File: //opt/alt/python37/lib64/python3.7/site-packages/sqlalchemy/orm/__pycache__/session.cpython-37.pyc
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mZ ddlmZ ddlmZ ddlmZ ddlmZ ddlmZ ddlm Z ddl m Z ddlm Z ddlm Z ddd d gZ!e�"� Z#d d � Z$G d d!� d!e%�Z&e �'d"�Z(e �'d#�Z)e �'d$�Z*e �'d%�Z+e �'d&�Z,G d'd� de%�Z-G d(d� de&�Z.G d)d � d e&�Z/d*d+� Z0d,d-� Z1d.d/� Z2d0d1� Z3e �4� Z5dS )2z1Provides the Session class and related utilities.� N� )�
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expression�Session�SessionTransactionr � sessionmakerc C s* | j r&y
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deprecatedr% Z dependenciesr& r) r r r r r" : s r" �ACTIVE�PREPARED� COMMITTED�DEACTIVE�CLOSEDc @ s� e Zd ZdZdZd+dd�Zedd� �ZdZedd � �Z d,d d �Z
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d� �Z d-dd�Z d.dd�Z
d/dd�Zdd� Zd0dd�Zdd� Zdd � Zd d � Zd d � Zd!d"� Zd1d#d$�Zd2d%d&�Zd'd(� Zd)d*� ZdS )3r a� A :class:`.Session`-level transaction.
:class:`.SessionTransaction` is a mostly behind-the-scenes object
not normally referenced directly by application code. It coordinates
among multiple :class:`.Connection` objects, maintaining a database
transaction for each one individually, committing or rolling them
back all at once. It also provides optional two-phase commit behavior
which can augment this coordination operation.
The :attr:`.Session.transaction` attribute of :class:`.Session`
refers to the current :class:`.SessionTransaction` object in use, if any.
The :attr:`.SessionTransaction.parent` attribute refers to the parent
:class:`.SessionTransaction` in the stack of :class:`.SessionTransaction`
objects. If this attribute is ``None``, then this is the top of the stack.
If non-``None``, then this :class:`.SessionTransaction` refers either
to a so-called "subtransaction" or a "nested" transaction. A
"subtransaction" is a scoping concept that demarcates an inner portion
of the outermost "real" transaction. A nested transaction, which
is indicated when the :attr:`.SessionTransaction.nested`
attribute is also True, indicates that this :class:`.SessionTransaction`
corresponds to a SAVEPOINT.
**Life Cycle**
A :class:`.SessionTransaction` is associated with a :class:`.Session`
in its default mode of ``autocommit=False`` immediately, associated
with no database connections. As the :class:`.Session` is called upon
to emit SQL on behalf of various :class:`.Engine` or :class:`.Connection`
objects, a corresponding :class:`.Connection` and associated
:class:`.Transaction` is added to a collection within the
:class:`.SessionTransaction` object, becoming one of the
connection/transaction pairs maintained by the
:class:`.SessionTransaction`. The start of a :class:`.SessionTransaction`
can be tracked using the :meth:`.SessionEvents.after_transaction_create`
event.
The lifespan of the :class:`.SessionTransaction` ends when the
:meth:`.Session.commit`, :meth:`.Session.rollback` or
:meth:`.Session.close` methods are called. At this point, the
:class:`.SessionTransaction` removes its association with its parent
:class:`.Session`. A :class:`.Session` that is in ``autocommit=False``
mode will create a new :class:`.SessionTransaction` to replace it
immediately, whereas a :class:`.Session` that's in ``autocommit=True``
mode will remain without a :class:`.SessionTransaction` until the
:meth:`.Session.begin` method is called. The end of a
:class:`.SessionTransaction` can be tracked using the
:meth:`.SessionEvents.after_transaction_end` event.
**Nesting and Subtransactions**
Another detail of :class:`.SessionTransaction` behavior is that it is
capable of "nesting". This means that the :meth:`.Session.begin` method
can be called while an existing :class:`.SessionTransaction` is already
present, producing a new :class:`.SessionTransaction` that temporarily
replaces the parent :class:`.SessionTransaction`. When a
:class:`.SessionTransaction` is produced as nested, it assigns itself to
the :attr:`.Session.transaction` attribute, and it additionally will assign
the previous :class:`.SessionTransaction` to its :attr:`.Session.parent`
attribute. The behavior is effectively a
stack, where :attr:`.Session.transaction` refers to the current head of
the stack, and the :attr:`.SessionTransaction.parent` attribute allows
traversal up the stack until :attr:`.SessionTransaction.parent` is
``None``, indicating the top of the stack.
When the scope of :class:`.SessionTransaction` is ended via
:meth:`.Session.commit` or :meth:`.Session.rollback`, it restores its
parent :class:`.SessionTransaction` back onto the
:attr:`.Session.transaction` attribute.
The purpose of this stack is to allow nesting of
:meth:`.Session.rollback` or :meth:`.Session.commit` calls in context
with various flavors of :meth:`.Session.begin`. This nesting behavior
applies to when :meth:`.Session.begin_nested` is used to emit a
SAVEPOINT transaction, and is also used to produce a so-called
"subtransaction" which allows a block of code to use a
begin/rollback/commit sequence regardless of whether or not its enclosing
code block has begun a transaction. The :meth:`.flush` method, whether
called explicitly or via autoflush, is the primary consumer of the
"subtransaction" feature, in that it wishes to guarantee that it works
within in a transaction block regardless of whether or not the
:class:`.Session` is in transactional mode when the method is called.
Note that the flush process that occurs within the "autoflush" feature
as well as when the :meth:`.Session.flush` method is used **always**
creates a :class:`.SessionTransaction` object. This object is normally
a subtransaction, unless the :class:`.Session` is in autocommit mode
and no transaction exists at all, in which case it's the outermost
transaction. Any event-handling logic or other inspection logic
needs to take into account whether a :class:`.SessionTransaction`
is the outermost transaction, a subtransaction, or a "nested" / SAVEPOINT
transaction.
.. seealso::
:meth:`.Session.rollback`
:meth:`.Session.commit`
:meth:`.Session.begin`
:meth:`.Session.begin_nested`
:attr:`.Session.is_active`
:meth:`.SessionEvents.after_transaction_create`
:meth:`.SessionEvents.after_transaction_end`
:meth:`.SessionEvents.after_commit`
:meth:`.SessionEvents.after_rollback`
:meth:`.SessionEvents.after_soft_rollback`
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block. If non-``None``, then this is either a "subtransaction"
or a "nested" / SAVEPOINT transaction. If the
:attr:`.SessionTransaction.nested` attribute is ``True``, then
this is a SAVEPOINT, and if ``False``, indicates this a subtransaction.
.. versionadded:: 1.0.16 - use ._parent for previous versions
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expire_all�expunge� expunge_allrZ rL � is_modified�bulk_save_objects�bulk_insert_mappings�bulk_update_mappings�merger �refreshr� �scalar)z1.0a� The :paramref:`.Session.weak_identity_map` parameter as well as the strong-referencing identity map are deprecated, and will be removed in a future release. For the use case where objects present in a :class:`.Session` need to be automatically strong referenced, see the recipe at :ref:`session_referencing_behavior` for an event-based approach to maintaining strong identity references. )z0.7zxThe :paramref:`.Session._enable_transaction_accounting` parameter is deprecated and will be removed in a future release.)z0.7z�:class:`.SessionExtension` is deprecated in favor of the :class:`.SessionEvents` listener interface. The :paramref:`.Session.extension` parameter will be removed in a future release.)�weak_identity_mapr= � extensionNTFc
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< dS )a Construct a new Session.
See also the :class:`.sessionmaker` function which is used to
generate a :class:`.Session`-producing callable with a given
set of arguments.
:param autocommit:
.. warning::
The autocommit flag is **not for general use**, and if it is
used, queries should only be invoked within the span of a
:meth:`.Session.begin` / :meth:`.Session.commit` pair. Executing
queries outside of a demarcated transaction is a legacy mode
of usage, and can in some cases lead to concurrent connection
checkouts.
Defaults to ``False``. When ``True``, the
:class:`.Session` does not keep a persistent transaction running,
and will acquire connections from the engine on an as-needed basis,
returning them immediately after their use. Flushes will begin and
commit (or possibly rollback) their own transaction if no
transaction is present. When using this mode, the
:meth:`.Session.begin` method is used to explicitly start
transactions.
.. seealso::
:ref:`session_autocommit`
:param autoflush: When ``True``, all query operations will issue a
:meth:`~.Session.flush` call to this ``Session`` before proceeding.
This is a convenience feature so that :meth:`~.Session.flush` need
not be called repeatedly in order for database queries to retrieve
results. It's typical that ``autoflush`` is used in conjunction
with ``autocommit=False``. In this scenario, explicit calls to
:meth:`~.Session.flush` are rarely needed; you usually only need to
call :meth:`~.Session.commit` (which flushes) to finalize changes.
:param bind: An optional :class:`.Engine` or :class:`.Connection` to
which this ``Session`` should be bound. When specified, all SQL
operations performed by this session will execute via this
connectable.
:param binds: A dictionary which may specify any number of
:class:`.Engine` or :class:`.Connection` objects as the source of
connectivity for SQL operations on a per-entity basis. The keys
of the dictionary consist of any series of mapped classes,
arbitrary Python classes that are bases for mapped classes,
:class:`.Table` objects and :class:`.Mapper` objects. The
values of the dictionary are then instances of :class:`.Engine`
or less commonly :class:`.Connection` objects. Operations which
proceed relative to a particular mapped class will consult this
dictionary for the closest matching entity in order to determine
which :class:`.Engine` should be used for a particular SQL
operation. The complete heuristics for resolution are
described at :meth:`.Session.get_bind`. Usage looks like::
Session = sessionmaker(binds={
SomeMappedClass: create_engine('postgresql://engine1'),
SomeDeclarativeBase: create_engine('postgresql://engine2'),
some_mapper: create_engine('postgresql://engine3'),
some_table: create_engine('postgresql://engine4'),
})
.. seealso::
:ref:`session_partitioning`
:meth:`.Session.bind_mapper`
:meth:`.Session.bind_table`
:meth:`.Session.get_bind`
:param \class_: Specify an alternate class other than
``sqlalchemy.orm.session.Session`` which should be used by the
returned class. This is the only argument that is local to the
:class:`.sessionmaker` function, and is not sent directly to the
constructor for ``Session``.
:param enable_baked_queries: defaults to ``True``. A flag consumed
by the :mod:`sqlalchemy.ext.baked` extension to determine if
"baked queries" should be cached, as is the normal operation
of this extension. When set to ``False``, all caching is disabled,
including baked queries defined by the calling application as
well as those used internally. Setting this flag to ``False``
can significantly reduce memory use, however will also degrade
performance for those areas that make use of baked queries
(such as relationship loaders). Additionally, baked query
logic in the calling application or potentially within the ORM
that may be malfunctioning due to cache key collisions or similar
can be flagged by observing if this flag resolves the issue.
.. versionadded:: 1.2
:param _enable_transaction_accounting: A
legacy-only flag which when ``False`` disables *all* 0.5-style
object accounting on transaction boundaries.
:param expire_on_commit: Defaults to ``True``. When ``True``, all
instances will be fully expired after each :meth:`~.commit`,
so that all attribute/object access subsequent to a completed
transaction will load from the most recent database state.
:param extension: An optional
:class:`~.SessionExtension` instance, or a list
of such instances, which will receive pre- and post- commit and
flush events, as well as a post-rollback event.
:param info: optional dictionary of arbitrary data to be associated
with this :class:`.Session`. Is available via the
:attr:`.Session.info` attribute. Note the dictionary is copied at
construction time so that modifications to the per-
:class:`.Session` dictionary will be local to that
:class:`.Session`.
.. versionadded:: 0.9.0
:param query_cls: Class which should be used to create new Query
objects, as returned by the :meth:`~.Session.query` method.
Defaults to :class:`.Query`.
:param twophase: When ``True``, all transactions will be started as
a "two phase" transaction, i.e. using the "two phase" semantics
of the database in use along with an XID. During a
:meth:`~.commit`, after :meth:`~.flush` has been issued for all
attached databases, the :meth:`~.TwoPhaseTransaction.prepare`
method on each database's :class:`.TwoPhaseTransaction` will be
called. This allows each database to roll back the entire
transaction, before each transaction is committed.
:param weak_identity_map: Defaults to ``True`` - when set to
``False``, objects placed in the :class:`.Session` will be
strongly referenced until explicitly removed or the
:class:`.Session` is closed.
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independently of all other :class:`.Session` objects.
.. versionadded:: 0.9.0
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.. warning::
The :meth:`.Session.begin` method is part of a larger pattern
of use with the :class:`.Session` known as **autocommit mode**.
This is essentially a **legacy mode of use** and is
not necessary for new applications. The :class:`.Session`
normally handles the work of "begin" transparently, which in
turn relies upon the Python DBAPI to transparently "begin"
transactions; there is **no need to explicitly begin transactions**
when using modern :class:`.Session` programming patterns.
In its default mode of ``autocommit=False``, the
:class:`.Session` does all of its work within
the context of a transaction, so as soon as you call
:meth:`.Session.commit`, the next transaction is implicitly
started when the next database operation is invoked. See
:ref:`session_autocommit` for further background.
The method will raise an error if this :class:`.Session` is already
inside of a transaction, unless
:paramref:`~.Session.begin.subtransactions` or
:paramref:`~.Session.begin.nested` are specified. A "subtransaction"
is essentially a code embedding pattern that does not affect the
transactional state of the database connection unless a rollback is
emitted, in which case the whole transaction is rolled back. For
documentation on subtransactions, please see
:ref:`session_subtransactions`.
:param subtransactions: if True, indicates that this
:meth:`~.Session.begin` can create a "subtransaction".
:param nested: if True, begins a SAVEPOINT transaction and is
equivalent to calling :meth:`~.Session.begin_nested`. For
documentation on SAVEPOINT transactions, please see
:ref:`session_begin_nested`.
:return: the :class:`.SessionTransaction` object. Note that
:class:`.SessionTransaction`
acts as a Python context manager, allowing :meth:`.Session.begin`
to be used in a "with" block. See :ref:`session_autocommit` for
an example.
.. seealso::
:ref:`session_autocommit`
:meth:`.Session.begin_nested`
N)r9 zSA transaction is already begun. Use subtransactions=True to allow subtransactions.)r� rQ r; r< r )r@ �subtransactionsr9 r r r r~ t s 4
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Session.beginc C s | j dd�S )a" Begin a "nested" transaction on this Session, e.g. SAVEPOINT.
The target database(s) and associated drivers must support SQL
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For documentation on SAVEPOINT
transactions, please see :ref:`session_begin_nested`.
:return: the :class:`.SessionTransaction` object. Note that
:class:`.SessionTransaction` acts as a context manager, allowing
:meth:`.Session.begin_nested` to be used in a "with" block.
See :ref:`session_begin_nested` for a usage example.
.. seealso::
:ref:`session_begin_nested`
:ref:`pysqlite_serializable` - special workarounds required
with the SQLite driver in order for SAVEPOINT to work
correctly.
T)r9 )r~ )r@ r r r r} � s zSession.begin_nestedc C s | j dkr n
| j �� dS )a� Rollback the current transaction in progress.
If no transaction is in progress, this method is a pass-through.
This method rolls back the current transaction or nested transaction
regardless of subtransactions being in effect. All subtransactions up
to the first real transaction are closed. Subtransactions occur when
:meth:`.begin` is called multiple times.
.. seealso::
:ref:`session_rollback`
N)r� r� )r@ r r r r� � s
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t�d��| j �� dS )a� Flush pending changes and commit the current transaction.
If no transaction is in progress, this method raises an
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By default, the :class:`.Session` also expires all database
loaded state on all ORM-managed attributes after transaction commit.
This so that subsequent operations load the most recent
data from the database. This behavior can be disabled using
the ``expire_on_commit=False`` option to :class:`.sessionmaker` or
the :class:`.Session` constructor.
If a subtransaction is in effect (which occurs when begin() is called
multiple times), the subtransaction will be closed, and the next call
to ``commit()`` will operate on the enclosing transaction.
When using the :class:`.Session` in its default mode of
``autocommit=False``, a new transaction will
be begun immediately after the commit, but note that the newly begun
transaction does *not* use any connection resources until the first
SQL is actually emitted.
.. seealso::
:ref:`session_committing`
NzNo transaction is begun.)r� r� r~ r; r< r� )r@ r r r r� � s
zSession.commitc C s2 | j dkr$| js| �� n
t�d��| j �� dS )ax Prepare the current transaction in progress for two phase commit.
If no transaction is in progress, this method raises an
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Only root transactions of two phase sessions can be prepared. If the
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NzNo transaction is begun.)r� r� r~ r; r< r� )r@ r r r r� s
zSession.preparec K s. |dkr | j |fd|i|��}| j|||d�S )a�
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either the :class:`.Connection` corresponding to the current
transaction is returned, or if no transaction is in progress, a new
one is begun and the :class:`.Connection` returned (note that no
transactional state is established with the DBAPI until the first
SQL statement is emitted).
Alternatively, if this :class:`.Session` is configured with
``autocommit=True``, an ad-hoc :class:`.Connection` is returned
using :meth:`.Engine.connect` on the underlying
:class:`.Engine`.
Ambiguity in multi-bind or unbound :class:`.Session` objects can be
resolved through any of the optional keyword arguments. This
ultimately makes usage of the :meth:`.get_bind` method for resolution.
:param bind:
Optional :class:`.Engine` to be used as the bind. If
this engine is already involved in an ongoing transaction,
that connection will be used. This argument takes precedence
over ``mapper``, ``clause``.
:param mapper:
Optional :func:`.mapper` mapped class, used to identify
the appropriate bind. This argument takes precedence over
``clause``.
:param clause:
A :class:`.ClauseElement` (i.e. :func:`~.sql.expression.select`,
:func:`~.sql.expression.text`,
etc.) which will be used to locate a bind, if a bind
cannot otherwise be identified.
:param close_with_result: Passed to :meth:`.Engine.connect`,
indicating the :class:`.Connection` should be considered
"single use", automatically closing when the first result set is
closed. This flag only has an effect if this :class:`.Session` is
configured with ``autocommit=True`` and does not already have a
transaction in progress.
:param execution_options: a dictionary of execution options that will
be passed to :meth:`.Connection.execution_options`, **when the
connection is first procured only**. If the connection is already
present within the :class:`.Session`, a warning is emitted and
the arguments are ignored.
.. versionadded:: 0.9.9
.. seealso::
:ref:`session_transaction_isolation`
:param \**kw:
Additional keyword arguments are sent to :meth:`get_bind()`,
allowing additional arguments to be passed to custom
implementations of :meth:`get_bind`.
N�clause)�close_with_resultrN )rL rM )r@ �mapperr� rO r� rN �kwr r r rP s FzSession.connectionc K s< | j d k r| j �||�S |jf |�}|r4|jf |�}|S d S )N)r� rM r{ rN )r@ r rN r� r r r r rM g s
z Session._connection_for_bindc K sF t j|dd�}|dkr,| j|fd|i|��}| j|dd��||pBi �S )a Execute a SQL expression construct or string statement within
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E.g.::
result = session.execute(
user_table.select().where(user_table.c.id == 5)
)
:meth:`~.Session.execute` accepts any executable clause construct,
such as :func:`~.sql.expression.select`,
:func:`~.sql.expression.insert`,
:func:`~.sql.expression.update`,
:func:`~.sql.expression.delete`, and
:func:`~.sql.expression.text`. Plain SQL strings can be passed
as well, which in the case of :meth:`.Session.execute` only
will be interpreted the same as if it were passed via a
:func:`~.expression.text` construct. That is, the following usage::
result = session.execute(
"SELECT * FROM user WHERE id=:param",
{"param":5}
)
is equivalent to::
from sqlalchemy import text
result = session.execute(
text("SELECT * FROM user WHERE id=:param"),
{"param":5}
)
The second positional argument to :meth:`.Session.execute` is an
optional parameter set. Similar to that of
:meth:`.Connection.execute`, whether this is passed as a single
dictionary, or a list of dictionaries, determines whether the DBAPI
cursor's ``execute()`` or ``executemany()`` is used to execute the
statement. An INSERT construct may be invoked for a single row::
result = session.execute(
users.insert(), {"id": 7, "name": "somename"})
or for multiple rows::
result = session.execute(users.insert(), [
{"id": 7, "name": "somename7"},
{"id": 8, "name": "somename8"},
{"id": 9, "name": "somename9"}
])
The statement is executed within the current transactional context of
this :class:`.Session`. The :class:`.Connection` which is used
to execute the statement can also be acquired directly by
calling the :meth:`.Session.connection` method. Both methods use
a rule-based resolution scheme in order to determine the
:class:`.Connection`, which in the average case is derived directly
from the "bind" of the :class:`.Session` itself, and in other cases
can be based on the :func:`.mapper`
and :class:`.Table` objects passed to the method; see the
documentation for :meth:`.Session.get_bind` for a full description of
this scheme.
The :meth:`.Session.execute` method does *not* invoke autoflush.
The :class:`.ResultProxy` returned by the :meth:`.Session.execute`
method is returned with the "close_with_result" flag set to true;
the significance of this flag is that if this :class:`.Session` is
autocommitting and does not have a transaction-dedicated
:class:`.Connection` available, a temporary :class:`.Connection` is
established for the statement execution, which is closed (meaning,
returned to the connection pool) when the :class:`.ResultProxy` has
consumed all available data. This applies *only* when the
:class:`.Session` is configured with autocommit=True and no
transaction has been started.
:param clause:
An executable statement (i.e. an :class:`.Executable` expression
such as :func:`.expression.select`) or string SQL statement
to be executed.
:param params:
Optional dictionary, or list of dictionaries, containing
bound parameter values. If a single dictionary, single-row
execution occurs; if a list of dictionaries, an
"executemany" will be invoked. The keys in each dictionary
must correspond to parameter names present in the statement.
:param mapper:
Optional :func:`.mapper` or mapped class, used to identify
the appropriate bind. This argument takes precedence over
``clause`` when locating a bind. See :meth:`.Session.get_bind`
for more details.
:param bind:
Optional :class:`.Engine` to be used as the bind. If
this engine is already involved in an ongoing transaction,
that connection will be used. This argument takes
precedence over ``mapper`` and ``clause`` when locating
a bind.
:param \**kw:
Additional keyword arguments are sent to :meth:`.Session.get_bind()`
to allow extensibility of "bind" schemes.
.. seealso::
:ref:`sqlexpression_toplevel` - Tutorial on using Core SQL
constructs.
:ref:`connections_toplevel` - Further information on direct
statement execution.
:meth:`.Connection.execute` - core level statement execution
method, which is :meth:`.Session.execute` ultimately uses
in order to execute the statement.
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no longer safe to be used.
E.g.::
try:
sess = Session()
sess.add(User())
sess.commit()
except gevent.Timeout:
sess.invalidate()
raise
except:
sess.rollback()
raise
This clears all items and ends any transaction in progress.
If this session were created with ``autocommit=False``, a new
transaction is immediately begun. Note that this new transaction does
not use any connection resources until they are first needed.
.. versionadded:: 0.9.9
T)r� N)r� )r@ r r r r� s zSession.invalidatec C s4 | � � | jd k r0x | j�� D ]}|�|� q W d S )N)r� r� rT r� )r@ r� r� r r r r� , s
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rF t|t�s8t�d| ��n
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:param mapper: a :class:`.Mapper` object, or an instance of a mapped
class, or any Python class that is the base of a set of mapped
classes.
:param bind: an :class:`.Engine` or :class:`.Connection` object.
.. seealso::
:ref:`session_partitioning`
:paramref:`.Session.binds`
:meth:`.Session.bind_table`
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:meth:`.Session.get_bind` method.
:param table: a :class:`.Table` object, which is typically the target
of an ORM mapping, or is present within a selectable that is
mapped.
:param bind: an :class:`.Engine` or :class:`.Connection` object.
.. seealso::
:ref:`session_partitioning`
:paramref:`.Session.binds`
:meth:`.Session.bind_mapper`
N)r� )r@ �tablerO r r r �
bind_tablep s zSession.bind_tablec C sn || krdkr.n n| j r$| j S t�d��|dk rry t|�}W n. tjk
rp t|t�rjt�|��n� Y nX | j r�|r�x$|j
j D ]}|| j kr�| j | S q�W |dkr�|j }|dk r�x*t
j|dd�D ]}|| j kr�| j | S q�W | j r�| j S t|tjj��r|j �r|j S |�r&|j j �r&|j j S g }|dk �rB|�d| � |dk �rV|�d� t�dd�|� ��dS ) a� Return a "bind" to which this :class:`.Session` is bound.
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appropriate bind to return.
Note that the "mapper" argument is usually present
when :meth:`.Session.get_bind` is called via an ORM
operation such as a :meth:`.Session.query`, each
individual INSERT/UPDATE/DELETE operation within a
:meth:`.Session.flush`, call, etc.
The order of resolution is:
1. if mapper given and session.binds is present,
locate a bind based first on the mapper in use, then
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present in the ``__mro__`` of the mapped class, from more specific
superclasses to more general.
2. if clause given and session.binds is present,
locate a bind based on :class:`.Table` objects
found in the given clause present in session.binds.
3. if session.bind is present, return that.
4. if clause given, attempt to return a bind
linked to the :class:`.MetaData` ultimately
associated with the clause.
5. if mapper given, attempt to return a bind
linked to the :class:`.MetaData` ultimately
associated with the :class:`.Table` or other
selectable to which the mapper is mapped.
6. No bind can be found, :exc:`~sqlalchemy.exc.UnboundExecutionError`
is raised.
Note that the :meth:`.Session.get_bind` method can be overridden on
a user-defined subclass of :class:`.Session` to provide any kind
of bind resolution scheme. See the example at
:ref:`session_custom_partitioning`.
:param mapper:
Optional :func:`.mapper` mapped class or instance of
:class:`.Mapper`. The bind can be derived from a :class:`.Mapper`
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:class:`.Session`, and secondly by consulting the :class:`.MetaData`
associated with the :class:`.Table` to which the :class:`.Mapper`
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:param clause:
A :class:`.ClauseElement` (i.e. :func:`~.sql.expression.select`,
:func:`~.sql.expression.text`,
etc.). If the ``mapper`` argument is not present or could not
produce a bind, the given expression construct will be searched
for a bound element, typically a :class:`.Table` associated with
bound :class:`.MetaData`.
.. seealso::
:ref:`session_partitioning`
:paramref:`.Session.binds`
:meth:`.Session.bind_mapper`
:meth:`.Session.bind_table`
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|��|j|||d�dkr�t�dt|� ��dS )a9 Expire and refresh the attributes on the given instance.
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the lazy load of that attribute.
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single refresh operation.
Note that a highly isolated transaction will return the same values as
were previously read in that same transaction, regardless of changes
in database state outside of that transaction - usage of
:meth:`~Session.refresh` usually only makes sense if non-ORM SQL
statement were emitted in the ongoing transaction, or if autocommit
mode is turned on.
:param attribute_names: optional. An iterable collection of
string attribute names indicating a subset of attributes to
be refreshed.
:param with_for_update: optional boolean ``True`` indicating FOR UPDATE
should be used, or may be a dictionary containing flags to
indicate a more specific set of FOR UPDATE flags for the SELECT;
flags should match the parameters of :meth:`.Query.with_for_update`.
Supersedes the :paramref:`.Session.refresh.lockmode` parameter.
.. versionadded:: 1.2
:param lockmode: Passed to the :class:`~sqlalchemy.orm.query.Query`
as used by :meth:`~sqlalchemy.orm.query.Query.with_lockmode`.
Superseded by :paramref:`.Session.refresh.with_for_update`.
.. seealso::
:ref:`session_expire` - introductory material
:meth:`.Session.expire`
:meth:`.Session.expire_all`
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load all expired attributes for the given instance. Note that
a highly isolated transaction will return the same values as were
previously read in that same transaction, regardless of changes
in database state outside of that transaction.
To expire individual objects and individual attributes
on those objects, use :meth:`Session.expire`.
The :class:`.Session` object's default behavior is to
expire all state whenever the :meth:`Session.rollback`
or :meth:`Session.commit` methods are called, so that new
state can be loaded for the new transaction. For this reason,
calling :meth:`Session.expire_all` should not be needed when
autocommit is ``False``, assuming the transaction is isolated.
.. seealso::
:ref:`session_expire` - introductory material
:meth:`.Session.expire`
:meth:`.Session.refresh`
N)rd ri rk rl rm )r@ r r r r r� � s zSession.expire_allc C s@ yt �|�}W n tjk
r. t�|��Y nX | �||� dS )a� Expire the attributes on an instance.
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load all expired attributes for the given instance. Note that
a highly isolated transaction will return the same values as were
previously read in that same transaction, regardless of changes
in database state outside of that transaction.
To expire all objects in the :class:`.Session` simultaneously,
use :meth:`Session.expire_all`.
The :class:`.Session` object's default behavior is to
expire all state whenever the :meth:`Session.rollback`
or :meth:`Session.commit` methods are called, so that new
state can be loaded for the new transaction. For this reason,
calling :meth:`Session.expire` only makes sense for the specific
case that a non-ORM SQL statement was emitted in the current
transaction.
:param instance: The instance to be refreshed.
:param attribute_names: optional list of string attribute names
indicating a subset of attributes to be expired.
.. seealso::
:ref:`session_expire` - introductory material
:meth:`.Session.expire`
:meth:`.Session.refresh`
N)r r� r r� r� r� )r@ r* r� r r r r r� � s
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to load the object from the database based on primary key, and if
none can be located, creates a new instance. The state of each
attribute on the source instance is then copied to the target
instance. The resulting target instance is then returned by the
method; the original source instance is left unmodified, and
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This operation cascades to associated instances if the association is
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See :ref:`unitofwork_merging` for a detailed discussion of merging.
.. versionchanged:: 1.1 - :meth:`.Session.merge` will now reconcile
pending objects with overlapping primary keys in the same way
as persistent. See :ref:`change_3601` for discussion.
:param instance: Instance to be merged.
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events as well as all database access. This flag is used for
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from a second level cache, or to transfer just-loaded objects
into the :class:`.Session` owned by a worker thread or process
without re-querying the database.
The ``load=False`` use case adds the caveat that the given
object has to be in a "clean" state, that is, has no pending changes
to be flushed - even if the incoming object is detached from any
:class:`.Session`. This is so that when
the merge operation populates local attributes and
cascades to related objects and
collections, the values can be "stamped" onto the
target object as is, without generating any history or attribute
events, and without the need to reconcile the incoming data with
any existing related objects or collections that might not
be loaded. The resulting objects from ``load=False`` are always
produced as "clean", so it is only appropriate that the given objects
should be "clean" as well, else this suggests a mis-use of the
method.
.. seealso::
:func:`.make_transient_to_detached` - provides for an alternative
means of "merging" a single object into the :class:`.Session`
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.. warning::
:meth:`.enable_relationship_loading` exists to serve special
use cases and is not recommended for general use.
Accesses of attributes mapped with :func:`.relationship`
will attempt to load a value from the database using this
:class:`.Session` as the source of connectivity. The values
will be loaded based on foreign key and primary key values
present on this object - if not present, then those relationships
will be unavailable.
The object will be attached to this session, but will
**not** participate in any persistence operations; its state
for almost all purposes will remain either "transient" or
"detached", except for the case of relationship loading.
Also note that backrefs will often not work as expected.
Altering a relationship-bound attribute on the target object
may not fire off a backref event, if the effective value
is what was already loaded from a foreign-key-holding value.
The :meth:`.Session.enable_relationship_loading` method is
similar to the ``load_on_pending`` flag on :func:`.relationship`.
Unlike that flag, :meth:`.Session.enable_relationship_loading` allows
an object to remain transient while still being able to load
related items.
To make a transient object associated with a :class:`.Session`
via :meth:`.Session.enable_relationship_loading` pending, add
it to the :class:`.Session` using :meth:`.Session.add` normally.
If the object instead represents an existing identity in the database,
it should be merged using :meth:`.Session.merge`.
:meth:`.Session.enable_relationship_loading` does not improve
behavior when the ORM is used normally - object references should be
constructed at the object level, not at the foreign key level, so
that they are present in an ordinary way before flush()
proceeds. This method is not intended for general use.
.. seealso::
``load_on_pending`` at :func:`.relationship` - this flag
allows per-relationship loading of many-to-ones on items that
are pending.
:func:`.make_transient_to_detached` - allows for an object to
be added to a :class:`.Session` without SQL emitted, which then
will unexpire attributes on access.
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context and do not affect the state of the transaction, unless an
error occurs, in which case the entire transaction is rolled back.
You may flush() as often as you like within a transaction to move
changes from Python to the database's transaction buffer.
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C sb dd� }t dd� |D ��}|s*t||d�}x2t�||�D ]"\\}}} | �|| |d||d� q8W dS ) a� Perform a bulk save of the given list of objects.
The bulk save feature allows mapped objects to be used as the
source of simple INSERT and UPDATE operations which can be more easily
grouped together into higher performing "executemany"
operations; the extraction of data from the objects is also performed
using a lower-latency process that ignores whether or not attributes
have actually been modified in the case of UPDATEs, and also ignores
SQL expressions.
The objects as given are not added to the session and no additional
state is established on them, unless the ``return_defaults`` flag
is also set, in which case primary key attributes and server-side
default values will be populated.
.. versionadded:: 1.0.0
.. warning::
The bulk save feature allows for a lower-latency INSERT/UPDATE
of rows at the expense of most other unit-of-work features.
Features such as object management, relationship handling,
and SQL clause support are **silently omitted** in favor of raw
INSERT/UPDATES of records.
**Please read the list of caveats at** :ref:`bulk_operations`
**before using this method, and fully test and confirm the
functionality of all code developed using these systems.**
:param objects: a list of mapped object instances. The mapped
objects are persisted as is, and are **not** associated with the
:class:`.Session` afterwards.
For each object, whether the object is sent as an INSERT or an
UPDATE is dependent on the same rules used by the :class:`.Session`
in traditional operation; if the object has the
:attr:`.InstanceState.key`
attribute set, then the object is assumed to be "detached" and
will result in an UPDATE. Otherwise, an INSERT is used.
In the case of an UPDATE, statements are grouped based on which
attributes have changed, and are thus to be the subject of each
SET clause. If ``update_changed_only`` is False, then all
attributes present within each object are applied to the UPDATE
statement, which may help in allowing the statements to be grouped
together into a larger executemany(), and will also reduce the
overhead of checking history on attributes.
:param return_defaults: when True, rows that are missing values which
generate defaults, namely integer primary key defaults and sequences,
will be inserted **one at a time**, so that the primary key value
is available. In particular this will allow joined-inheritance
and other multi-table mappings to insert correctly without the need
to provide primary key values ahead of time; however,
:paramref:`.Session.bulk_save_objects.return_defaults` **greatly
reduces the performance gains** of the method overall.
:param update_changed_only: when True, UPDATE statements are rendered
based on those attributes in each state that have logged changes.
When False, all attributes present are rendered into the SET clause
with the exception of primary key attributes.
:param preserve_order: when True, the order of inserts and updates
matches exactly the order in which the objects are given. When
False, common types of objects are grouped into inserts
and updates, to allow for more batching opportunities.
.. versionadded:: 1.3
.. seealso::
:ref:`bulk_operations`
:meth:`.Session.bulk_insert_mappings`
:meth:`.Session.bulk_update_mappings`
c S s | j | jd k fS )N)r� rf )r r r r rf }
s z&Session.bulk_save_objects.<locals>.keyc s s | ]}t �|�V qd S )N)r r� )r� r� r r r r� �
s z,Session.bulk_save_objects.<locals>.<genexpr>)rf TFN)�tuple�sorted� itertools�groupby�_bulk_save_mappings)
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s V zSession.bulk_save_objectsc C s | � ||dd|d|� dS )a Perform a bulk insert of the given list of mapping dictionaries.
The bulk insert feature allows plain Python dictionaries to be used as
the source of simple INSERT operations which can be more easily
grouped together into higher performing "executemany"
operations. Using dictionaries, there is no "history" or session
state management features in use, reducing latency when inserting
large numbers of simple rows.
The values within the dictionaries as given are typically passed
without modification into Core :meth:`.Insert` constructs, after
organizing the values within them across the tables to which
the given mapper is mapped.
.. versionadded:: 1.0.0
.. warning::
The bulk insert feature allows for a lower-latency INSERT
of rows at the expense of most other unit-of-work features.
Features such as object management, relationship handling,
and SQL clause support are **silently omitted** in favor of raw
INSERT of records.
**Please read the list of caveats at** :ref:`bulk_operations`
**before using this method, and fully test and confirm the
functionality of all code developed using these systems.**
:param mapper: a mapped class, or the actual :class:`.Mapper` object,
representing the single kind of object represented within the mapping
list.
:param mappings: a list of dictionaries, each one containing the state
of the mapped row to be inserted, in terms of the attribute names
on the mapped class. If the mapping refers to multiple tables,
such as a joined-inheritance mapping, each dictionary must contain
all keys to be populated into all tables.
:param return_defaults: when True, rows that are missing values which
generate defaults, namely integer primary key defaults and sequences,
will be inserted **one at a time**, so that the primary key value
is available. In particular this will allow joined-inheritance
and other multi-table mappings to insert correctly without the need
to provide primary
key values ahead of time; however,
:paramref:`.Session.bulk_insert_mappings.return_defaults`
**greatly reduces the performance gains** of the method overall.
If the rows
to be inserted only refer to a single table, then there is no
reason this flag should be set as the returned default information
is not used.
:param render_nulls: When True, a value of ``None`` will result
in a NULL value being included in the INSERT statement, rather
than the column being omitted from the INSERT. This allows all
the rows being INSERTed to have the identical set of columns which
allows the full set of rows to be batched to the DBAPI. Normally,
each column-set that contains a different combination of NULL values
than the previous row must omit a different series of columns from
the rendered INSERT statement, which means it must be emitted as a
separate statement. By passing this flag, the full set of rows
are guaranteed to be batchable into one batch; the cost however is
that server-side defaults which are invoked by an omitted column will
be skipped, so care must be taken to ensure that these are not
necessary.
.. warning::
When this flag is set, **server side default SQL values will
not be invoked** for those columns that are inserted as NULL;
the NULL value will be sent explicitly. Care must be taken
to ensure that no server-side default functions need to be
invoked for the operation as a whole.
.. versionadded:: 1.1
.. seealso::
:ref:`bulk_operations`
:meth:`.Session.bulk_save_objects`
:meth:`.Session.bulk_update_mappings`
FN)r )r@ r� �mappingsr � render_nullsr r r r� �
s Xz Session.bulk_insert_mappingsc C s | � ||ddddd� dS )a� Perform a bulk update of the given list of mapping dictionaries.
The bulk update feature allows plain Python dictionaries to be used as
the source of simple UPDATE operations which can be more easily
grouped together into higher performing "executemany"
operations. Using dictionaries, there is no "history" or session
state management features in use, reducing latency when updating
large numbers of simple rows.
.. versionadded:: 1.0.0
.. warning::
The bulk update feature allows for a lower-latency UPDATE
of rows at the expense of most other unit-of-work features.
Features such as object management, relationship handling,
and SQL clause support are **silently omitted** in favor of raw
UPDATES of records.
**Please read the list of caveats at** :ref:`bulk_operations`
**before using this method, and fully test and confirm the
functionality of all code developed using these systems.**
:param mapper: a mapped class, or the actual :class:`.Mapper` object,
representing the single kind of object represented within the mapping
list.
:param mappings: a list of dictionaries, each one containing the state
of the mapped row to be updated, in terms of the attribute names
on the mapped class. If the mapping refers to multiple tables,
such as a joined-inheritance mapping, each dictionary may contain
keys corresponding to all tables. All those keys which are present
and are not part of the primary key are applied to the SET clause
of the UPDATE statement; the primary key values, which are required,
are applied to the WHERE clause.
.. seealso::
:ref:`bulk_operations`
:meth:`.Session.bulk_insert_mappings`
:meth:`.Session.bulk_save_objects`
TFN)r )r@ r� r r r r r� �
s /z Session.bulk_update_mappingsc C s� t |�}d| _| jdd�}zjy8|r6t�|||||� nt�||||||� |�� W n, t�� � |j dd� W d Q R X Y nX W d d| _X d S )NT)r� )r� F)
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zSession._bulk_save_mappings)z0.8z�The :paramref:`.Session.is_modified.passive` flag is deprecated and will be removed in a future release. The flag is no longer used and is ignored.)r c
C sv t |�}|jsdS |j}xX|jjD ]H}|s6t|jd�s"t|jd�sDq"|jj||tjd�\}}} |sf| r"dS q"W dS dS )aZ
Return ``True`` if the given instance has locally
modified attributes.
This method retrieves the history for each instrumented
attribute on the instance and performs a comparison of the current
value to its previously committed value, if any.
It is in effect a more expensive and accurate
version of checking for the given instance in the
:attr:`.Session.dirty` collection; a full test for
each attribute's net "dirty" status is performed.
E.g.::
return session.is_modified(someobject)
A few caveats to this method apply:
* Instances present in the :attr:`.Session.dirty` collection may
report ``False`` when tested with this method. This is because
the object may have received change events via attribute mutation,
thus placing it in :attr:`.Session.dirty`, but ultimately the state
is the same as that loaded from the database, resulting in no net
change here.
* Scalar attributes may not have recorded the previously set
value when a new value was applied, if the attribute was not loaded,
or was expired, at the time the new value was received - in these
cases, the attribute is assumed to have a change, even if there is
ultimately no net change against its database value. SQLAlchemy in
most cases does not need the "old" value when a set event occurs, so
it skips the expense of a SQL call if the old value isn't present,
based on the assumption that an UPDATE of the scalar value is
usually needed, and in those few cases where it isn't, is less
expensive on average than issuing a defensive SELECT.
The "old" value is fetched unconditionally upon set only if the
attribute container has the ``active_history`` flag set to ``True``.
This flag is set typically for primary key attributes and scalar
object references that are not a simple many-to-one. To set this
flag for any arbitrary mapped column, use the ``active_history``
argument with :func:`.column_property`.
:param instance: mapped instance to be tested for pending changes.
:param include_collections: Indicates if multivalued collections
should be included in the operation. Setting this to ``False`` is a
way to detect only local-column based properties (i.e. scalar columns
or many-to-one foreign keys) that would result in an UPDATE for this
instance upon flush.
:param passive: not used
FZget_collection� get_history)r TN) r rj rl r� r �hasattr�implr Z NO_CHANGE)
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The :class:`.Session` in its default mode of ``autocommit=False``
is essentially always in "transaction mode", in that a
:class:`.SessionTransaction` is associated with it as soon as
it is instantiated. This :class:`.SessionTransaction` is immediately
replaced with a new one as soon as it is ended, due to a rollback,
commit, or close operation.
"Transaction mode" does *not* indicate whether
or not actual database connection resources are in use; the
:class:`.SessionTransaction` object coordinates among zero or more
actual database transactions, and starts out with none, accumulating
individual DBAPI connections as different data sources are used
within its scope. The best way to track when a particular
:class:`.Session` has actually begun to use DBAPI resources is to
implement a listener using the :meth:`.SessionEvents.after_begin`
method, which will deliver both the :class:`.Session` as well as the
target :class:`.Connection` to a user-defined event listener.
The "partial rollback" state refers to when an "inner" transaction,
typically used during a flush, encounters an error and emits a
rollback of the DBAPI connection. At this point, the
:class:`.Session` is in "partial rollback" and awaits for the user to
call :meth:`.Session.rollback`, in order to close out the
transaction stack. It is in this "partial rollback" period that the
:attr:`.is_active` flag returns False. After the call to
:meth:`.Session.rollback`, the :class:`.SessionTransaction` is
replaced with a new one and :attr:`.is_active` returns ``True`` again.
When a :class:`.Session` is used in ``autocommit=True`` mode, the
:class:`.SessionTransaction` is only instantiated within the scope
of a flush call, or when :meth:`.Session.begin` is called. So
:attr:`.is_active` will always be ``False`` outside of a flush or
:meth:`.Session.begin` block in this mode, and will be ``True``
within the :meth:`.Session.begin` block as long as it doesn't enter
"partial rollback" state.
From all the above, it follows that the only purpose to this flag is
for application frameworks that wish to detect is a "rollback" is
necessary within a generic error handling routine, for
:class:`.Session` objects that would otherwise be in
"partial rollback" mode. In a typical integration case, this is also
not necessary as it is standard practice to emit
:meth:`.Session.rollback` unconditionally within the outermost
exception catch.
To track the transactional state of a :class:`.Session` fully,
use event listeners, primarily the :meth:`.SessionEvents.after_begin`,
:meth:`.SessionEvents.after_commit`,
:meth:`.SessionEvents.after_rollback` and related events.
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E.g.::
some_mapped_object in session.dirty
Instances are considered dirty when they were modified but not
deleted.
Note that this 'dirty' calculation is 'optimistic'; most
attribute-setting or collection modification operations will
mark an instance as 'dirty' and place it in this set, even if
there is no net change to the attribute's value. At flush
time, the value of each attribute is compared to its
previously saved value, and if there's no net change, no SQL
operation will occur (this is a more expensive operation so
it's only done at flush time).
To check if an instance has actionable net changes to its
attributes, use the :meth:`.Session.is_modified` method.
c s g | ]}|� j kr|�� �qS r )rV r� )r� r )r@ r r r� s z!Session.dirty.<locals>.<listcomp>)r � IdentitySetr )r@ r )r@ r r
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r a' A configurable :class:`.Session` factory.
The :class:`.sessionmaker` factory generates new
:class:`.Session` objects when called, creating them given
the configurational arguments established here.
e.g.::
# global scope
Session = sessionmaker(autoflush=False)
# later, in a local scope, create and use a session:
sess = Session()
Any keyword arguments sent to the constructor itself will override the
"configured" keywords::
Session = sessionmaker()
# bind an individual session to a connection
sess = Session(bind=connection)
The class also includes a method :meth:`.configure`, which can
be used to specify additional keyword arguments to the factory, which
will take effect for subsequent :class:`.Session` objects generated.
This is usually used to associate one or more :class:`.Engine` objects
with an existing :class:`.sessionmaker` factory before it is first
used::
# application starts
Session = sessionmaker()
# ... later
engine = create_engine('sqlite:///foo.db')
Session.configure(bind=engine)
sess = Session()
.. seealso:
:ref:`session_getting` - introductory text on creating
sessions using :class:`.sessionmaker`.
NTFc K sL ||d< ||d< ||d< ||d< |dk r0||d< || _ t|j|fi �| _dS )a9 Construct a new :class:`.sessionmaker`.
All arguments here except for ``class_`` correspond to arguments
accepted by :class:`.Session` directly. See the
:meth:`.Session.__init__` docstring for more details on parameters.
:param bind: a :class:`.Engine` or other :class:`.Connectable` with
which newly created :class:`.Session` objects will be associated.
:param class\_: class to use in order to create new :class:`.Session`
objects. Defaults to :class:`.Session`.
:param autoflush: The autoflush setting to use with newly created
:class:`.Session` objects.
:param autocommit: The autocommit setting to use with newly created
:class:`.Session` objects.
:param expire_on_commit=True: the expire_on_commit setting to use
with newly created :class:`.Session` objects.
:param info: optional dictionary of information that will be available
via :attr:`.Session.info`. Note this dictionary is *updated*, not
replaced, when the ``info`` parameter is specified to the specific
:class:`.Session` construction operation.
.. versionadded:: 0.9.0
:param \**kw: all other keyword arguments are passed to the
constructor of newly created :class:`.Session` objects.
rO r� r� rq Nr� )r� r� r+ r� )r@ rO r� r� r� rq r� r� r r r rB L s %zsessionmaker.__init__c K s` xR| j �� D ]D\}}|dkrDd|krD|�� }|�|d � ||d< q |�||� q W | jf |�S )ae Produce a new :class:`.Session` object using the configuration
established in this :class:`.sessionmaker`.
In Python, the ``__call__`` method is invoked on an object when
it is "called" in the same way as a function::
Session = sessionmaker()
session = Session() # invokes sessionmaker.__call__()
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zsessionmaker.__call__c K s | j �|� dS )z�(Re)configure the arguments for this sessionmaker.
e.g.::
Session = sessionmaker()
Session.configure(bind=create_engine('sqlite://'))
N)r� rw )r@ Znew_kwr r r � configure� s zsessionmaker.configurec C s, d| j j| jjd�dd� | j�� D ��f S )Nz%s(class_=%r, %s)z, c s s | ]\}}d ||f V qdS )z%s=%rNr )r� r# r$ r r r r� � s z(sessionmaker.__repr__.<locals>.<genexpr>)� __class__r+ r� r� r� rc )r@ r r r �__repr__� s zsessionmaker.__repr__) r+ r, r- r. r rB r& r' r) r r r r r s , ) c C s xt �� D ] } | �� q
W dS )aO Close all sessions in memory.
This function consults a global registry of all :class:`.Session` objects
and calls :meth:`.Session.close` on them, which resets them to a clean
state.
This function is not for general use but may be useful for test suites
within the teardown scheme.
.. versionadded:: 1.3
N)r r� r� )r� r r r r# � s r# c C sN t �| �}t|�}|r"|�|g� |j�� |jr6|`|jr@|`|jrJ|`dS )aM Alter the state of the given instance so that it is :term:`transient`.
.. note::
:func:`.make_transient` is a special-case function for
advanced use cases only.
The given mapped instance is assumed to be in the :term:`persistent` or
:term:`detached` state. The function will remove its association with any
:class:`.Session` as well as its :attr:`.InstanceState.identity`. The
effect is that the object will behave as though it were newly constructed,
except retaining any attribute / collection values that were loaded at the
time of the call. The :attr:`.InstanceState.deleted` flag is also reset
if this object had been deleted as a result of using
:meth:`.Session.delete`.
.. warning::
:func:`.make_transient` does **not** "unexpire" or otherwise eagerly
load ORM-mapped attributes that are not currently loaded at the time
the function is called. This includes attributes which:
* were expired via :meth:`.Session.expire`
* were expired as the natural effect of committing a session
transaction, e.g. :meth:`.Session.commit`
* are normally :term:`lazy loaded` but are not currently loaded
* are "deferred" via :ref:`deferred` and are not yet loaded
* were not present in the query which loaded this object, such as that
which is common in joined table inheritance and other scenarios.
After :func:`.make_transient` is called, unloaded attributes such
as those above will normally resolve to the value ``None`` when
accessed, or an empty collection for a collection-oriented attribute.
As the object is transient and un-associated with any database
identity, it will no longer retrieve these values.
.. seealso::
:func:`.make_transient_to_detached`
N) r r� r! rb Zexpired_attributesrv Z callablesrf rV )r* r ro r r r �make_transient� s .
r* c C sX t �| �}|js|jr t�d��|j�|�|_|jr8|`|� |j
� |� |j
|j � dS )a� Make the given transient instance :term:`detached`.
.. note::
:func:`.make_transient_to_detached` is a special-case function for
advanced use cases only.
All attribute history on the given instance
will be reset as though the instance were freshly loaded
from a query. Missing attributes will be marked as expired.
The primary key attributes of the object, which are required, will be made
into the "key" of the instance.
The object can then be added to a session, or merged
possibly with the load=False flag, at which point it will look
as if it were loaded that way, without emitting SQL.
This is a special use case function that differs from a normal
call to :meth:`.Session.merge` in that a given persistent state
can be manufactured without any SQL calls.
.. versionadded:: 0.9.5
.. seealso::
:func:`.make_transient`
:meth:`.Session.enable_relationship_loading`
z Given object must be transientN)
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r. t�| ��Y n
X t|�S dS )z�Return the :class:`.Session` to which the given instance belongs.
This is essentially the same as the :attr:`.InstanceState.session`
accessor. See that attribute for details.
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