[英]Self-referential database with extra fields in sqlalchemy
I want to write a self-referential database structure for my messaging system using Flask and SQLAlchemy. 我想使用Flask和SQLAlchemy为我的消息传递系统编写一个自引用数据库结构。 Tables are very simple: 表格非常简单:
class User(db.Model):
__tablename__ = 'user'
id = Column(Integer, primary_key=True)
messages = db.relationship(...)
def addMessage (self, friend, message):
...
self.messages.append(friend)
return self
and message table is: 消息表是:
class Message (db.Model):
__tablename__ = 'message'
id = db.Column(db.Integer, primary_key=True)
emmiter_id = db.Column(db.Integer, db.ForeignKey('user.id'))
receiver_id = db.Column(db.Integer, db.ForeignKey('user.id'))
text = db.Column(db.Text)
I want to know how will the relationship with my user
table look like? 我想知道与user
表的关系如何? and how can I insert data on the message
table? 以及如何在message
表中插入数据?
This is what I wrote in user
table as relationship, but it is not working: 这是我在user
表中作为关系写的,但是它不起作用:
messages = db.relationship('User',
secondary = Message,
primaryjoin = (Message.emmiter_id == id),
secondaryjoin = (Message.receiver_id == id),
backref = db.backref('correspondence', lazy = 'dynamic'),
lazy = 'dynamic')
After working a lot around this problem I found the solution with primaryjoin between user table and message table. 在解决了许多问题之后,我找到了在用户表和消息表之间使用primaryjoin的解决方案。 Here is the working code 这是工作代码
# Messaging system table
class Message(db.Model):
__tablename__ = 'message'
emmiter_id = db.Column(db.Integer, db.ForeignKey('user.id'), primary_key=True)
recipient_id = db.Column(db.Integer, db.ForeignKey('user.id'), primary_key=True)
text = db.Column(db.Text, nullable=False)
and user table like : 和用户表,如:
class User (db.Model):
__tablename__ = 'user'
id = db.Column(db.Integer, primary_key=True)
inbox = db.relationship('Message',backref='sender', primaryjoin=id==Message.emmiter_id)
outbox = db.relationship('Message',backref='receiver', primaryjoin=id==Message.recipient_id)
and here is how you can add a message in message table: 这是在消息表中添加消息的方法:
message = Message(text="dsf", sender=sender , receiver=receiver)
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