从 sqlalchemy 更改为 postgresql 并得到关系错误
changinge from sqlalchemy to postgresql and got the error with relationship
您好，我有数据库多对多关系和最好的一对一关系，它与 sqlalchemy 完美配合，现在我将其更改为 postgresql 并得到
errornvalidRequestError: 在关系 Users.is_bestfriend 上，'dynamic' 加载程序不能与 many-to-one/one-to-one 关系一起使用 and/or uselist=False。
error:
Traceback (most recent call last)
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1836, in __call__
return self.wsgi_app(environ, start_response)
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1820, in wsgi_app
response = self.make_response(self.handle_exception(e))
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1403, in handle_exception
reraise(exc_type, exc_value, tb)
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1817, in wsgi_app
response = self.full_dispatch_request()
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1477, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1381, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1475, in full_dispatch_request
rv = self.dispatch_request()
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1461, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "/usr/local/lib/python2.7/dist-packages/flask_login.py", line 756, in decorated_view
elif not current_user.is_authenticated():
File "/usr/local/lib/python2.7/dist-packages/werkzeug/local.py", line 338, in __getattr__
return getattr(self._get_current_object(), name)
File "/usr/local/lib/python2.7/dist-packages/werkzeug/local.py", line 297, in _get_current_object
return self.__local()
File "/usr/local/lib/python2.7/dist-packages/flask_login.py", line 46, in <lambda>
current_user = LocalProxy(lambda: _get_user())
File "/usr/local/lib/python2.7/dist-packages/flask_login.py", line 794, in _get_user
current_app.login_manager._load_user()
File "/usr/local/lib/python2.7/dist-packages/flask_login.py", line 363, in _load_user
return self.reload_user()
File "/usr/local/lib/python2.7/dist-packages/flask_login.py", line 325, in reload_user
user = self.user_callback(user_id)
File "/home/peg/flask-Alembic/app/auth/view.py", line 60, in load_user
return Users.query.get(int(user_id))
File "/usr/local/lib/python2.7/dist-packages/flask_sqlalchemy/__init__.py", line 426, in __get__
mapper = orm.class_mapper(type)
File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/base.py", line 378, in class_mapper
mapper = _inspect_mapped_class(class_, configure=configure)
File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/base.py", line 355, in _inspect_mapped_class
mapper._configure_all()
File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/mapper.py", line 1129, in _configure_all
configure_mappers()
File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/mapper.py", line 2544, in configure_mappers
mapper._post_configure_properties()
File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/mapper.py", line 1660, in _post_configure_properties
prop.post_instrument_class(self)
File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/interfaces.py", line 481, in post_instrument_class
self.strategy.init_class_attribute(mapper)
File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/dynamic.py", line 31, in init_class_attribute
"uselist=False." % self.parent_property)
InvalidRequestError: On relationship Users.is_bestfriend, 'dynamic' loaders cannot be used with many-to-one/one-to-one relationships and/or uselist=False.
model.py:
friends = db.Table('friends',
db.Column('user_id', db.Integer, db.ForeignKey('users.id')),
db.Column('friend_id', db.Integer, db.ForeignKey('users.id'))
)
class Users(db.Model):
id = db.Column(db.Integer, primary_key = True)
name = db.Column(db.String(50), index=True)
age= db.Column(db.Integer )
email = db.Column(db.String(50),index=True, unique= True)
bestfriend_id = db.Column(db.Integer, db.ForeignKey('users.id'))
is_bestfriend = db.relationship( 'Users',lazy='dynamic',remote_side=id, post_update=True)
is_friend = db.relationship('Users', #defining the relationship, Users is left side entity
secondary = friends, #indecates association table
primaryjoin = (friends.c.user_id == id), #condition linking the left side entity
secondaryjoin = (friends.c.friend_id == id),#cond if link right.s ent. with assoc table
backref = db.backref('friends', lazy = 'dynamic'),#how accessed from right
lazy = 'dynamic'
)
#funcitons for bestfriend management
def are_bestfriends(self, user):
return self.is_bestfriend == user
#best friends management
def be_bestfriend(self, user):
if not self.are_bestfriends(user):
self.is_bestfriend = [user]
user.is_bestfriend = [self]
return self
view.py:
#best_freinds
@layout.route('/bestFriend/<name>')
@login_required
def bestFriend(name):
user = Users.query.filter_by(name = name).first()
if user is None:
flash('User %s not found.' % name)
return redirect(url_for('index'))
if user == g.user:
flash('You can\'t Best Friend yourself!')
return redirect(url_for('user', page=1,sortby='normal'))
u = g.user.be_bestfriend(user) #got error here if I remove lazy='dynamic'
if u is None:
flash('Cannot be best Friend ' + name + '.')
return redirect(url_for('user', page=1,sortby='normal'))
db.session.add(u)
db.session.commit()
flash('You are now BestFriend with ' + name + '!')
return redirect(url_for('user', page=1,sortby='normal'))
如错误信息所述，您不能在关系中使用 lazy='dynamic' 和 uselist=False；无论如何它只会加载一个对象，不需要对其进行动态查询。从 is_bestfriend 关系中删除 lazy='dynamic'。
您好，我有数据库多对多关系和最好的一对一关系，它与 sqlalchemy 完美配合，现在我将其更改为 postgresql 并得到
errornvalidRequestError: 在关系 Users.is_bestfriend 上，'dynamic' 加载程序不能与 many-to-one/one-to-one 关系一起使用 and/or uselist=False。
error:
Traceback (most recent call last)
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1836, in __call__
return self.wsgi_app(environ, start_response)
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1820, in wsgi_app
response = self.make_response(self.handle_exception(e))
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1403, in handle_exception
reraise(exc_type, exc_value, tb)
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1817, in wsgi_app
response = self.full_dispatch_request()
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1477, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1381, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1475, in full_dispatch_request
rv = self.dispatch_request()
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1461, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "/usr/local/lib/python2.7/dist-packages/flask_login.py", line 756, in decorated_view
elif not current_user.is_authenticated():
File "/usr/local/lib/python2.7/dist-packages/werkzeug/local.py", line 338, in __getattr__
return getattr(self._get_current_object(), name)
File "/usr/local/lib/python2.7/dist-packages/werkzeug/local.py", line 297, in _get_current_object
return self.__local()
File "/usr/local/lib/python2.7/dist-packages/flask_login.py", line 46, in <lambda>
current_user = LocalProxy(lambda: _get_user())
File "/usr/local/lib/python2.7/dist-packages/flask_login.py", line 794, in _get_user
current_app.login_manager._load_user()
File "/usr/local/lib/python2.7/dist-packages/flask_login.py", line 363, in _load_user
return self.reload_user()
File "/usr/local/lib/python2.7/dist-packages/flask_login.py", line 325, in reload_user
user = self.user_callback(user_id)
File "/home/peg/flask-Alembic/app/auth/view.py", line 60, in load_user
return Users.query.get(int(user_id))
File "/usr/local/lib/python2.7/dist-packages/flask_sqlalchemy/__init__.py", line 426, in __get__
mapper = orm.class_mapper(type)
File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/base.py", line 378, in class_mapper
mapper = _inspect_mapped_class(class_, configure=configure)
File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/base.py", line 355, in _inspect_mapped_class
mapper._configure_all()
File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/mapper.py", line 1129, in _configure_all
configure_mappers()
File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/mapper.py", line 2544, in configure_mappers
mapper._post_configure_properties()
File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/mapper.py", line 1660, in _post_configure_properties
prop.post_instrument_class(self)
File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/interfaces.py", line 481, in post_instrument_class
self.strategy.init_class_attribute(mapper)
File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/dynamic.py", line 31, in init_class_attribute
"uselist=False." % self.parent_property)
InvalidRequestError: On relationship Users.is_bestfriend, 'dynamic' loaders cannot be used with many-to-one/one-to-one relationships and/or uselist=False.
model.py:
friends = db.Table('friends',
db.Column('user_id', db.Integer, db.ForeignKey('users.id')),
db.Column('friend_id', db.Integer, db.ForeignKey('users.id'))
)
class Users(db.Model):
id = db.Column(db.Integer, primary_key = True)
name = db.Column(db.String(50), index=True)
age= db.Column(db.Integer )
email = db.Column(db.String(50),index=True, unique= True)
bestfriend_id = db.Column(db.Integer, db.ForeignKey('users.id'))
is_bestfriend = db.relationship( 'Users',lazy='dynamic',remote_side=id, post_update=True)
is_friend = db.relationship('Users', #defining the relationship, Users is left side entity
secondary = friends, #indecates association table
primaryjoin = (friends.c.user_id == id), #condition linking the left side entity
secondaryjoin = (friends.c.friend_id == id),#cond if link right.s ent. with assoc table
backref = db.backref('friends', lazy = 'dynamic'),#how accessed from right
lazy = 'dynamic'
)
#funcitons for bestfriend management
def are_bestfriends(self, user):
return self.is_bestfriend == user
#best friends management
def be_bestfriend(self, user):
if not self.are_bestfriends(user):
self.is_bestfriend = [user]
user.is_bestfriend = [self]
return self
view.py:
#best_freinds
@layout.route('/bestFriend/<name>')
@login_required
def bestFriend(name):
user = Users.query.filter_by(name = name).first()
if user is None:
flash('User %s not found.' % name)
return redirect(url_for('index'))
if user == g.user:
flash('You can\'t Best Friend yourself!')
return redirect(url_for('user', page=1,sortby='normal'))
u = g.user.be_bestfriend(user) #got error here if I remove lazy='dynamic'
if u is None:
flash('Cannot be best Friend ' + name + '.')
return redirect(url_for('user', page=1,sortby='normal'))
db.session.add(u)
db.session.commit()
flash('You are now BestFriend with ' + name + '!')
return redirect(url_for('user', page=1,sortby='normal'))
如错误信息所述，您不能在关系中使用 lazy='dynamic' 和 uselist=False；无论如何它只会加载一个对象，不需要对其进行动态查询。从 is_bestfriend 关系中删除 lazy='dynamic'。