SQL Alchemy Examples With Cascade Deleting

models.py

from . import db


# Many To Many

class Exam(db.Model):
    __tablename__ = 'exams'
    score = db.Column(db.Integer, nullable=False)

    student_id = db.Column(db.Integer, db.ForeignKey('students.id'), primary_key=True)
    course_no = db.Column(db.VARCHAR(5), db.ForeignKey('courses.c_no'), primary_key=True)

    student = db.relationship('Student', backref=db.backref('exams', cascade='all, delete'))
    course = db.relationship('Course', backref=db.backref('exams', cascade='all, delete'))


class Student(db.Model):
    __tablename__ = 'students'
    id = db.Column(db.Integer, primary_key=True)
    full_name = db.Column(db.String(64), nullable=False)


class Course(db.Model):
    __tablename__ = 'courses'
    c_no = db.Column(db.VARCHAR(5), nullable=False, primary_key=True)
    hours = db.Column(db.Integer, nullable=False)


# Many To One

class User(db.Model):
    __tablename__ = 'users'
    id = db.Column(db.Integer, primary_key=True)
    full_name = db.Column(db.String(64), nullable=False)

    # addresses = db.relationship('Address', backref=db.backref('user'))


class Address(db.Model):
    __tablename__ = 'addresses'
    id = db.Column(db.Integer, primary_key=True)
    address = db.Column(db.String(64), nullable=False)

    u_id = db.Column(db.Integer, db.ForeignKey('users.id'), nullable=False)
    user = db.relationship('User', backref=db.backref('addresses', cascade="all, delete"))