flask扩展模块flask-sqlachemy 的使用---mysql数据库

该篇博客配置环境为:python版本3.5，flask2.0，python3中已经不再支持MySQLdb模块，所有这里我用了pymysql，所有使用前应该

安装pymysql:pip install pymysql

在网上的好多资料都给的是使用sqlite的例子，由于很不喜欢所以今天分享一下flask-sqlalchemy操作mysql的方法.

以前习惯使用sqlalchemy,后来发现使用flask-sqlchemy还是要简单一些（起码省去了好多模块和类的导入，create_engine,sessionmaker,declarative。。。）不过flask官方的例子用的是sqlchemy，去官网, flask-sqlalchemy官方文档

　　这里写一个简单的flask web程序，来说明flask-sqlalchemy如何驱动msyql数据库.为了偷懒，这个例子以上一篇博文flask蓝图的使用为基础.

首先看一下程序结构:

相比上一节只多了两个文件，create_db.py,models.py

1.建立mysql和app的连接

在config.py中加入以下两项配置:

SQLALCHEMY_DATABASE_URI = 'mysql+pymysql://root:xxxxx@localhost:3306/test?charset=utf8'
SQLALCHEMY_TRACK_MODIFICATIONS = True

如此在app/__init__.py中加入
app.config.from_object('config')

db = SQLAlchemy(app)

就可以完成app和数据的关联，并生成一个可以操作app数据库的SQLAlchemy实例db

完整的app/__init__.py代码如下:

from flask import Flask, url_for, request, redirect, render_template
from flask_sqlalchemy import SQLAlchemy
app = Flask(__name__)
app.config.from_object('config')
db = SQLAlchemy(app)
from app import models,views

2.创建app/models.py模块

上代码

from app import db #db是在app/__init__.py生成的关联后的SQLAlchemy实例

class User(db.Model):
    __tablename__ = 'users'
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(80), unique=True)
    email = db.Column(db.String(320), unique=True)
    password = db.Column(db.String(32), nullable=False)

    def __repr__(self):
        return '<User %r>' % self.username

class Admin(db.Model):
    __tablename__ = 'admins'
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(80), unique=True)
    email = db.Column(db.String(320), unique=True)
    password = db.Column(db.String(32), nullable=False)

    def __repr__(self):
        return '<User %r>' % self.username

3.创建create_db.py，表结构设计完成后执行python create_db.py即可完成表的创建,如下图

#app/create_db.py

from app import db
db.create_all()

4.表已经创建完成了，接下来是我们的业务逻辑使用表的时候了

分别在user和admin蓝图中增加一个add用户的业务

#app/user.py

from flask import Blueprint, render_template, redirect,request
from app import db
from .models import User
user = Blueprint('user',__name__)

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

@user.route('/add/',methods=['GET','POST'])
def add():
    if request.method == 'POST':
        p_user = request.form.get('username',None)
        p_email = request.form.get('email',None)
        p_password = request.form.get('password',None)

        if not p_user or not p_email or not p_password:
            return 'input error'

        newobj = User(username=p_user, email=p_email, password=p_password)
        db.session.add(newobj)
        db.session.commit()
        users = User.query.all()
        return render_template('user/add.html',users=users)
    users = User.query.all()
    return render_template('user/add.html',users=users)

@user.route('/show')
def show():
    return 'user_show'

#app/admin.py

#admin.py
from flask import Blueprint,render_template, request, redirect
from app import db
from .models import Admin

admin = Blueprint('admin',__name__)

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

@admin.route('/add/',methods=['POST','GET'])
def add():
    if request.method == 'POST':
        p_admin = request.form.get('username',None)
        p_email = request.form.get('email',None)
        p_password = request.form.get('password',None)

        if not p_admin or not p_email or not p_password:
            return 'input error'

        newobj = Admin(username=p_admin, email=p_email, password=p_password)
        db.session.add(newobj)
        db.session.commit()
        admins = Admin.query.all()
        return render_template('admin/add.html',admins=admins)
    admins = Admin.query.all()
    return render_template('admin/add.html',admins=admins)

@admin.route('/show')
def show():
    return 'admin_show'

#app/templates/admin/add.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>AdminsAdd</title>
</head>
<body>
<form action="/admin/add/" method="POST">
    user:<input type="text" name="username" />
    email:<input type="text" name="email" />
    pwd:<input type="password" name="password" />
    <input type="submit" value="add" />
</form>
{% if admins %}
<table border="1px">
    <tr>
        <th>UserName</th>
        <th>Email</th>
    </tr>
    {% for u in admins %}
        <tr>
            <td>{{u.username}}</td>
            <td>{{u.email}}</td>
        </tr>
    {% endfor %}
</table>
{% endif %}
</body>
</html>

#app/templates/user/add.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>UserAdd</title>
</head>
<body>
<form action="/user/add/" method="POST">
    user:<input type="text" name="username" />
    email:<input type="text" name="email" />
    pwd:<input type="password" name="password" />
    <input type="submit" value="add" />
</form>
{% if users %}
<table border="1px">
    <tr>
        <th>UserName</th>
        <th>Email</th>
    </tr>
    {% for u in users %}
        <tr>
            <td>{{u.username}}</td>
            <td>{{u.email}}</td>
        </tr>
    {% endfor %}
</table>
{% endif %}
</body>
</html>

#app/views.py

from app import app
from .admin import admin
from .user import user

app.register_blueprint(admin,url_prefix='/admin')
app.register_blueprint(user, url_prefix='/user')

#run.py

from app import app
app.run()

到这里也就结束了，这样这个例子就结合了蓝图和flask-sqlalchemy.本例中只使用了db.session.add(),其它的还有db.session.delete()...

看一下效果:

localhost:5000/user/add

localhost:5000/admin/add