Flask的SQLAlchemy的数据库，去定义为：
class User(db.Model): __tablename__ = ‘wechat_users’ # Columns openid = db.Column(db.String(64), primary_key=True) province = db.Column(db.String(16)) headimgurl = db.Column(db.String(256)) language = db.Column(db.String(8)) city = db.Column(db.String(16)) country = db.Column(db.String(32)) sex = db.Column(db.SmallInteger) nickname = db.Column(db.String(128)) events = db.relationship(‘Event’, backref = ‘user’, lazy = ‘dynamic’) class Event(db.Model): __tablename__ = “events” # Columns id = db.Column(db.Integer, primary_key = True, autoincrement = True) #user_openid = db.Column(db.String(64)) user_openid = db.Column(db.String(64), db.ForeignKey(‘user.openid’)) |
结果运行出错：
Traceback (most recent call last): File “db_create.py”, line 24, in <module> db.create_all() File “/root/Envs/SIPEvents/lib/python2.7/site-packages/flask_sqlalchemy/__init__.py”, line 972, in create_all self._execute_for_all_tables(app, bind, ‘create_all’) File “/root/Envs/SIPEvents/lib/python2.7/site-packages/flask_sqlalchemy/__init__.py”, line 964, in _execute_for_all_tables op(bind=self.get_engine(app, bind), **extra) File “/root/Envs/SIPEvents/lib/python2.7/site-packages/sqlalchemy/sql/schema.py”, line 3745, in create_all tables=tables) File “/root/Envs/SIPEvents/lib/python2.7/site-packages/sqlalchemy/engine/base.py”, line 1856, in _run_visitor conn._run_visitor(visitorcallable, element, **kwargs) File “/root/Envs/SIPEvents/lib/python2.7/site-packages/sqlalchemy/engine/base.py”, line 1481, in _run_visitor **kwargs).traverse_single(element) File “/root/Envs/SIPEvents/lib/python2.7/site-packages/sqlalchemy/sql/visitors.py”, line 121, in traverse_single return meth(obj, **kw) File “/root/Envs/SIPEvents/lib/python2.7/site-packages/sqlalchemy/sql/ddl.py”, line 709, in visit_metadata [t for t in tables if self._can_create_table(t)]) File “/root/Envs/SIPEvents/lib/python2.7/site-packages/sqlalchemy/sql/ddl.py”, line 1058, in sort_tables_and_constraints dependent_on = fkc.referred_table File “/root/Envs/SIPEvents/lib/python2.7/site-packages/sqlalchemy/sql/schema.py”, line 2855, in referred_table return self.elements[0].column.table File “/root/Envs/SIPEvents/lib/python2.7/site-packages/sqlalchemy/util/langhelpers.py”, line 754, in __get__ obj.__dict__[self.__name__] = result = self.fget(obj) File “/root/Envs/SIPEvents/lib/python2.7/site-packages/sqlalchemy/sql/schema.py”, line 1824, in column tablekey) sqlalchemy.exc.NoReferencedTableError: Foreign key associated with column ‘events.user_openid’ could not find table ‘user’ with which to generate a foreign key to target column ‘openid’ (SIPEvents) ➜ SIPEvents |
搜：
sqlalchemy.exc.NoReferencedTableError: Foreign key associated with column
参考：
python – SQLalchemy not find table for creating foreign key – Stack Overflow
后来去改为：
#user_openid = db.Column(db.String(64), db.ForeignKey(‘user.openid’)) user_openid = db.Column(db.String(64), db.ForeignKey(‘wechat_users.openid’)) |
就可以了。
［总结］
此处，对于：
class Event(db.Model): __tablename__ = “events” user_openid = db.Column(db.String(64), db.ForeignKey(‘user.openid’)) |
内部的逻辑是：
对于ForeignKey，是去外部数据库中，找对应的属性的
此处，如果外部的数据，没有制定__tablename__，则默认就是数据库名字本身
class User(db.Model): # Columns openid = db.Column(db.String(64), primary_key=True) |
此时，估计用：
user_openid = db.Column(db.String(64), db.ForeignKey(‘user.openid’)) |
就是可以的。
但是我此处，已经是制定了User表格的表名为：wechat_users
class User(db.Model): __tablename__ = ‘wechat_users’ # Columns openid = db.Column(db.String(64), primary_key=True) |
所以此处，只能通过：
<code>user_openid = db.Column(db.String(64), db.ForeignKey('wechat_users.openid'))
</code>去找到对应的表，表中的键。
另外，如果一个表，没有制定表名，则好像内置的表名，是将驼峰法命名的名字，换成小写字母的，下划线分割的名字，比如：
中的：
ListType
内部自动生成的表名是：list_type
（而不是listtype）
－》
最好的办法是：
对于自己的表，自己去用__tablename__制定自己的表名
（而不要让SQLAlchemy隐式地帮你生成表名）
转载请注明：在路上 » ［已解决］Flask的SQLAlchemy数据库出错：sqlalchemy.exc.NoReferencedTableError: Foreign key associated with column ‘events.user_openid’ could not find table ‘user’ with which to generate a foreign key to target column ‘openid’