Flask-SQLAlchemy的使用

Flask-SQLAlchemy的使用

• 1、创建数据库

create  database flask_mysql charset utf8

• 2、配置数据库信息

DIALECT = 'mysql'
DRIVER = 'mysqldb'
USERNAME = 'root'
PASSWORD = 'root'
HOST = '127.0.0.1'
PORT = '3306'
DATABASE = 'flask_sql'
SQLALCHEMY_DATABASE_URI = "{}+{}://{}:{}@{}:{}/{}?charset=utf8".format(DIALECT,DRIVER,USERNAME,PASSWORD,HOST,PORT,DATABASE)
SQLALCHEMY_TRACK_MODIFICATIONS = False

• 3、主文件app配置

app = Flask(__name__)
app.config.from_object(config)
db = SQLAlchemy(app)

• 4、初始化 flask-sqlalchemy

from flask import Flask
import config
from flask_sqlalchemy import  SQLAlchemy

• 5、创建数据库表

app = Flask(__name__)
app.config.from_object(config)
db = SQLAlchemy(app)
class Article(db.Model):
 __tablename__ = 'article'
 id = db.Column(db.Integer,primary_key=True,autoincrement=True)
 # nullable=False 不能为空
title = db.Column(db.String(32),nullable=False)
content = db.Column(db.Text,nullable=False)

• 6、测试数据库是否连接成功 注:程序运行没有报错表示正常的

db.create_all()

from flask import Flask
import config
from flask_sqlalchemy import  SQLAlchemy
app = Flask(__name__)
app.config.from_object(config)
db = SQLAlchemy(app)
class Article(db.Model):
    __tablename__ = 'article'
    id = db.Column(db.Integer,primary_key=True,autoincrement=True)
    # nullable=False 不能为空
    title = db.Column(db.String(32),nullable=False)
    content = db.Column(db.Text,nullable=False)
class User(db.Model):
    __tablename__ = 'users'
    id = db.Column(db.Integer,primary_key=True,autoincrement=True)
    name = db.Column(db.String,nullable=False)
    # nullable=False 不能为空
    title = db.Column(db.String(32),nullable=False)
    content = db.Column(db.Text,nullable=False)
db.drop_all()
db.create_all()
@app.route('/')
def index():
    return 'Hello World'
if __name__ == '__main__':
    app.run(debug=True)

• 7、数据库增删查
• 1)增加

 art = Article(title='aaa',content='bbb')
   db.session.add(art)
   db.session.commit()

• 2)查询

 art = Article.query.filter().first()
    print(art.title)
    print(art.content)

• 3)修改

  art.title = 'ccc'
  db.session.commit()

• 4)删除

db.session.delete(art)
db.session.commit()

• flask-SQLAlchemy外键及其关系
  

Flask数据库迁移操作步骤

• 项目结构
  
• 1、app主文件配置

from flask import Flask,render_template,request
import config


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

@app.route('/')
def index():
    return render_template('index.html')

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

• 2、config文件配置 注:不可变

#encoding: utf-8
import os
DEBUG = True

SECRET_KEY = os.urandom(24)

HOSTNAME = '127.0.0.1'
PORT = '3306'
DATABASE = 'list'
USERNAME = 'root'
PASSWORD = 'root'
DB_URI = 'mysql+mysqldb://{}:{}@{}:{}/{}?charset=utf8'.format(USERNAME,PASSWORD,HOSTNAME,PORT,DATABASE)
SQLALCHEMY_DATABASE_URI = DB_URI
SQLALCHEMY_TRACK_MODIFICATIONS = False

• 3、exts文件配置

# -*- coding: utf-8 -*-
# @Author  : 张江峰
# @Time    : 2018/10/16 11:47
# @E-Mail : jiangfengzh365@163.com
# @File    : exts.py
# @Software: PyCharm
from  flask_sqlalchemy import SQLAlchemy

db = SQLAlchemy()

• 4 、manage文件配置

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

from flask_script import Manager
from flask_migrate import Migrate,MigrateCommand
from exts import db
from apps import app

from models import User

manage = Manager(app)

migrate = Migrate(app,db)


manage.add_command('db',MigrateCommand)



if __name__ == "__main__":
    manage.run()

• 5、models文件配置

# -*- coding: utf-8 -*-
# @Author  : 张江峰
# @Time    : 2018/10/16 11:48
# @E-Mail : jiangfengzh365@163.com
# @File    : models.py
# @Software: PyCharm

from exts import db

class User(db.Model):
    __tablename__ = 'user'
    id = db.Column(db.Integer,primary_key=True,autoincrement=True)
    telephone = db.Column(db.String(11),nullable=False)
    username = db.Column(db.String(100),nullable=False)
    password = db.Column(db.String(100),nullable=False)

flask_migrate相关的命令 (执行数据库迁移)

• 初始化一个迁移脚本的环境，只需要执行一次

python manage.py db init

• 将模型生成迁移文件，只要模型更改了，就需要执行一遍这个命令

python manage.py db migrate

• 将迁移文件真正的映射到数据库中。每次运行了migrate命令后，就记得要运行这个命令

python manage.py db upgrade

装饰器

• 1、装饰器使用是通过@符号，放在函数的上面
• 2、装饰器中定义的函数，要使用 *args,**kwargs 两对兄弟组合\
• 3、为了不改变装饰下函数的——name——属性 需要增加 {from functools import wraps}

from functools import wraps
def my_log(fun):
    @wraps(fun)
    def wrapper(*args,**kwargs):
        print 'hello world'
        fun(*args,**kwargs)
    return wrapper
    
@my_log
def run():
    print 'run'
run()
# 打印函数参数的名字
print run.__name__
@my_log
def add(a ,b):
    c = a+b
    print u'计算结果是 %s' % c