Flask数据库关系

基础配置

<code>from flask import Flask
from flask_sqlalchemy import SQLAlchemy
app = Flask(__name__)
db = SQLAlchemy(app)
app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql+pymysql://root:root@localhost/flask'</code>

一对多

<code>class Singer(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(70), unique=True)
    songs = db.relationship('Song', backref='singer')
class Song(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(70), unique=True)
    singer_id = db.Column(db.Integer, db.ForeignKey('singer.id'))</code>

多对一（不是必须时还是用与一对多吧）

比一对多的用法，会少一个从一里访问多的字段。

<code>class Citizen(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(70), unique=True)
    city_id = db.Column(db.Integer, db.ForeignKey('city.id'))
    city = db.relationship('City')
class Country(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(79), unique=True)
    capital = db.relationship('Capital', uselist=False)</code>

一对一

<code>class Country(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(79), unique=True)
    capital = db.relationship('Capital', uselist=False)
class Capital(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(70), unique=True)
    country_id = db.Column(db.Integer, db.ForeignKey('country.id'))
    country = db.relationship('Country'</code>

多对多

<code>association_table = db.Table(
    'association',
    db.Column('student_id', db.Integer, db.ForeignKey('student.id')),
    db.Column('teacher_id', db.Integer, db.ForeignKey('teacher.id'))
)
class Student(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(70), unique=True)
    grade = db.Column(db.String(20))
    teachers = db.relationship(
        'Teacher', secondary=association_table, backref='students')
class Teacher(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(70), unique=True)
    office = db.Column(db.String(20))</code>

Flask数据库关系

标签：int   key   foreign   iat   table   ons   ati   back   teacher