一對多

class Role(db.Model):
    """角色表"""
    __tablename__ = 'roles'

    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(64), unique=True)
    users = db.relationship('User', backref='role', lazy='dynamic')

class User(db.Model):
    """用戶表"""
    __tablename__ = 'users'
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(64), unique=True, index=True)

多對多

tb_student_course = db.Table('tb_student_course',
                             db.Column('student_id', db.Integer, db.ForeignKey('students.id')),
                             db.Column('course_id', db.Integer, db.ForeignKey('courses.id'))
                             )

class Student(db.Model):
    __tablename__ = "students"
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(64), unique=True)

    courses = db.relationship('Course', secondary=tb_student_course,
                              backref=db.backref('students', lazy='dynamic'),
                              lazy='dynamic')

class Course(db.Model):
    __tablename__ = "courses"
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(64), unique=True)

自關(guān)聯(lián)一對多

class Comment(db.Model):
    """評論"""
    __tablename__ = "comments"

    id = db.Column(db.Integer, primary_key=True)
    # 評論內(nèi)容
    content = db.Column(db.Text, nullable=False)
    # 父評論id
    parent_id = db.Column(db.Integer, db.ForeignKey("comments.id"))
    # 父評論(也是評論模型)
    parent = db.relationship("Comment", remote_side=[id],
                             backref=db.backref('childs', lazy='dynamic'))

# 測試代碼
if __name__ == '__main__':
    db.drop_all()
    db.create_all()

    com1 = Comment(content='我是主評論1')
    com2 = Comment(content='我是主評論2')
    com11 = Comment(content='我是回復(fù)主評論1的子評論1')
    com11.parent = com1
    com12 = Comment(content='我是回復(fù)主評論1的子評論2')
    com12.parent = com1

    db.session.add_all([com1, com2, com11, com12])
    db.session.commit()
    app.run(debug=True)

自關(guān)聯(lián)多對多

tb_user_follows = db.Table(
    "tb_user_follows",
    db.Column('follower_id', db.Integer, db.ForeignKey('info_user.id'), primary_key=True),  # 粉絲id
    db.Column('followed_id', db.Integer, db.ForeignKey('info_user.id'), primary_key=True)  # 被關(guān)注人的id
)

class User(db.Model):
    """用戶表"""
    __tablename__ = "info_user"

    id = db.Column(db.Integer, primary_key=True)  
    name = db.Column(db.String(32), unique=True, nullable=False)

    # 用戶所有的粉絲，添加了反向引用followed，代表用戶都關(guān)注了哪些人
    followers = db.relationship('User',
                                secondary=tb_user_follows,
                                primaryjoin=id == tb_user_follows.c.followed_id,
                                secondaryjoin=id == tb_user_follows.c.follower_id,
                                backref=db.backref('followed', lazy='dynamic'),
                                lazy='dynamic')