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.
to use mapper.cascade_iterator() for this purpose as it was not really designed for that use case. Add docs to cascade_iterator() pointing to the recipe. fixes #3498
mapper_configured(), after_configured(), and before_configured().
- 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
if the name of the attribute being accessed is non-specific, thereby avoiding collisions on names like items, values, keys. fixes #3475
event where its invocation was moved to be after the class manager's instrumentation of the class, which is the opposite of what the documentation for the event explicitly states. The rationale for the switch was due to Declarative taking the step of setting up the full "instrumentation manager" for a class before it was mapped for the purpose of the new ``@declared_attr`` features described in :ref:`feature_3150`, but the change was also made against the classical use of :func:`.mapper` for consistency. However, SQLSoup relies upon the instrumentation event happening before any instrumentation under classical mapping. The behavior is reverted in the case of classical and declarative mapping, the latter implemented by using a simple memoization without using class manager. fixes #3388
to transient objects with attributes unset would leak NEVER_SET, and negated_contains_or_equals would do so for any transient object as the comparison used only the committed value. Repaired the NEVER_SET cases, fixes #3371, and also made negated_contains_or_equals() use state_attr_by_column() just like a non-negated comparison, fixes #3374
a much more modest outcome than what we started with. The work of create_row_processor() for ColumnProperty objects is essentially done at query setup time combined with some lookups in _instance_processor(). - to allow this change for deferred columns, deferred columns no longer search for themselves in the result. If they've been set up as deferred without any explicit directive to undefer them, then this is what was asked for. if we don't do this, then we're stuck with this performance penalty for all deferred columns which in the vast majority of typical use cases (e.g. loading large, legacy tables or tables with many/large very seldom used values) won't be present in the result and won't be accessed at all.