sqlalchemy的ORM排序

from sqlalchemy import create_engine, Column, Integer, String, DateTime, Float, func, and_, or_, ForeignKey, Table

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker, relationship, backref
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)()


# 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)


# 文章
class Article(Base):
    # 表名字
    __tablename__ = 'article'
    # 列
    id = Column(Integer, primary_key=True, autoincrement=True)
    title = Column(String(50))
    # 设置外键
    uid = Column(Integer, ForeignKey('User.id', ondelete="RESTRICT"))
    create_time = Column(DateTime, default=datetime.now)
    update_time = Column(DateTime, onupdate=datetime.now, default=datetime.now)
    author = relationship("User", backref=backref("articles",
                                                  order_by=create_time.desc()))
    __mapper__args__ = {
        "order_by": create_time.desc
    }

    def __repr__(self):
        return "<Article(title:%s)>" % self.title


# 生成实体
# Base.metadata.drop_all()
# Base.metadata.create_all()
# import time
# user = User(username="ceshi001")
# article1 = Article(title="title0001")
# article2 = Article(title="title0002")
# article3 = Article(title="title0003")
# article4 = Article(title="title0004")
# user.articles.append(article1)
# session.add(article1)
# time.sleep(2)
# user.articles.append(article2)
# session.add(article2)
# time.sleep(2)
# user.articles.append(article3)
# session.add(article3)
# time.sleep(2)
# time.sleep(2)
# user.articles.append(article4)
# session.add(article4)
# session.commit()

user = session.query(User).first()
print(user.articles)
# order_by排序
# article = session.query(Article).order_by(Article.create_time.desc()).all()
# print(article)
# article = session.query(Article).order_by("create_time").all()
# print(article)
#
# article = session.query(Article).all()
# print(article)

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