Function _organize_states_for_save

lib/sqlalchemy/orm/persistence.py:210–287

Make an initial pass across a set of states for INSERT or UPDATE. This includes splitting out into distinct lists for each, calling before_insert/before_update, obtaining key information for each state including its dictionary, mapper, the connection to use for the execution per

(base_mapper, states, uowtransaction)

def _organize_states_for_save(base_mapper, states, uowtransaction):
    """Make an initial pass across a set of states for INSERT or
    UPDATE.

    This includes splitting out into distinct lists for
    each, calling before_insert/before_update, obtaining
    key information for each state including its dictionary,
    mapper, the connection to use for the execution per state,
    and the identity flag.

    """

    for state, dict_, mapper, connection in _connections_for_states(
        base_mapper, uowtransaction, states
    ):
        has_identity = bool(state.key)

        instance_key = state.key or mapper._identity_key_from_state(state)

        row_switch = update_version_id = None

        # call before_XXX extensions
        if not has_identity:
            mapper.dispatch.before_insert(mapper, connection, state)
        else:
            mapper.dispatch.before_update(mapper, connection, state)

        if mapper._validate_polymorphic_identity:
            mapper._validate_polymorphic_identity(mapper, state, dict_)

        # detect if we have a "pending" instance (i.e. has
        # no instance_key attached to it), and another instance
        # with the same identity key already exists as persistent.
        # convert to an UPDATE if so.
        if (
            not has_identity
            and instance_key in uowtransaction.session.identity_map
        ):
            instance = uowtransaction.session.identity_map[instance_key]
            existing = attributes.instance_state(instance)

            if not uowtransaction.was_already_deleted(existing):
                if not uowtransaction.is_deleted(existing):
                    util.warn(
                        "New instance %s with identity key %s conflicts "
                        "with persistent instance %s"
                        % (state_str(state), instance_key, state_str(existing))
                    )
                else:
                    base_mapper._log_debug(
                        "detected row switch for identity %s.  "
                        "will update %s, remove %s from "
                        "transaction",
                        instance_key,
                        state_str(state),
                        state_str(existing),
                    )