Question

如何使用flask-sqlalchemy 进行多对多查询

Answer 1

示例

from flask_sqlalchemy import SQLAlchemy
db = SQLAlchemy()

sc = db.Table('sc',
    db.Column('sno', db.String(10), db.ForeignKey('students.sno')),
    db.Column('cno', db.String(10), db.ForeignKey('courses.cno'))
    )


class Students(db.Model):
    __tablename__ = 'students'
    sno = db.Column(db.String(10), primary_key=True)
    sname = db.Column(db.String(10))
    
    
class Course(db.Model):
    __tablename__ = 'courses'
    cno = db.Column(db.String(10), primary_key=True)
    cname = db.Column(db.String(10), index=True)
    students = db.relationship('Student',
         secondary=sc,
         backref=db.backref('courses',lazy='dynamic'),
         lazy='dynamic'
         )
 
 #查询
student = Student.query.filter_by(sname=u'张三')  
courses  = student.courses.all()  #该学生选择的所有课程