V2AS问路
FLask插件
阅读原文时间：2023年07月09日阅读：4

Flask插件

  • 下载

    pip install Flask-session

  • 导入

    from flask_session import Session

  • 实例化session

    在__init__文件中

    def create_app():
    app = Flask(__name__)
    Session(app)
    return app

  • 配置文件

    SESSION_TYPE = 'redis'

  • 用法和内置session一样

  • 实现原理

    • 内置的session调用 session_interface = xxxx

      • xxxx.open_session 解密cookie转化成字典给session
      • xxxx.save_session 将session加密给cookie

    • Flask-session 修改session_interface 制定的类

      • 来改变session存储的位置

创建连接

from sqlalchemy import create_engine
conn = create_engine(
    # 'mysql+pymysql://rout用户:密码@连接地址:端口号/数据库名?charset=编码方式'
    'mysql+pymysql://root:123@127.0.0.1:3306/day103?charset=ustf8',
    max_overflow = 0,   # 超过连接池大小外最多创建的连接数
    pool_size = 5,    # 连接池大小
    pool_timeout=30,    # 连接池中没有线程最多等待时间,否则报错
    pool_recycle=-1,    # 多久之后对连接池中的连接进行回收(重置), -1不回收

)

如何创建表

  • 导入

    from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()

  • 单表创建

    class Book(Base):
   __tablename__ = "book"

   id = Column(Integer, primary_key=True)
   title = Column(String(32), nullable=False，index=True)

   def __repr__(self):
      return self.title

   __table_args__ = (
      # 联合唯一
      UniqueConstraint("id", "title", name="uni_id_title"),
      # 联合索引
      Index("id", "title")
   )


from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, DateTime
from sqlalchemy import Index, UniqueConstraint
import datetime
# 连接数据库
ENGINE = create_engine("mysql+pymysql://root:root1234@127.0.0.1:3306/code_record?charset=utf8",)
# 实例化
Base = declarative_base()

# 创建单表,继承Base
class UserInfo(Base):
    __tablename__ = "user_info"
    id = Column(Integer, primary_key=True)
name = Column(String(32), index=True, nullable=False)
email = Column(String(32), unique=True)
create_time = Column(DateTime, default=datetime.datetime.now)
    # 类似与django中的class Meta, 针对于本表
    __table_args__ = (
        # 设置联合唯一
        UniqueConstraint("id", "name", name="uni_id_name"),
        # 设置联合索引
        Index("name", "email")
    )

# 函数,方便创建表
def create_db():
    Base.metadata.create_all(ENGINE)

# 方便删除
def drop_db():
    Base.metadata.drop_all(ENGINE)

if __name__ == '__main__':
    # 执行
    create_db()

  • 一对多表创建

    class Book(Base):
   __tablename__ = "book"

   id = Column(Integer, primary_key=True)
   title = Column(String(32), nullable=False)
   publisher_id = Column(Integer, ForeignKey("publisher.id"))
   # 不生成字段建立关系 方便操作
   # 一对多
   publisher = relationship("Publisher", backref="books")


from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, DateTime
from sqlalchemy import Index, UniqueConstraint, ForeignKey
from sqlalchemy.orm import relationship
import datetime

ENGINE = create_engine("mysql+pymysql://root:root1234@127.0.0.1:3306/code_record?charset=utf8",)

Base = declarative_base()

# ======一对多示例=======
class UserInfo(Base):
    __tablename__ = "user_info"
    id = Column(Integer, primary_key=True)
name = Column(String(32), index=True, nullable=False)
email = Column(String(32), unique=True)
create_time = Column(DateTime, default=datetime.datetime.now)
# FK字段的建立
hobby_id = Column(Integer, ForeignKey("hobby.id"))
# 不生成表结构 方便查询使用
hobby = relationship("Hobby", backref="user")

__table_args__ = (
    UniqueConstraint("id", "name", name="uni_id_name"),
    Index("name", "email")
)
    class Hobby(Base):
    __tablename__ = "hobby"
    id = Column(Integer, primary_key=True)
title = Column(String(32), default="码代码")
    def create_db():
    Base.metadata.create_all(ENGINE)

def drop_db():
    Base.metadata.drop_all(ENGINE)

if __name__ == '__main__':
    create_db()
    # drop_db()

  • 多对对创建

    • 第三张表自己生成

      class Book(Base):
   __tablename__ = "book"

   id = Column(Integer, primary_key=True)
   title = Column(String(32), nullable=False)
   publisher_id = Column(Integer, ForeignKey("publisher.id"))
   # 不生成字段建立关系 方便操作
   # 一对多
   publisher = relationship("Publisher", backref="books")
   # 多对多
   tags = relationship("Tag", secondary="book2tag", backref="books")
class Book2Tag(Base):
   __tablename__ = "book2tag"

   id = Column(Integer, primary_key=True)
   book_id = Column(Integer, ForeignKey("book.id"))
   tag_id = Column(Integer, ForeignKey("tag.id"))


from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, DateTime
from sqlalchemy import Index, UniqueConstraint, ForeignKey
from sqlalchemy.orm import relationship
import datetime

ENGINE = create_engine("mysql+pymysql://root:root1234@127.0.0.1:3306/code_record?charset=utf8",)

Base = declarative_base()

# ======多对多示例=======
class Book(Base):
    __tablename__ = "book"
      id = Column(Integer, primary_key=True)
title = Column(String(32))
# 不生成表字段 仅用于查询方便
tags = relationship("Tag", secondary="book2tag", backref="books")
      class Tag(Base):
    __tablename__ = "tag"
      id = Column(Integer, primary_key=True)
title = Column(String(32))
      class Book2Tag(Base):
    __tablename__ = "book2tag"
      id = Column(Integer, primary_key=True)
book_id = Column(Integer, ForeignKey("book.id"))
tag_id = Column(Integer, ForeignKey("tag.id"))
      def create_db():
    Base.metadata.create_all(ENGINE)

def drop_db():
    Base.metadata.drop_all(ENGINE)

if __name__ == '__main__':
    create_db()
    # drop_db()

    • 创建表命令

      Base.metadata.create_all(conn) # conn是连接池对象

对数据库表的操作(增删改查)

  • 创建管理器

    from sqlalchemy.orm import sessionmaker, scoped_session
Session = sessionmaker(bind=conn)
# 线程安全 根本本地线程会使用一个session
session = scoped_session(Session)


from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker, scoped_session
from models_demo import Tag

ENGINE = create_engine("mysql+pymysql://root:root1234@127.0.0.1:3306/code_record?charset=utf8",)

Session = sessionmaker(bind=ENGINE)

# 每次执行数据库操作的时候，都需要创建一个session

# 线程安全，基于本地线程实现每个线程用同一个session

session = scoped_session(Session)

# =======执行ORM操作==========
tag_obj = Tag(title="SQLAlchemy")
# 添加
session.add(tag_obj)
# 提交
session.commit()
# 关闭session
session.close()

  • 基本增删改查

    from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker, scoped_session
from models_demo import Tag, UserInfo
import threading

ENGINE = create_engine("mysql+pymysql://root:root1234@127.0.0.1:3306/code_record?charset=utf8",)

Session = sessionmaker(bind=ENGINE)

# 每次执行数据库操作的时候，都需要创建一个session
session = Session()
session = scoped_session(Session)

# ============添加============
# tag_obj = Tag(title="SQLAlchemy")
# # 添加
# session.add(tag_obj)
# session.add_all([
#     Tag(title="Python"),
#     Tag(title="Django"),
# ])
# # 提交
# session.commit()
# # 关闭session
# session.close()

# ============基础查询============
# ret1 = session.query(Tag).all()
# ret2 = session.query(Tag).filter(Tag.title == "Python").all()
# ret3 = session.query(Tag).filter_by(title="Python").all()
# ret4 = session.query(Tag).filter_by(title="Python").first()
# print(ret1, ret2, ret3, ret4)

# ============删除===========
# session.query(Tag).filter_by(id=1).delete()
# session.commit()

# ===========修改===========
session.query(Tag).filter_by(id=22).update({Tag.title: "LOL"})
session.query(Tag).filter_by(id=23).update({"title": "王者毒药"})
session.query(Tag).filter_by(id=24).update({"title": Tag.title + "~"}, synchronize_session=False)
# synchronize_session="evaluate" 默认值进行数字加减
session.commit()

  • 常用操作

    # 条件查询
ret1 = session.query(Tag).filter_by(id=22).first()
ret2 = session.query(Tag).filter(Tag.id > 1, Tag.title == "LOL").all()
ret3 = session.query(Tag).filter(Tag.id.between(22, 24)).all()
ret4 = session.query(Tag).filter(~Tag.id.in_([22, 24])).first()
from sqlalchemy import and_, or_
ret5 = session.query(Tag).filter(and_(Tag.id > 1, Tag.title == "LOL")).first()
ret6 = session.query(Tag).filter(or_(Tag.id > 1, Tag.title == "LOL")).first()
ret7 = session.query(Tag).filter(or_(
    Tag.id>1,
    and_(Tag.id>3, Tag.title=="LOL")
)).all()
# 通配符
ret8 = session.query(Tag).filter(Tag.title.like("L%")).all()
ret9 = session.query(Tag).filter(~Tag.title.like("L%")).all()
# 限制
ret10 = session.query(Tag).filter(~Tag.title.like("L%")).all()[1:2]
# 排序
ret11 = session.query(Tag).order_by(Tag.id.desc()).all()  # 倒序
ret12 = session.query(Tag).order_by(Tag.id.asc()).all()  # 正序
# 分组
ret13 = session.query(Tag.test).group_by(Tag.test).all()
# 聚合函数
from sqlalchemy.sql import func
ret14 = session.query(
    func.max(Tag.id),
    func.sum(Tag.test),
    func.min(Tag.id)
).group_by(Tag.title).having(func.max(Tag.id > 22)).all()
# 连表
ret15 = session.query(UserInfo, Hobby).filter(UserInfo.hobby_id == Hobby.id).all()
# print(ret15) 得到一个列表套元组 元组里是两个对象
ret16 = session.query(UserInfo).join(Hobby).all()
# print(ret16) 得到列表里面是前一个对象
# 相当于inner join
# for i in ret16:
#     # print(i[0].name, i[1].title)
#     print(i.hobby.title)
ret17 = session.query(Hobby).join(UserInfo, isouter=True).all()
ret17_1 = session.query(UserInfo).join(Hobby, isouter=True).all()
ret18 = session.query(Hobby).outerjoin(UserInfo).all()
ret18_1 = session.query(UserInfo).outerjoin(Hobby).all()
# 相当于left join
print(ret17)
print(ret17_1)
print(ret18)
print(ret18_1)

  • 基于relationship的Fk

    # 基于relationship的FK
# 添加
user_obj = UserInfo(name="提莫", hobby=Hobby(title="种蘑菇"))
session.add(user_obj)

hobby = Hobby(title="弹奏一曲")
hobby.user = [UserInfo(name="琴女"), UserInfo(name="妹纸")]
session.add(hobby)
session.commit()

# 基于relationship的正向查询
user_obj_1 = session.query(UserInfo).first()
print(user_obj_1.name)
print(user_obj_1.hobby.title)

# 基于relationship的反向查询
hb = session.query(Hobby).first()
print(hb.title)
for i in hb.user:
    print(i.name)

session.close()

  • 基于relationship的M2M

    # 添加
book_obj = Book(title="Python源码剖析")
tag_obj = Tag(title="Python")
b2t = Book2Tag(book_id=book_obj.id, tag_id=tag_obj.id)
session.add_all([
    book_obj,
    tag_obj,
    b2t,
])
session.commit()

#  上面有坑哦~~~~
book = Book(title="测试")
book.tags = [Tag(title="测试标签1"), Tag(title="测试标签2")]
session.add(book)
session.commit()

tag = Tag(title="LOL")
tag.books = [Book(title="大龙刷新时间"), Book(title="小龙刷新时间")]
session.add(tag)
session.commit()

# 基于relationship的正向查询
book_obj = session.query(Book).filter_by(id=4).first()
print(book_obj.title)
print(book_obj.tags)
# 基于relationship的反向查询
tag_obj = session.query(Tag).first()
print(tag_obj.title)
print(tag_obj.books)

  • 下载

    pip install flask-script

  • 导入

    from flask_demo import create_app
from flask_script import Manager

  • 实例化

    app = create_app()
# 实例化
manager = Manager(app)

if __name__ == '__main__':
   # app.run()
   manager.run()

  • 自定义的命令

  • !!! 依赖flask-script

  • 下载

    pip install flask-migrate

  • 导入

    from flask_Migrate import Migrate, MigrateCommand

  • 实例化

    Migrate(app)

manager.add_command('db', MigrateCommand)
"""
    python manager.py db init
    python manager.py db migrate # 类型于makemigrations
    python manager.py db uprade  # migrate
"""
师博客:

https://www.cnblogs.com/GGGG-XXXX/articles/9447619.html

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