Function get_history

lib/sqlalchemy/orm/attributes.py:2551–2588

Return a :class:`.History` record for the given object and attribute key. This is the **pre-flush** history for a given attribute, which is reset each time the :class:`.Session` flushes changes to the current database transaction. .. note:: Prefer to use the :attr:`.At

(
    obj: object, key: str, passive: PassiveFlag = PASSIVE_OFF
)

def get_history(
    obj: object, key: str, passive: PassiveFlag = PASSIVE_OFF
) -> History:
    """Return a :class:`.History` record for the given object
    and attribute key.

    This is the **pre-flush** history for a given attribute, which is
    reset each time the :class:`.Session` flushes changes to the
    current database transaction.

    .. note::

        Prefer to use the :attr:`.AttributeState.history` and
        :meth:`.AttributeState.load_history` accessors to retrieve the
        :class:`.History` for instance attributes.


    :param obj: an object whose class is instrumented by the
      attributes package.

    :param key: string attribute name.

    :param passive: indicates loading behavior for the attribute
       if the value is not already present.   This is a
       bitflag attribute, which defaults to the symbol
       :attr:`.PASSIVE_OFF` indicating all necessary SQL
       should be emitted.

    .. seealso::

        :attr:`.AttributeState.history`

        :meth:`.AttributeState.load_history` - retrieve history
        using loader callables if the value is not locally present.

    """

    return get_state_history(instance_state(obj), key, passive)


def get_state_history(