我是sqlalchemy的新手.我已经按照教程创建了一个与mysql db关系的现有数据库的自动化
from sqlalchemy import create_engine, MetaData, Column, Table, ForeignKey
from sqlalchemy.ext.automap import automap_base, generate_relationship
from sqlalchemy.orm import relationship, backref
from config import constr, mytables
def _gen_relationship(base, direction, return_fn,
attrname, local_cls, refferred_cls, **kw):
return generate_relationship(base, direction, return_fn, attrname, local_cls, refferred_cls, **kw)
engine = create_engine(constr)
metadata = MetaData()
metadata.reflect(engine, only=mytables)
Base = automap_base(metadata=metadata)
Base.prepare(engine, reflect=True, generate_relationship=_gen_relationship)
Tableclass1 = Base.classes.table1
Tableclass2 = Base.classes.table2
Table2.ID映射到其中一table1列.但是,当我试图使用查询和加入table1和table2,它报告错误,说"无法找到任何外键关系".既然我知道了这两个表的关系,那么在创建类实例之后是否可以声明这种关系？或者有没有办法在查询功能中明确告诉这种关系？谢谢!