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Module « sqlalchemy.orm »

Fonction clear_mappers - module sqlalchemy.orm

Signature de la fonction clear_mappers

def clear_mappers() -> 'None' 

Description

help(sqlalchemy.orm.clear_mappers)

Remove all mappers from all classes.

.. versionchanged:: 1.4  This function now locates all
   :class:`_orm.registry` objects and calls upon the
   :meth:`_orm.registry.dispose` method of each.

This function removes all instrumentation from classes and disposes
of their associated mappers.  Once called, the classes are unmapped
and can be later re-mapped with new mappers.

:func:`.clear_mappers` is *not* for normal use, as there is literally no
valid usage for it outside of very specific testing scenarios. Normally,
mappers are permanent structural components of user-defined classes, and
are never discarded independently of their class.  If a mapped class
itself is garbage collected, its mapper is automatically disposed of as
well. As such, :func:`.clear_mappers` is only for usage in test suites
that re-use the same classes with different mappings, which is itself an
extremely rare use case - the only such use case is in fact SQLAlchemy's
own test suite, and possibly the test suites of other ORM extension
libraries which intend to test various combinations of mapper construction
upon a fixed set of classes.

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