Function _collect_update_commands

lib/sqlalchemy/orm/persistence.py:426–637

Identify sets of values to use in UPDATE statements for a list of states. This function works intricately with the history system to determine exactly what values should be updated as well as how the row should be matched within an UPDATE statement. Includes some tricky scenari

(
    uowtransaction,
    table,
    states_to_update,
    *,
    bulk=False,
    use_orm_update_stmt=None,
    include_bulk_keys=(),
)

def _collect_update_commands(
    uowtransaction,
    table,
    states_to_update,
    *,
    bulk=False,
    use_orm_update_stmt=None,
    include_bulk_keys=(),
):
    """Identify sets of values to use in UPDATE statements for a
    list of states.

    This function works intricately with the history system
    to determine exactly what values should be updated
    as well as how the row should be matched within an UPDATE
    statement.  Includes some tricky scenarios where the primary
    key of an object might have been changed.

    """

    for (
        state,
        state_dict,
        mapper,
        connection,
        update_version_id,
    ) in states_to_update:
        if table not in mapper._pks_by_table:
            continue

        pks = mapper._pks_by_table[table]

        if (
            use_orm_update_stmt is not None
            and not use_orm_update_stmt._maintain_values_ordering
        ):
            # TODO: ordered values, etc
            # ORM bulk_persistence will raise for the maintain_values_ordering
            # case right now
            value_params = use_orm_update_stmt._values
        else:
            value_params = {}

        propkey_to_col = mapper._propkey_to_col[table]

        if bulk:
            # keys here are mapped attribute keys, so
            # look at mapper attribute keys for pk
            params = {
                propkey_to_col[propkey].key: state_dict[propkey]
                for propkey in set(propkey_to_col)
                .intersection(state_dict)
                .difference(mapper._pk_attr_keys_by_table[table])
            }
            has_all_defaults = True
        else:
            params = {}
            for propkey in set(propkey_to_col).intersection(