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:[email protected]/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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