batch.py 文件源码

def _setup_referent(self, metadata, constraint):
        spec = constraint.elements[0]._get_colspec()
        parts = spec.split(".")
        tname = parts[-2]
        if len(parts) == 3:
            referent_schema = parts[0]
        else:
            referent_schema = None

        if tname != '_alembic_batch_temp':
            key = sql_schema._get_table_key(tname, referent_schema)
            if key in metadata.tables:
                t = metadata.tables[key]
                for elem in constraint.elements:
                    colname = elem._get_colspec().split(".")[-1]
                    if not t.c.contains_column(colname):
                        t.append_column(
                            Column(colname, sqltypes.NULLTYPE)
                        )
            else:
                Table(
                    tname, metadata,
                    *[Column(n, sqltypes.NULLTYPE) for n in
                        [elem._get_colspec().split(".")[-1]
                         for elem in constraint.elements]],
                    schema=referent_schema)