我有以下使用 flask-sqlalchemy 的 sqlalchemy 模型。我的日程表模型中有 3 个 Talentpref 项目。总是需要有 3 个,而且不少于 3 个。
class TalentPref(db.Model):
__tablename__ = 'talentpref'
id = db.Column(db.Integer, primary_key=True)
firstName = db.Column(db.String(80), unique=True)
lastName = db.Column(db.String(80), unique=True)
def __init__(self, firstName, lastName):
self.firstName = firstName
self.lastName = lastName
def __repr__(self):
return '<talentpref %r %r>' % (self.firstName, self.lastName)
class Schedule(db.Model):
__tablename__ = 'schedule'
id = db.Column(db.Integer, primary_key=True)
talentpref1_id = db.Column(db.Integer, db.ForeignKey('talentpref.id'))
talentpref2_id = db.Column(db.Integer, db.ForeignKey('talentpref.id'))
talentpref3_id = db.Column(db.Integer, db.ForeignKey('talentpref.id'))
talentpref1 = db.relationship("TalentPref", uselist=False, foreign_keys=talentpref1_id)
talentpref2 = db.relationship("TalentPref", uselist=False, foreign_keys=talentpref2_id)
talentpref3 = db.relationship("TalentPref", uselist=False, foreign_keys=talentpref3_id)
我正在使用 flask-restless 将调度模型作为 api 资源提供服务。当我按计划执行查询并要求按 Talentpref1__lastName 对查询进行排序时,我收到一个错误,该错误与我有多个引用“TalentPref”表的实例有关:
我可以在 id 列上成功使用查询字符串,如下所示:
/api/schedule?id=id&page=1&q={"order_by":[{"field":"id","direction":"desc"}]}
但是使用以下 http GET 查询字符串的查询失败:
/api/schedule?id=id&page=1&q={"order_by":[{"field":"talentpref1__lastName","direction":"desc"}]}
和:
Traceback (most recent call last):
File "/Users/myuser/Documents/pythonenvironments/venv/lib/python2.7/site-packages/flask_restless/views.py", line 1172, in _search
result = search(self.session, self.model, search_params)
File "/Users/myuser/Documents/pythonenvironments/venv/lib/python2.7/site-packages/flask_restless/search.py", line 587, in search
query = create_query(session, model, search_params, _ignore_order_by)
File "/Users/myuser/Documents/pythonenvironments/venv/lib/python2.7/site-packages/flask_restless/search.py", line 549, in create_query
_ignore_order_by)
File "/Users/myuser/Documents/pythonenvironments/venv/lib/python2.7/site-packages/flask_restless/search.py", line 498, in create_query
query = query.join(relation_model)
File "/Users/myuser/Documents/pythonenvironments/venv/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 1971, in join
from_joinpoint=from_joinpoint)
File "<string>", line 2, in _join
File "/Users/myuser/Documents/pythonenvironments/venv/lib/python2.7/site-packages/sqlalchemy/orm/base.py", line 201, in generate
fn(self, *args[1:], **kw)
File "/Users/myuser/Documents/pythonenvironments/venv/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2115, in _join
outerjoin, full, create_aliases, prop)
File "/Users/myuser/Documents/pythonenvironments/venv/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2188, in _join_left_to_right
self._join_to_left(l_info, left, right, onclause, outerjoin, full)
File "/Users/myuser/Documents/pythonenvironments/venv/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2317, in _join_to_left
"Tried joining to %s, but got: %s" % (right, ae))
InvalidRequestError: Could not find a FROM clause to join from. Tried
joining to <class 'app.model.TalentPref'>, but got: Can't determine
join between 'schedule' and 'talentpref'; tables have more than one
foreign key constraint relationship between them. Please specify the
'onclause' of this join explicitly.
有没有办法可以成功查询这种关系?