class City(db.Model):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(30), unique=True)
# optional
def __repr__(self):
return f'City <id={self.id}, name={self.name}>'
class Post(db.Model):
id = db.Column(db.Integer, primary_key=True)
title = db.Column(db.String(50))
body = db.Column(db.Text)
comments = db.relationship('Comment',
back_populates='post',
cascade='all, delete-orphan') # collection
class Writer(db.Model):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(64))
books = db.relationship('Book', back_populates='writer')
# optional
def __repr__(self):
return f'Writer <id={self.id}, name={self.name}>'
class Capital(db.Model):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(30), unique=True)
country_id = db.Column(db.Integer, db.ForeignKey('country.id'))
country = db.relationship('Country', back_populates='capital')
# optional
def __repr__(self):
return f'Capital <id={self.id}, name={self.name}, country={self.country.name if self.country else None}>'
class Citizen(db.Model):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(30), unique=True)
city_id = db.Column(db.Integer, db.ForeignKey('city.id'))
city = db.relationship('City') # scalar
# optional
def __repr__(self):
return f'Citizen <id={self.id}, name={self.name}>'
class Book(db.Model):
id = db.Column(db.Integer, primary_key=True)
title = db.Column(db.String(64), index=True)
writer_id = db.Column(db.Integer, db.ForeignKey('writer.id'))
writer = db.relationship('Writer', back_populates='books')
# optional
def __repr__(self):
return f'Book <id={self.id}, title={self.title}>'
class Article(db.Model):
id = db.Column(db.Integer, primary_key=True)
title = db.Column(db.String(64), index=True)
body = db.Column(db.Text)
author_id = db.Column(db.Integer, db.ForeignKey('author.id'))
# optional
def __repr__(self):
return f'Article <id={self.id}, title={self.title}, body={self.body}, author_id={self.author_id}>'
class Country(db.Model):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(30), unique=True)
capital = db.relationship('Capital',
uselist=False,
back_populates='country')
# optional
def __repr__(self):
return f'Country <id={self.id}, name={self.name}, capital=[{self.capital}]>'