properties.py 文件源码

def create_lazy_clause(table, primaryjoin, secondaryjoin, foreignkey):
    binds = {}
    def visit_binary(binary):
        circular = isinstance(binary.left, schema.Column) and isinstance(binary.right, schema.Column) and binary.left.table is binary.right.table
        if isinstance(binary.left, schema.Column) and ((not circular and binary.left.table is table) or (circular and binary.right is foreignkey)):
            binary.left = binds.setdefault(binary.left,
                    sql.BindParamClause(binary.right.table.name + "_" + binary.right.name, None, shortname = binary.left.name))
            binary.swap()

        if isinstance(binary.right, schema.Column) and ((not circular and binary.right.table is table) or (circular and binary.left is foreignkey)):
            binary.right = binds.setdefault(binary.right,
                    sql.BindParamClause(binary.left.table.name + "_" + binary.left.name, None, shortname = binary.right.name))

    if secondaryjoin is not None:
        lazywhere = sql.and_(primaryjoin, secondaryjoin)
    else:
        lazywhere = primaryjoin
    lazywhere = lazywhere.copy_container()
    li = BinaryVisitor(visit_binary)
    lazywhere.accept_visitor(li)
    return (lazywhere, binds)