pooling_toplevel`.
:param poolclass=None: a :class:`~sqlalchemy.pool.Pool`
subclass, which will be used to create a connection pool
instance using the connection parameters given in the URL. Note
this differs from ``pool`` in that you don't actually
instantiate the pool in this case, you just indicate what type
of pool to be used.
:param pool_logging_name: String identifier which will be used within
the "name" field of logging records generated within the
"sqlalchemy.pool" logger. Defaults to a hexstring of the object's
id.
:param pool_pre_ping: boolean, if True will enable the connection pool
"pre-ping" feature that tests connections for liveness upon
each checkout.
.. versionadded:: 1.2
.. seealso::
:ref:`pool_disconnects_pessimistic`
:param pool_size=5: the number of connections to keep open
inside the connection pool. This used with
:class:`~sqlalchemy.pool.QueuePool` as
well as :class:`~sqlalchemy.pool.SingletonThreadPool`. With
:class:`~sqlalchemy.pool.QueuePool`, a ``pool_size`` setting
of 0 indicates no limit; to disable pooling, set ``poolclass`` to
:class:`~sqlalchemy.pool.NullPool` instead.
:param pool_recycle=-1: this setting causes the pool to recycle
connections after the given number of seconds has passed. It
defaults to -1, or no timeout. For example, setting to 3600
means connections will be recycled after one hour. Note that
MySQL in particular will disconnect automatically if no
activity is detected on a connection for eight hours (although
this is configurable with the MySQLDB connection itself and the
server configuration as well).
.. seealso::
:ref:`pool_setting_recycle`
:param pool_reset_on_return='rollback': set the
:paramref:`.Pool.reset_on_return` parameter of the underlying
:class:`.Pool` object, which can be set to the values
``"rollback"``, ``"commit"``, or ``None``.
.. seealso::
:paramref:`.Pool.reset_on_return`
:param pool_timeout=30: number of seconds to wait before giving
up on getting a connection from the pool. This is only used
with :class:`~sqlalchemy.pool.QueuePool`.
:param pool_use_lifo=False: use LIFO (last-in-first-out) when retrieving
connections from :class:`.QueuePool` instead of FIFO
(first-in-first-out). Using LIFO, a server-side timeout scheme can
reduce the number of connections used during non- peak periods of
use. When planning for server-side timeouts, ensure that a recycle or
pre-ping strategy is in use to gracefully handle stale connections.
.. versionadded:: 1.3
.. seealso::
:ref:`pool_use_lifo`
:ref:`pool_disconnects`
:param plugins: string list of plugin names to load. See
:class:`.CreateEnginePlugin` for background.
.. versionadded:: 1.2.3
:param strategy='plain': selects alternate engine implementations.
Currently available are:
* the ``threadlocal`` strategy, which is described in
:ref:`threadlocal_strategy`;
* the ``mock`` strategy, which dispatches all statement
execution to a function passed as the argument ``executor``.
See `example in the FAQ
<http://docs.sqlalchemy.org/en/latest/faq/metadata_schema.html#how-can-i-get-the-create-table-drop-table-output-as-a-string>`_.
:param executor=None: a function taking arguments
``(sql, *multiparams, **params)``, to which the ``mock`` strategy will
dispatch all statement execution. Used only by ``strategy='mock'``.
""" # noqa
strategy = kwargs.pop("strategy", default_strategy)
strategy = strategies.strategies[strategy]
return strategy.create(*args, **kwargs)
def engine_from_config(configuration, prefix="sqlalchemy.", **kwargs):
"""Create a new Engine instance using a configuration dictionary.
The dictionary is typically produced from a config file.
The keys of interest to ``engine_from_config()`` should be prefixed, e.g.
``sqlalchemy.url``, ``sqlalchemy.echo``, etc. The 'prefix' argument
indicates the prefix to be searched for. Each matching key (after the
prefix is stripped) is treated as though it were the corresponding keyword
argument to a :func:`.create_engine` call.
The only required key is (assuming the default prefix) ``sqlalchemy.url``,
which provides the :ref:`database URL <database_urls>`.
A select set of keyword arguments will be "coerced" to their
expected type based on string values. The set of arguments
is extensible per-dialect using the ``engine_config_types`` accessor.
:param configuration: A dictionary (typically produced from a config file,
but this is not a requirement). Items whose keys start with the value
of 'prefix' will have that prefix stripped, and will then be passed to
:ref:`create_engine`.
:param prefix: Prefix to match and then strip from keys
in 'configuration'.
:param kwargs: Each keyword argument to ``engine_from_config()`` itself
overrides the corresponding item taken from the 'configuration'
dictionary. Keyword arguments should *not* be prefixed.
"""
options = dict(
(key[len(prefix) :], configuration[key])
for key in configuration
if key.startswith(prefix)
)
options["_coerce_config"] = True
options.update(kwargs)
url = options.pop("url")
return create_engine(url, **options)
__all__ = ("create_engine", "engine_from_config")

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# engine/strategies.py
# Copyright (C) 2005-2019 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
"""Strategies for creating new instances of Engine types.
These are semi-private implementation classes which provide the
underlying behavior for the "strategy" keyword argument available on
:func:`~sqlalchemy.engine.create_engine`. Current available options are
``plain``, ``threadlocal``, and ``mock``.
New strategies can be added via new ``EngineStrategy`` classes.
"""
from operator import attrgetter
from . import base
from . import threadlocal
from . import url
from .. import event
from .. import pool as poollib
from .. import util
from ..sql import schema
strategies = {}
class EngineStrategy(object):
"""An adaptor that processes input arguments and produces an Engine.
Provides a ``create`` method that receives input arguments and
produces an instance of base.Engine or a subclass.
"""
def __init__(self):
strategies[self.name] = self
def create(self, *args, **kwargs):
"""Given arguments, returns a new Engine instance."""
raise NotImplementedError()
class DefaultEngineStrategy(EngineStrategy):
"""Base class for built-in strategies."""
def create(self, name_or_url, **kwargs):
# create url.URL object
u = url.make_url(name_or_url)
plugins = u._instantiate_plugins(kwargs)
u.query.pop("plugin", None)
kwargs.pop("plugins", None)
entrypoint = u._get_entrypoint()
dialect_cls = entrypoint.get_dialect_cls(u)
if kwargs.pop("_coerce_config", False):
def pop_kwarg(key, default=None):
value = kwargs.pop(key, default)
if key in dialect_cls.engine_config_types:
value = dialect_cls.engine_config_types[key](value)
return value
else:
pop_kwarg = kwargs.pop
dialect_args = {}
# consume dialect arguments from kwargs
for k in util.get_cls_kwargs(dialect_cls):
if k in kwargs:
dialect_args[k] = pop_kwarg(k)
dbapi = kwargs.pop("module", None)
if dbapi is None:
dbapi_args = {}
for k in util.get_func_kwargs(dialect_cls.dbapi):
if k in kwargs:
dbapi_args[k] = pop_kwarg(k)
dbapi = dialect_cls.dbapi(**dbapi_args)
dialect_args["dbapi"] = dbapi
for plugin in plugins:
plugin.handle_dialect_kwargs(dialect_cls, dialect_args)
# create dialect
dialect = dialect_cls(**dialect_args)
# assemble connection arguments
(cargs, cparams) = dialect.create_connect_args(u)
cparams.update(pop_kwarg("connect_args", {}))
cargs = list(cargs) # allow mutability
# look for existing pool or create
pool = pop_kwarg("pool", None)
if pool is None:
def connect(connection_record=None):
if dialect._has_events:
for fn in dialect.dispatch.do_connect:
connection = fn(
dialect, connection_record, cargs, cparams
)
if connection is not None:
return connection
return dialect.connect(*cargs, **cparams)
creator = pop_kwarg("creator", connect)
poolclass = pop_kwarg("poolclass", None)
if poolclass is None:
poolclass = dialect_cls.get_pool_class(u)
pool_args = {"dialect": dialect}
# consume pool arguments from kwargs, translating a few of
# the arguments
translate = {
"logging_name": "pool_logging_name",
"echo": "echo_pool",
"timeout": "pool_timeout",
"recycle": "pool_recycle",
"events": "pool_events",
"use_threadlocal": "pool_threadlocal",
"reset_on_return": "pool_reset_on_return",
"pre_ping": "pool_pre_ping",
"use_lifo": "pool_use_lifo",
}
for k in util.get_cls_kwargs(poolclass):
tk = translate.get(k, k)
if tk in kwargs:
pool_args[k] = pop_kwarg(tk)
for plugin in plugins:
plugin.handle_pool_kwargs(poolclass, pool_args)
pool = poolclass(creator, **pool_args)
else:
if isinstance(pool, poollib.dbapi_proxy._DBProxy):
pool = pool.get_pool(*cargs, **cparams)
else:
pool = pool
pool._dialect = dialect
# create engine.
engineclass = self.engine_cls
engine_args = {}
for k in util.get_cls_kwargs(engineclass):
if k in kwargs:
engine_args[k] = pop_kwarg(k)
_initialize = kwargs.pop("_initialize", True)
# all kwargs should be consumed
if kwargs:
raise TypeError(
"Invalid argument(s) %s sent to create_engine(), "
"using configuration %s/%s/%s. Please check that the "
"keyword arguments are appropriate for this combination "
"of components."
% (
",".join("'%s'" % k for k in kwargs),
dialect.__class__.__name__,
pool.__class__.__name__,
engineclass.__name__,
)
)
engine = engineclass(pool, dialect, u, **engine_args)
if _initialize:
do_on_connect = dialect.on_connect()
if do_on_connect:
def on_connect(dbapi_connection, connection_record):
conn = getattr(
dbapi_connection, "_sqla_unwrap", dbapi_connection
)
if conn is None:
return
do_on_connect(conn)
event.listen(pool, "first_connect", on_connect)
event.listen(pool, "connect", on_connect)
def first_connect(dbapi_connection, connection_record):
c = base.Connection(
engine, connection=dbapi_connection, _has_events=False
)
c._execution_options = util.immutabledict()
dialect.initialize(c)
dialect.do_rollback(c.connection)
event.listen(pool, "first_connect", first_connect, once=True)
dialect_cls.engine_created(engine)
if entrypoint is not dialect_cls:
entrypoint.engine_created(engine)
for plugin in plugins:
plugin.engine_created(engine)
return engine
class PlainEngineStrategy(DefaultEngineStrategy):
"""Strategy for configuring a regular Engine."""
name = "plain"
engine_cls = base.Engine
PlainEngineStrategy()
class ThreadLocalEngineStrategy(DefaultEngineStrategy):
"""Strategy for configuring an Engine with threadlocal behavior."""
name = "threadlocal"
engine_cls = threadlocal.TLEngine
ThreadLocalEngineStrategy()
class MockEngineStrategy(EngineStrategy):
"""Strategy for configuring an Engine-like object with mocked execution.
Produces a single mock Connectable object which dispatches
statement execution to a passed-in function.
"""
name = "mock"
def create(self, name_or_url, executor, **kwargs):
# create url.URL object
u = url.make_url(name_or_url)
dialect_cls = u.get_dialect()
dialect_args = {}
# consume dialect arguments from kwargs
for k in util.get_cls_kwargs(dialect_cls):
if k in kwargs:
dialect_args[k] = kwargs.pop(k)
# create dialect
dialect = dialect_cls(**dialect_args)
return MockEngineStrategy.MockConnection(dialect, executor)
class MockConnection(base.Connectable):
def __init__(self, dialect, execute):
self._dialect = dialect
self.execute = execute
engine = property(lambda s: s)
dialect = property(attrgetter("_dialect"))
name = property(lambda s: s._dialect.name)
schema_for_object = schema._schema_getter(None)
def contextual_connect(self, **kwargs):
return self
def connect(self, **kwargs):
return self
def execution_options(self, **kw):
return self
def compiler(self, statement, parameters, **kwargs):
return self._dialect.compiler(
statement, parameters, engine=self, **kwargs
)
def create(self, entity, **kwargs):
kwargs["checkfirst"] = False
from sqlalchemy.engine import ddl
ddl.SchemaGenerator(self.dialect, self, **kwargs).traverse_single(
entity
)
def drop(self, entity, **kwargs):
kwargs["checkfirst"] = False
from sqlalchemy.engine import ddl
ddl.SchemaDropper(self.dialect, self, **kwargs).traverse_single(
entity
)
def _run_visitor(
self, visitorcallable, element, connection=None, **kwargs
):
kwargs["checkfirst"] = False
visitorcallable(self.dialect, self, **kwargs).traverse_single(
element
)
def execute(self, object_, *multiparams, **params):
raise NotImplementedError()
MockEngineStrategy()

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# engine/threadlocal.py
# Copyright (C) 2005-2019 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
"""Provides a thread-local transactional wrapper around the root Engine class.
The ``threadlocal`` module is invoked when using the
``strategy="threadlocal"`` flag with :func:`~sqlalchemy.engine.create_engine`.
This module is semi-private and is invoked automatically when the threadlocal
engine strategy is used.
"""
import weakref
from . import base
from .. import util
class TLConnection(base.Connection):
def __init__(self, *arg, **kw):
super(TLConnection, self).__init__(*arg, **kw)
self.__opencount = 0
def _increment_connect(self):
self.__opencount += 1
return self
def close(self):
if self.__opencount == 1:
base.Connection.close(self)
self.__opencount -= 1
def _force_close(self):
self.__opencount = 0
base.Connection.close(self)
class TLEngine(base.Engine):
"""An Engine that includes support for thread-local managed
transactions.
"""
_tl_connection_cls = TLConnection
@util.deprecated(
"1.3",
"The 'threadlocal' engine strategy is deprecated, and will be "
"removed in a future release. The strategy is no longer relevant "
"to modern usage patterns (including that of the ORM "
":class:`.Session` object) which make use of a :class:`.Connection` "
"object in order to invoke statements.",
)
def __init__(self, *args, **kwargs):
super(TLEngine, self).__init__(*args, **kwargs)
self._connections = util.threading.local()
def contextual_connect(self, **kw):
return self._contextual_connect(**kw)
def _contextual_connect(self, **kw):
if not hasattr(self._connections, "conn"):
connection = None
else:
connection = self._connections.conn()
if connection is None or connection.closed:
# guards against pool-level reapers, if desired.
# or not connection.connection.is_valid:
connection = self._tl_connection_cls(
self,
self._wrap_pool_connect(self.pool.connect, connection),
**kw
)
self._connections.conn = weakref.ref(connection)
return connection._increment_connect()
def begin_twophase(self, xid=None):
if not hasattr(self._connections, "trans"):
self._connections.trans = []
self._connections.trans.append(
self._contextual_connect().begin_twophase(xid=xid)
)
return self
def begin_nested(self):
if not hasattr(self._connections, "trans"):
self._connections.trans = []
self._connections.trans.append(
self._contextual_connect().begin_nested()
)
return self
def begin(self):
if not hasattr(self._connections, "trans"):
self._connections.trans = []
self._connections.trans.append(self._contextual_connect().begin())
return self
def __enter__(self):
return self
def __exit__(self, type_, value, traceback):
if type_ is None:
self.commit()
else:
self.rollback()
def prepare(self):
if (
not hasattr(self._connections, "trans")
or not self._connections.trans
):
return
self._connections.trans[-1].prepare()
def commit(self):
if (
not hasattr(self._connections, "trans")
or not self._connections.trans
):
return
trans = self._connections.trans.pop(-1)
trans.commit()
def rollback(self):
if (
not hasattr(self._connections, "trans")
or not self._connections.trans
):
return
trans = self._connections.trans.pop(-1)
trans.rollback()
def dispose(self):
self._connections = util.threading.local()
super(TLEngine, self).dispose()
@property
def closed(self):
return (
not hasattr(self._connections, "conn")
or self._connections.conn() is None
or self._connections.conn().closed
)
def close(self):
if not self.closed:
self._contextual_connect().close()
connection = self._connections.conn()
connection._force_close()
del self._connections.conn
self._connections.trans = []
def __repr__(self):
return "TLEngine(%r)" % self.url

310
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# engine/url.py
# Copyright (C) 2005-2019 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
"""Provides the :class:`~sqlalchemy.engine.url.URL` class which encapsulates
information about a database connection specification.
The URL object is created automatically when
:func:`~sqlalchemy.engine.create_engine` is called with a string
argument; alternatively, the URL is a public-facing construct which can
be used directly and is also accepted directly by ``create_engine()``.
"""
import re
from .interfaces import Dialect
from .. import exc
from .. import util
from ..dialects import plugins
from ..dialects import registry
class URL(object):
"""
Represent the components of a URL used to connect to a database.
This object is suitable to be passed directly to a
:func:`~sqlalchemy.create_engine` call. The fields of the URL are parsed
from a string by the :func:`.make_url` function. the string
format of the URL is an RFC-1738-style string.
All initialization parameters are available as public attributes.
:param drivername: the name of the database backend.
This name will correspond to a module in sqlalchemy/databases
or a third party plug-in.
:param username: The user name.
:param password: database password.
:param host: The name of the host.
:param port: The port number.
:param database: The database name.
:param query: A dictionary of options to be passed to the
dialect and/or the DBAPI upon connect.
"""
def __init__(
self,
drivername,
username=None,
password=None,
host=None,
port=None,
database=None,
query=None,
):
self.drivername = drivername
self.username = username
self.password_original = password
self.host = host
if port is not None:
self.port = int(port)
else:
self.port = None
self.database = database
self.query = query or {}
def __to_string__(self, hide_password=True):
s = self.drivername + "://"
if self.username is not None:
s += _rfc_1738_quote(self.username)
if self.password is not None:
s += ":" + (
"***" if hide_password else _rfc_1738_quote(self.password)
)
s += "@"
if self.host is not None:
if ":" in self.host:
s += "[%s]" % self.host
else:
s += self.host
if self.port is not None:
s += ":" + str(self.port)
if self.database is not None:
s += "/" + self.database
if self.query:
keys = list(self.query)
keys.sort()
s += "?" + "&".join(
"%s=%s" % (k, element)
for k in keys
for element in util.to_list(self.query[k])
)
return s
def __str__(self):
return self.__to_string__(hide_password=False)
def __repr__(self):
return self.__to_string__()
def __hash__(self):
return hash(str(self))
def __eq__(self, other):
return (
isinstance(other, URL)
and self.drivername == other.drivername
and self.username == other.username
and self.password == other.password
and self.host == other.host
and self.database == other.database
and self.query == other.query
and self.port == other.port
)
def __ne__(self, other):
return not self == other
@property
def password(self):
if self.password_original is None:
return None
else:
return util.text_type(self.password_original)
@password.setter
def password(self, password):
self.password_original = password
def get_backend_name(self):
if "+" not in self.drivername:
return self.drivername
else:
return self.drivername.split("+")[0]
def get_driver_name(self):
if "+" not in self.drivername:
return self.get_dialect().driver
else:
return self.drivername.split("+")[1]
def _instantiate_plugins(self, kwargs):
plugin_names = util.to_list(self.query.get("plugin", ()))
plugin_names += kwargs.get("plugins", [])
return [
plugins.load(plugin_name)(self, kwargs)
for plugin_name in plugin_names
]
def _get_entrypoint(self):
"""Return the "entry point" dialect class.
This is normally the dialect itself except in the case when the
returned class implements the get_dialect_cls() method.
"""
if "+" not in self.drivername:
name = self.drivername
else:
name = self.drivername.replace("+", ".")
cls = registry.load(name)
# check for legacy dialects that
# would return a module with 'dialect' as the
# actual class
if (
hasattr(cls, "dialect")
and isinstance(cls.dialect, type)
and issubclass(cls.dialect, Dialect)
):
return cls.dialect
else:
return cls
def get_dialect(self):
"""Return the SQLAlchemy database dialect class corresponding
to this URL's driver name.
"""
entrypoint = self._get_entrypoint()
dialect_cls = entrypoint.get_dialect_cls(self)
return dialect_cls
def translate_connect_args(self, names=[], **kw):
r"""Translate url attributes into a dictionary of connection arguments.
Returns attributes of this url (`host`, `database`, `username`,
`password`, `port`) as a plain dictionary. The attribute names are
used as the keys by default. Unset or false attributes are omitted
from the final dictionary.
:param \**kw: Optional, alternate key names for url attributes.
:param names: Deprecated. Same purpose as the keyword-based alternate
names, but correlates the name to the original positionally.
"""
translated = {}
attribute_names = ["host", "database", "username", "password", "port"]
for sname in attribute_names:
if names:
name = names.pop(0)
elif sname in kw:
name = kw[sname]
else:
name = sname
if name is not None and getattr(self, sname, False):
translated[name] = getattr(self, sname)
return translated
def make_url(name_or_url):
"""Given a string or unicode instance, produce a new URL instance.
The given string is parsed according to the RFC 1738 spec. If an
existing URL object is passed, just returns the object.
"""
if isinstance(name_or_url, util.string_types):
return _parse_rfc1738_args(name_or_url)
else:
return name_or_url
def _parse_rfc1738_args(name):
pattern = re.compile(
r"""
(?P<name>[\w\+]+)://
(?:
(?P<username>[^:/]*)
(?::(?P<password>.*))?
@)?
(?:
(?:
\[(?P<ipv6host>[^/]+)\] |
(?P<ipv4host>[^/:]+)
)?
(?::(?P<port>[^/]*))?
)?
(?:/(?P<database>.*))?
""",
re.X,
)
m = pattern.match(name)
if m is not None:
components = m.groupdict()
if components["database"] is not None:
tokens = components["database"].split("?", 2)
components["database"] = tokens[0]
if len(tokens) > 1:
query = {}
for key, value in util.parse_qsl(tokens[1]):
if util.py2k:
key = key.encode("ascii")
if key in query:
query[key] = util.to_list(query[key])
query[key].append(value)
else:
query[key] = value
else:
query = None
else:
query = None
components["query"] = query
if components["username"] is not None:
components["username"] = _rfc_1738_unquote(components["username"])
if components["password"] is not None:
components["password"] = _rfc_1738_unquote(components["password"])
ipv4host = components.pop("ipv4host")
ipv6host = components.pop("ipv6host")
components["host"] = ipv4host or ipv6host
name = components.pop("name")
return URL(name, **components)
else:
raise exc.ArgumentError(
"Could not parse rfc1738 URL from string '%s'" % name
)
def _rfc_1738_quote(text):
return re.sub(r"[:@/]", lambda m: "%%%X" % ord(m.group(0)), text)
def _rfc_1738_unquote(text):
return util.unquote(text)
def _parse_keyvalue_args(name):
m = re.match(r"(\w+)://(.*)", name)
if m is not None:
(name, args) = m.group(1, 2)
opts = dict(util.parse_qsl(args))
return URL(name, *opts)
else:
return None

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# engine/util.py
# Copyright (C) 2005-2019 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
from .. import util
def connection_memoize(key):
"""Decorator, memoize a function in a connection.info stash.
Only applicable to functions which take no arguments other than a
connection. The memo will be stored in ``connection.info[key]``.
"""
@util.decorator
def decorated(fn, self, connection):
connection = connection.connect()
try:
return connection.info[key]
except KeyError:
connection.info[key] = val = fn(self, connection)
return val
return decorated
def py_fallback():
def _distill_params(multiparams, params): # noqa
r"""Given arguments from the calling form \*multiparams, \**params,
return a list of bind parameter structures, usually a list of
dictionaries.
In the case of 'raw' execution which accepts positional parameters,
it may be a list of tuples or lists.
"""
if not multiparams:
if params:
return [params]
else:
return []
elif len(multiparams) == 1:
zero = multiparams[0]
if isinstance(zero, (list, tuple)):
if (
not zero
or hasattr(zero[0], "__iter__")
and not hasattr(zero[0], "strip")
):
# execute(stmt, [{}, {}, {}, ...])
# execute(stmt, [(), (), (), ...])
return zero
else:
# execute(stmt, ("value", "value"))
return [zero]
elif hasattr(zero, "keys"):
# execute(stmt, {"key":"value"})
return [zero]
else:
# execute(stmt, "value")
return [[zero]]
else:
if hasattr(multiparams[0], "__iter__") and not hasattr(
multiparams[0], "strip"
):
return multiparams
else:
return [multiparams]
return locals()
try:
from sqlalchemy.cutils import _distill_params # noqa
except ImportError:
globals().update(py_fallback())