Method history

lib/sqlalchemy/orm/state.py:1091–1116

Return the current **pre-flush** change history for this attribute, via the :class:`.History` interface. This method will **not** emit loader callables if the value of the attribute is unloaded. .. note:: The attribute history system tracks changes on a

(self)

    @property
    def history(self) -> History:
        """Return the current **pre-flush** change history for
        this attribute, via the :class:`.History` interface.

        This method will **not** emit loader callables if the value of the
        attribute is unloaded.

        .. note::

            The attribute history system tracks changes on a **per flush
            basis**. Each time the :class:`.Session` is flushed, the history
            of each attribute is reset to empty.   The :class:`.Session` by
            default autoflushes each time a :class:`_query.Query` is invoked.
            For
            options on how to control this, see :ref:`session_flushing`.


        .. seealso::

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

            :func:`.attributes.get_history` - underlying function

        """
        return self.state.get_history(self.key, PASSIVE_NO_INITIALIZE)

    def load_history(self) -> History:
        """Return the current **pre-flush** change history for