sqlalchemy的一对多关系数据查询

from flask import Flask, jsonify, json
from sqlalchemy import create_engine, Column, Integer, String, DateTime, Float, func, and_, or_, ForeignKey

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker, relationship
from datetime import datetime


# 连接数据库字符串
DB_URI = "mysql://root:123456@127.0.0.1/pyDemo?charset=utf8mb4"

engine = create_engine(DB_URI)
# 判断是否连接成功
engine.connect()


# 创建ORM
Base = declarative_base(engine)

# 创建回话
session = sessionmaker(engine)()


# 父 表/从表
# user/Article
# 用户
class User(Base):
    # 表名字
    __tablename__ = 'User'
    # 列
    id = Column(Integer, primary_key=True, autoincrement=True)
    username = Column(String(50), nullable=False)
    # articles = relationship('Article')


# 文章
class Article(Base):
    # 表名字
    __tablename__ = 'article'
    # 列
    id = Column(Integer, primary_key=True, autoincrement=True)
    title = Column(String(50), default='1111')
    content = Column(String(50))
    # 设置外键
    uid = Column(Integer, ForeignKey('User.id', ondelete="RESTRICT"))
    #  取得外键User数据 backref反向定义
    author = relationship('User', backref='articles')

# 一对多关系数据查询
# 查找文章的作者 多篇文章对应一个人
article = session.query(Article).first()
print(article.author.username)
# 查找一个用户下的多个文章信息
users = session.query(User).first()
print(users.articles)

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