完成登录功能，用session记住用户名

登录功能完成：

1. js:设置return
2. html:设置
   1. form
   2. input

   3. onclick="return fnLogin()"

3. py:
   1. @app.route设置methods
   2. GET
   3. POST
      1. 读取表单数据
      2. 查询数据库
         1. 用户名密码对：
            1. 记住用户名
            2. 跳转到首页
         2. 用户名密码不对：
            1. 提示相应错误。

session：

1. 从`flask`中导入`session`
2. 设置`SECRET_KEY`
3. 操作字典一样操作`session`：增加用户名`session['username']=`username

import os

SQLALCHEMY_DATABASE_URI = 'mysql+pymysql://root:@localhost:3306/mis_db?charset=utf8'
SQLALCHEMY_TRACK_MODIFICATIONS = False

SECRET_KEY = os.urandom(24)

 

import config
from flask import Flask,render_template,request,redirect,url_for,session
from flask_sqlalchemy import SQLAlchemy

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

#创建用户模型
class User(db.Model):
    __tablename__ = 'User'
    id = db.Column(db.Integer,primary_key=True,autoincrement=True)
    username = db.Column(db.String(20),nullable=False)
    password = db.Column(db.String(20),nullable=False)

#db.create_all()


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

@app.route('/sign_up/',methods=['GET','POST'])#登录
def sign_up():
    if request.method == "GET":
        return render_template("sign_up.html")
    else:
        username = request.form.get("username")
        password = request.form.get("password")
        user = User.query.filter(User.username == username).first()
        if user:
            if user.password == password:
                session['User'] = username
                return redirect(url_for('first'))
            else:
                return u'password error'
        else:
           return u'username is not existed'


@app.route('/sign_in/',methods=['GET','POST'])#注册
def sign_in():
    if request.method == "GET":
        return render_template("sign_in.html")
    else:
        username = request.form.get("username")
        password = request.form.get("password")
        user = User.query.filter(User.username == username).first()
        if user:
            return 'username existed.'
        else:
            user = User(username=username, password=password)
            db.session.add(user)
            db.session.commit()
            return redirect(url_for('sign_up'))

@app.context_processor
def mycontext():
    username=session.get('User')
    if username:
        return {'User':username}
    else:
        return {}

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


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

 

{% extends 'first.html' %}
{% block title %}登录*{% endblock %}

{% block head %}
    <link href="{{url_for('static',filename='css/sign.css') }}" rel="stylesheet" type="text/css">
    <script src="{{ url_for('static',filename='js/sign.js') }}"></script>
{% endblock %}

{% block main %}
    <div class="box">
        <h3>欢迎登陆</h3>
        <form action="{{ url_for('sign_up') }}" method="post">
            <div class="input_box">
               用户名： <input id="uname" type="text" placeholder="请输入用户名" class="b1">
        </div>
             <div class="input_box">
                密码： <input id="upass" type="password" placeholder="请输入密码" class="b1">
             </div>
        <div id="error_box" class="error_box"><br></div>
        <div class="button">
            <button  class="login" onclick="fnLogin()">登录</button>
            <button  class="cancel" onclick=window.alert("是否确认离开，您输入的数据可能不会被保存")>取消</button></div>

    </div>
{% endblock %}