flask 模型关系一对多的关联

模型关系

• 一对多的关联

from flask import Flask from flask_script import Manager from flask_sqlalchemy import SQLAlchemy from flask_migrate import Migrate, MigrateCommand import os app = Flask(__name__) manager = Manager(app) base_dir = os.path.abspath(os.path.dirname(__file__)) database_uri = "sqlite:///"+ os.path.join(base_dir, "data.sqlite") #app.config["SQLALCHEMY_COMMIT_ON_TEARDOWN"] = True app.config["SQLALCHEMY_DATABASE_URI"] = database_uri db = SQLAlchemy(app) migrate = Migrate(app, db) manager.add_command("db", MigrateCommand) class Student(db.Model): id = db.Column(db.Integer, primary_key=True) name = db.Column(db.String(20), unique=True) #dynamic（不加载记录，但提供加载记录的查询） articles = db.relationship("Article", backref="stu",lazy="dynamic") class Article(db.Model): id = db.Column(db.Integer, primary_key=True) content = db.Column(db.Text) sid = db.Column(db.Integer, db.ForeignKey("student.id"))

多对多的关联

from flask import Flask from flask_script import Manager from flask_migrate import Migrate,MigrateCommand from flask_sqlalchemy import SQLAlchemy import os app = Flask(__name__) manager = Manager(app) base_dir = os.path.abspath(os.path.dirname(__file__)) database_uri = "sqlite:///"+os.path.join(base_dir, "data.sqlite") app.config["SQLALCHEMY_DATABASE_URI"] = database_uri db = SQLAlchemy(app) migrate = Migrate(app, db) manager.add_command("db", MigrateCommand) class Student(db.Model): id = db.Column(db.Integer, primary_key=True) name = db.Column(db.String(20), unique=True) course = db.relationship("Course", secondary = "xuankebiao", backref = db.backref("students",lazy="dynamic"),lazy = "dynamic") class Course(db.Model): id = db.Column(db.Integer, primary_key=True) name = db.Column(db.String(20), unique=True) #声明中间关联表 xuankebiao = db.Table("xuankebiao", db.Column("student_id", db.Integer, db.ForeignKey("student.id")), db.Column("course_id", db.Integer, db.ForeignKey("course.id"))) # #添加数据路由 # @app.route("/many_many/") # def many_many(): # s = Student.query.get(1) # c = Course.query.get(3) # print(s.course) # s.course.append(c) # return "学生"+s.name+"选了"+c.name #查询路由 @app.route("/many_many/<id>/") def many_many(id): # #通过学生查课程 # s = Student.query.get(id) # course = s.course.all() # return ",".join(c.name for c in course) #通过课程找学生 c = Course.query.get(id) #? students = c.students.all() return ",".join(s.name for s in students) if __name__ == '__main__': manager.run()