kinds of internal column loader options within internal logging. fixes #3539
which indicates to the ORM that a positive set of None should be persisted as the value NULL, instead of omitting the column from the INSERT statement. This feature is used both as part of the implementation for :ticket:`3514` as well as a standalone feature available on any type. fixes #3250 - add new documentation section illustrating the "how to force null" use case of #3250 - alter our change from #3514 so that the class-level flag is now called "should_evaluate_none"; so that "evaluates_none" is now a generative method.
expression element which is late-evaluated at compile time. Previously, the function was only a conversion function which would handle different expression inputs by returning either a :class:`.Label` of a column-oriented expression or a copy of a given :class:`.BindParameter` object, which in particular prevented the operation from being logically maintained when an ORM-level expression transformation would convert a column to a bound parameter (e.g. for lazy loading). fixes #3531
:meth:`.Session.bulk_save_objects` and related bulk methods have been scaled back to the extent that this functionality is not currently used, e.g. checks for column default values to be fetched after an INSERT or UPDATE statement. fixes #3526
column that had some kind of "fetch on update" value and was not locally present in the given object would cause an AttributeError within the operation. fixes #3525
unambiguous tracking of all object lifecycle state transitions in terms of the :class:`.Session` itself, e.g. pending, transient, persistent, detached. The state of the object within each event is also defined. fixes #2677 - Added a new session lifecycle state :term:`deleted`. This new state represents an object that has been deleted from the :term:`persistent` state and will move to the :term:`detached` state once the transaction is committed. This resolves the long-standing issue that objects which were deleted existed in a gray area between persistent and detached. The :attr:`.InstanceState.persistent` accessor will **no longer** report on a deleted object as persistent; the :attr:`.InstanceState.deleted` accessor will instead be True for these objects, until they become detached. - The :paramref:`.Session.weak_identity_map` parameter is deprecated. See the new recipe at :ref:`session_referencing_behavior` for an event-based approach to maintaining strong identity map behavior. references #3517
or mapped instances into contexts where they are interpreted as SQL bound parameters; a new exception is raised for this. fixes #3321
- Fixes to the ORM and to the postgresql JSON type regarding the ``None`` constant in conjunction with the Postgresql :class:`.JSON` type. When the :paramref:`.JSON.none_as_null` flag is left at its default value of ``False``, the ORM will now correctly insert the Json "'null'" string into the column whenever the value on the ORM object is set to the value ``None`` or when the value ``None`` is used with :meth:`.Session.bulk_insert_mappings`, **including** if the column has a default or server default on it. This makes use of a new type-level flag "evaluates_none" which is implemented by the JSON type based on the none_as_null flag. fixes #3514 - Added a new constant :attr:`.postgresql.JSON.NULL`, indicating that the JSON NULL value should be used for a value regardless of other settings. part of fixes #3514