text: # orm/deprecated_interfaces.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 .interfaces import EXT_CONTINUE
  from .. import event
  from .. import util
  
  
  @util.langhelpers.dependency_for("sqlalchemy.orm.interfaces")
  class MapperExtension(object):
      """Base implementation for :class:`.Mapper` event hooks.
  
      .. deprecated:: 0.7
  
         :class:`.MapperExtension` is deprecated and will be removed in a future
         release.  Please refer to :func:`.event.listen` in conjunction with
         the :class:`.MapperEvents` listener interface.
  
      New extension classes subclass :class:`.MapperExtension` and are specified
      using the ``extension`` mapper() argument, which is a single
      :class:`.MapperExtension` or a list of such::
  
          from sqlalchemy.orm.interfaces import MapperExtension
  
          class MyExtension(MapperExtension):
              def before_insert(self, mapper, connection, instance):
                  print "instance %s before insert !" % instance
  
          m = mapper(User, users_table, extension=MyExtension())
  
      A single mapper can maintain a chain of ``MapperExtension``
      objects. When a particular mapping event occurs, the
      corresponding method on each ``MapperExtension`` is invoked
      serially, and each method has the ability to halt the chain
      from proceeding further::
  
          m = mapper(User, users_table, extension=[ext1, ext2, ext3])
  
      Each ``MapperExtension`` method returns the symbol
      EXT_CONTINUE by default.   This symbol generally means "move
      to the next ``MapperExtension`` for processing".  For methods
      that return objects like translated rows or new object
      instances, EXT_CONTINUE means the result of the method
      should be ignored.   In some cases it's required for a
      default mapper activity to be performed, such as adding a
      new instance to a result list.
  
      The symbol EXT_STOP has significance within a chain
      of ``MapperExtension`` objects that the chain will be stopped
      when this symbol is returned.  Like EXT_CONTINUE, it also
      has additional significance in some cases that a default
      mapper activity will not be performed.
  
      """
  
      @classmethod
      def _adapt_instrument_class(cls, self, listener):
          cls._adapt_listener_methods(self, listener, ("instrument_class",))
  
      @classmethod
      def _adapt_listener(cls, self, listener):
          cls._adapt_listener_methods(
              self,
              listener,
              (
                  "init_instance",
                  "init_failed",
                  "reconstruct_instance",
                  "before_insert",
                  "after_insert",
                  "before_update",
                  "after_update",
                  "before_delete",
                  "after_delete",
              ),
          )
  
      @classmethod
      def _adapt_listener_methods(cls, self, listener, methods):
  
          for meth in methods:
              me_meth = getattr(MapperExtension, meth)
              ls_meth = getattr(listener, meth)
  
              if not util.methods_equivalent(me_meth, ls_meth):
                  util.warn_deprecated(
                      "MapperExtension.%s is deprecated.  The "
                      "MapperExtension class will be removed in a future "
                      "release.  Please transition to the @event interface, "
                      "using @event.listens_for(mapped_class, '%s')."
                      % (meth, meth)
                  )
  
                  if meth == "reconstruct_instance":
  
                      def go(ls_meth):
                          def reconstruct(instance, ctx):
                              ls_meth(self, instance)
  
                          return reconstruct
  
                      event.listen(
                          self.class_manager,
                          "load",
                          go(ls_meth),
                          raw=False,
                          propagate=True,
                      )
                  elif meth == "init_instance":
  
                      def go(ls_meth):
                          def init_instance(instance, args, kwargs):
                              ls_meth(
                                  self,
                                  self.class_,
                                  self.class_manager.original_init,
                                  instance,
                                  args,
                                  kwargs,
                              )
  
                          return init_instance
  
                      event.listen(
                          self.class_manager,
                          "init",
                          go(ls_meth),
                          raw=False,
                          propagate=True,
                      )
                  elif meth == "init_failed":
  
                      def go(ls_meth):
                          def init_failed(instance, args, kwargs):
                              util.warn_exception(
                                  ls_meth,
                                  self,
                                  self.class_,
                                  self.class_manager.original_init,
                                  instance,
                                  args,
                                  kwargs,
                              )
  
                          return init_failed
  
                      event.listen(
                          self.class_manager,
                          "init_failure",
                          go(ls_meth),
                          raw=False,
                          propagate=True,
                      )
                  else:
                      event.listen(
                          self,
                          "%s" % meth,
                          ls_meth,
                          raw=False,
                          retval=True,
                          propagate=True,
                      )
  
      def instrument_class(self, mapper, class_):
          """Receive a class when the mapper is first constructed, and has
          applied instrumentation to the mapped class.
  
          The return value is only significant within the ``MapperExtension``
          chain; the parent mapper's behavior isn't modified by this method.
  
          """
          return EXT_CONTINUE
  
      def init_instance(self, mapper, class_, oldinit, instance, args, kwargs):
          """Receive an instance when its constructor is called.
  
          This method is only called during a userland construction of
          an object.  It is not called when an object is loaded from the
          database.
  
          The return value is only significant within the ``MapperExtension``
          chain; the parent mapper's behavior isn't modified by this method.
  
          """
          return EXT_CONTINUE
  
      def init_failed(self, mapper, class_, oldinit, instance, args, kwargs):
          """Receive an instance when its constructor has been called,
          and raised an exception.
  
          This method is only called during a userland construction of
          an object.  It is not called when an object is loaded from the
          database.
  
          The return value is only significant within the ``MapperExtension``
          chain; the parent mapper's behavior isn't modified by this method.
  
          """
          return EXT_CONTINUE
  
      def reconstruct_instance(self, mapper, instance):
          """Receive an object instance after it has been created via
          ``__new__``, and after initial attribute population has
          occurred.
  
          This typically occurs when the instance is created based on
          incoming result rows, and is only called once for that
          instance's lifetime.
  
          Note that during a result-row load, this method is called upon
          the first row received for this instance.  Note that some
          attributes and collections may or may not be loaded or even
          initialized, depending on what's present in the result rows.
  
          The return value is only significant within the ``MapperExtension``
          chain; the parent mapper's behavior isn't modified by this method.
  
          """
          return EXT_CONTINUE
  
      def before_insert(self, mapper, connection, instance):
          """Receive an object instance before that instance is inserted
          into its table.
  
          This is a good place to set up primary key values and such
          that aren't handled otherwise.
  
          Column-based attributes can be modified within this method
          which will result in the new value being inserted.  However
          *no* changes to the overall flush plan can be made, and
          manipulation of the ``Session`` will not have the desired effect.
          To manipulate the ``Session`` within an extension, use
          ``SessionExtension``.
  
          The return value is only significant within the ``MapperExtension``
          chain; the parent mapper's behavior isn't modified by this method.
  
          """
  
          return EXT_CONTINUE
  
      def after_insert(self, mapper, connection, instance):
          """Receive an object instance after that instance is inserted.
  
          The return value is only significant within the ``MapperExtension``
          chain; the parent mapper's behavior isn't modified by this method.
  
          """
  
          return EXT_CONTINUE
  
      def before_update(self, mapper, connection, instance):
          """Receive an object instance before that instance is updated.
  
          Note that this method is called for all instances that are marked as
          "dirty", even those which have no net changes to their column-based
          attributes. An object is marked as dirty when any of its column-based
          attributes have a "set attribute" operation called or when any of its
          collections are modified. If, at update time, no column-based
          attributes have any net changes, no UPDATE statement will be issued.
          This means that an instance being sent to before_update is *not* a
          guarantee that an UPDATE statement will be issued (although you can
          affect the outcome here).
  
          To detect if the column-based attributes on the object have net
          changes, and will therefore generate an UPDATE statement, use
          ``object_session(instance).is_modified(instance,
          include_collections=False)``.
  
          Column-based attributes can be modified within this method
          which will result in the new value being updated.  However
          *no* changes to the overall flush plan can be made, and
          manipulation of the ``Session`` will not have the desired effect.
          To manipulate the ``Session`` within an extension, use
          ``SessionExtension``.
  
          The return value is only significant within the ``MapperExtension``
          chain; the parent mapper's behavior isn't modified by this method.
  
          """
  
          return EXT_CONTINUE
  
      def after_update(self, mapper, connection, instance):
          """Receive an object instance after that instance is updated.
  
          The return value is only significant within the ``MapperExtension``
          chain; the parent mapper's behavior isn't modified by this method.
  
          """
  
          return EXT_CONTINUE
  
      def before_delete(self, mapper, connection, instance):
          """Receive an object instance before that instance is deleted.
  
          Note that *no* changes to the overall flush plan can be made
          here; and manipulation of the ``Session`` will not have the
          desired effect. To manipulate the ``Session`` within an
          extension, use ``SessionExtension``.
  
          The return value is only significant within the ``MapperExtension``
          chain; the parent mapper's behavior isn't modified by this method.
  
          """
  
          return EXT_CONTINUE
  
      def after_delete(self, mapper, connection, instance):
          """Receive an object instance after that instance is deleted.
  
          The return value is only significant within the ``MapperExtension``
          chain; the parent mapper's behavior isn't modified by this method.
  
          """
  
          return EXT_CONTINUE
  
  
  @util.langhelpers.dependency_for("sqlalchemy.orm.interfaces")
  class SessionExtension(object):
  
      """Base implementation for :class:`.Session` event hooks.
  
      .. deprecated:: 0.7
  
         :class:`.SessionExtension` is deprecated and will be removed in a future
         release.  Please refer to :func:`.event.listen` in conjunction with
         the :class:`.SessionEvents` listener interface.
  
      Subclasses may be installed into a :class:`.Session` (or
      :class:`.sessionmaker`) using the ``extension`` keyword
      argument::
  
          from sqlalchemy.orm.interfaces import SessionExtension
  
          class MySessionExtension(SessionExtension):
              def before_commit(self, session):
                  print "before commit!"
  
          Session = sessionmaker(extension=MySessionExtension())
  
      The same :class:`.SessionExtension` instance can be used
      with any number of sessions.
  
      """
  
      @classmethod
      def _adapt_listener(cls, self, listener):
          for meth in [
              "before_commit",
              "after_commit",
              "after_rollback",
              "before_flush",
              "after_flush",
              "after_flush_postexec",
              "after_begin",
              "after_attach",
              "after_bulk_update",
              "after_bulk_delete",
          ]:
              me_meth = getattr(SessionExtension, meth)
              ls_meth = getattr(listener, meth)
  
              if not util.methods_equivalent(me_meth, ls_meth):
                  util.warn_deprecated(
                      "SessionExtension.%s is deprecated.  The "
                      "SessionExtension class will be removed in a future "
                      "release.  Please transition to the @event interface, "
                      "using @event.listens_for(Session, '%s')." % (meth, meth)
                  )
  
                  event.listen(self, meth, getattr(listener, meth))
  
      def before_commit(self, session):
          """Execute right before commit is called.
  
          Note that this may not be per-flush if a longer running
          transaction is ongoing."""
  
      def after_commit(self, session):
          """Execute after a commit has occurred.
  
          Note that this may not be per-flush if a longer running
          transaction is ongoing."""
  
      def after_rollback(self, session):
          """Execute after a rollback has occurred.
  
          Note that this may not be per-flush if a longer running
          transaction is ongoing."""
  
      def before_flush(self, session, flush_context, instances):
          """Execute before flush process has started.
  
          `instances` is an optional list of objects which were passed to
          the ``flush()`` method. """
  
      def after_flush(self, session, flush_context):
          """Execute after flush has completed, but before commit has been
          called.
  
          Note that the session's state is still in pre-flush, i.e. 'new',
          'dirty', and 'deleted' lists still show pre-flush state as well
          as the history settings on instance attributes."""
  
      def after_flush_postexec(self, session, flush_context):
          """Execute after flush has completed, and after the post-exec
          state occurs.
  
          This will be when the 'new', 'dirty', and 'deleted' lists are in
          their final state.  An actual commit() may or may not have
          occurred, depending on whether or not the flush started its own
          transaction or participated in a larger transaction. """
  
      def after_begin(self, session, transaction, connection):
          """Execute after a transaction is begun on a connection
  
          `transaction` is the SessionTransaction. This method is called
          after an engine level transaction is begun on a connection. """
  
      def after_attach(self, session, instance):
          """Execute after an instance is attached to a session.
  
          This is called after an add, delete or merge. """
  
      def after_bulk_update(self, session, query, query_context, result):
          """Execute after a bulk update operation to the session.
  
          This is called after a session.query(...).update()
  
          `query` is the query object that this update operation was
          called on. `query_context` was the query context object.
          `result` is the result object returned from the bulk operation.
          """
  
      def after_bulk_delete(self, session, query, query_context, result):
          """Execute after a bulk delete operation to the session.
  
          This is called after a session.query(...).delete()
  
          `query` is the query object that this delete operation was
          called on. `query_context` was the query context object.
          `result` is the result object returned from the bulk operation.
          """
  
  
  @util.langhelpers.dependency_for("sqlalchemy.orm.interfaces")
  class AttributeExtension(object):
      """Base implementation for :class:`.AttributeImpl` event hooks, events
      that fire upon attribute mutations in user code.
  
      .. deprecated:: 0.7
  
         :class:`.AttributeExtension` is deprecated and will be removed in a
         future release.  Please refer to :func:`.event.listen` in conjunction
         with the :class:`.AttributeEvents` listener interface.
  
      :class:`.AttributeExtension` is used to listen for set,
      remove, and append events on individual mapped attributes.
      It is established on an individual mapped attribute using
      the `extension` argument, available on
      :func:`.column_property`, :func:`.relationship`, and
      others::
  
          from sqlalchemy.orm.interfaces import AttributeExtension
          from sqlalchemy.orm import mapper, relationship, column_property
  
          class MyAttrExt(AttributeExtension):
              def append(self, state, value, initiator):
                  print "append event !"
                  return value
  
              def set(self, state, value, oldvalue, initiator):
                  print "set event !"
                  return value
  
          mapper(SomeClass, sometable, properties={
              'foo':column_property(sometable.c.foo, extension=MyAttrExt()),
              'bar':relationship(Bar, extension=MyAttrExt())
          })
  
      Note that the :class:`.AttributeExtension` methods
      :meth:`~.AttributeExtension.append` and
      :meth:`~.AttributeExtension.set` need to return the
      ``value`` parameter. The returned value is used as the
      effective value, and allows the extension to change what is
      ultimately persisted.
  
      AttributeExtension is assembled within the descriptors associated
      with a mapped class.
  
      """
  
      active_history = True
      """indicates that the set() method would like to receive the 'old' value,
      even if it means firing lazy callables.
  
      Note that ``active_history`` can also be set directly via
      :func:`.column_property` and :func:`.relationship`.
  
      """
  
      @classmethod
      def _adapt_listener(cls, self, listener):
          for meth in ["append", "remove", "set"]:
              me_meth = getattr(AttributeExtension, meth)
              ls_meth = getattr(listener, meth)
  
              if not util.methods_equivalent(me_meth, ls_meth):
                  util.warn_deprecated(
                      "AttributeExtension.%s is deprecated.  The "
                      "AttributeExtension class will be removed in a future "
                      "release.  Please transition to the @event interface, "
                      "using @event.listens_for(Class.attribute, '%s')."
                      % (meth, meth)
                  )
  
          event.listen(
              self,
              "append",
              listener.append,
              active_history=listener.active_history,
              raw=True,
              retval=True,
          )
          event.listen(
              self,
              "remove",
              listener.remove,
              active_history=listener.active_history,
              raw=True,
              retval=True,
          )
          event.listen(
              self,
              "set",
              listener.set,
              active_history=listener.active_history,
              raw=True,
              retval=True,
          )
  
      def append(self, state, value, initiator):
          """Receive a collection append event.
  
          The returned value will be used as the actual value to be
          appended.
  
          """
          return value
  
      def remove(self, state, value, initiator):
          """Receive a remove event.
  
          No return value is defined.
  
          """
          pass
  
      def set(self, state, value, oldvalue, initiator):
          """Receive a set event.
  
          The returned value will be used as the actual value to be
          set.
  
          """
          return value
  