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Python编程:Flask数据库扩展Flask-SQLAlchemy


英文文档:​​​http://flask-sqlalchemy.pocoo.org/2.3/​​​

中文文档:​​​http://www.pythondoc.com/flask-sqlalchemy/quickstart.html​​​

安装

pip install flask-sqlalchemy
pip install flask-mysqldb

flask-sqlalchemy

模型类 -> sql
数据库结果 -> 模型类

数据库驱动

# python3
pip install pymysql
pymysql.install_as_MySQLdb()

# python2
pip install MySQL-Python

数据库设置

# 1、数据库连接
app.config["SQLALCHEMY_DATABASE_URI"] = "msyql://root:123456@127.0.0.1:3306/db_name"

# 2、自动提交(不推荐)
app.config["SQLALCHEMY_COMMIT_ON_TEARDOWN"] = True

# 3、修改自动跟踪
app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = True

# 4、显示原始SQL
app.config["SQLALCHEMY_ECHO"] = True

代码示例

# -*- coding: utf-8 -*-

from flask import Flask
from flask_sqlalchemy import SQLAlchemy


# 配置参数
class Config(object):
SQLALCHEMY_DATABASE_URI = "mysql://root:123456@127.0.0.1:3306/demo"
SQLALCHEMY_TRACK_MODIFICATIONS = True
# SQLALCHEMY_ECHO = True


app = Flask(__name__)
app.config.from_object(Config)

db = SQLAlchemy(app)


# 创建数据库模型类
class Role(db.Model):
"""用户角色"""
__tablename__ = "tbl_roles"

id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(32), unique=True)

users = db.relationship("User", backref="role")

def __repr__(self):
return "<Role name: {}>".format(self.name)


class User(db.Model):
"""用户表"""
__tablename__ = "tbl_users" # 表名

id = db.Column(db.Integer, primary_key=True) # 整型主键默认自增
name = db.Column(db.String(64), unique=True)
email = db.Column(db.String(128), unique=True)
password = db.Column(db.String(128))
role_id = db.Column(db.Integer, db.ForeignKey("tbl_roles.id"))

def __repr__(self):
return "<User name: {}>".format(self.name)


if __name__ == '__main__':
# 删除表
db.drop_all()

# 创建表
db.create_all()

创建数据

# 1、创建一条数据
role1 = Role(name="admin")
role2 = Role(name="stuff")
db.session.add(role1)
db.session.add(role2)
db.session.commit()

# 2、 一次保存多个数据
user1 = User(name="张三", email="123@qq.com", password="123456", role_id=role1.id)
user2 = User(name="李四", email="456@qq.com", password="12345x", role_id=role2.id)
user3 = User(name="王五", email="339@qq.com", password="12345y", role_id=role1.id)
user4 = User(name="刘能", email="226@qq.com", password="12345v", role_id=role2.id)
user5 = User(name="赵四", email="778@qq.com", password="12345b", role_id=role1.id)

db.session.add_all([user1, user2, user3, user4, user5])
db.session.commit()

查询数据

# 1、简单查询
rows = Role.query.all()
row = Role.query.first()
row = Role.query.get(<id>)

rows = db.seesion.query(Role).all()
row = db.seesion.query(Role).first()
row = db.seesion.query(Role).get(<id>)

# 2、条件过滤(与关系)
row = Role.query.filter(Role.name="张三", Role.role_id=2).first()

row = Role.query.filter_by(name="张三", role_id=2).first()

# 3、模糊查询(或关系)
from sqlalchemy import or_
row = Role.query.filter(or_(Role.name.startswith("张"), Role.role_id=2)).first()

# 4、分页
rows = Role.query.offset(2).limit(10).all()

# 5、排序
rows = Role.query.order_by("-id").all()

rows = Role.query.order_by(Role.id.desc()).all()

# 6、分组
from sqlalchemy import func
rows = db.session.query(Role.id, func.count(Role.id)).group_by(Role.id)

# 7、外键查询
user = User.query.get(1)
user.role.name

role = Role.query.get(1)
role.users

更新数据

# 1、更新对象
user = User.query.get(1)
user.name = "python"
db.session.add(user)
db.session.commit()

# 2、直接更新数据
User.query.filter_by(name="张三").update({"name": "python"})
db.session.commit()

删除数据

user = User.query.get(1)
db.session.delete(user)
db.session.commit()

​注意​​ 更新和删除操作先进行查询校验where条件



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