完成登录功能，用session记住用户名

登录功能完成：

1. js:设置return

   function fnLogin() {
   var oUname=document.getElementById("uname");
   var oUpass=document.getElementById("upass");
   var oError=document.getElementById("error_box");
   var isError=true;
   oError.innerHTML="<br>"

   //uname
   if ((oUname.value.length < 6) || (oUname.value.length > 20)) {
   oError.innerHTML = "用户名要6-20位";
   isError=false;
   return isError;
   }else if ((oUname.value.charCodeAt(0)>=48)&&(oUname.value.charCodeAt(0)<=57)){
   oError.innerHTML="首字母必须是字母";
   isError=false;
   return isError;
   }else {
   for(var i=0;i<oUname.value.length;i++){
   if ((oUname.value.charCodeAt(i)<48)||(oUname.value.charCodeAt(i)>57)&&(oUname.value.charCodeAt(i)<97) ||(oUname.value.charCodeAt(i)>122)){
   oError.innerHTML="用户名只能是字母和数字";
   isNotError=false;
   return isError;
   }
   }
   }
   //upass
   if ((oUpass.value.length < 6 )|| (oUpass.value.length > 20)) {
   oError.innerHTML = "密码要6-20位";
   isError=false;
   return isError;
   }
   return isError;
   window.alert("登录成功！")
   }

    

2. html:设置
   1. form
   2. input

   3. onclick="return fnLogin()"

      {% extends‘base.html‘ %}
      {% block title %}登录{% endblock %}
      {% block head %}
      <link rel="stylesheet" type="text/css" href="{{ url_for(‘static‘,filename=‘css/login.css‘) }}">
      <script src="{{ url_for(‘static‘,filename=‘/js/login.js‘)}}"></script>
      {% endblock %}

      {% block main %}

      <div class="box">
      <h2>登录</h2>
      <form action="{{ url_for(‘login‘) }}" method="post">
      <div class="input_box">
      <input id="uname" type="text"placeholder="请输入用户名" name="username">
      <input id="unickname" type="text"placeholder="请输入昵称" name="nickname">
      </div>

      <div class="input_box">
      <input id="upass" type="password"placeholder="请输入密码" name="password">
      </div>

      <div class="input_box">
      <a href="{{ url_for(‘enroll‘) }}">没有账号？立即注册</a>
      </div>

      <div id="error_box"><br></div>
      <div class="input_box">
      <button class="button" onclick="fnLogin()">登录</button>
      </div>
      </form>
      </div>
      {% endblock %}

       

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。

               from flask import Flask, render_template, request, redirect, url_for, session
               from flask_sqlalchemy import SQLAlchemy
               import config
               
               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)
                   nickname=db.Column(db.String(50))
               
               # db.create_all()
               # 首页
               @app.route(‘/‘)
               def index():
                   return render_template(‘base.html‘)
               
               #登录
               @app.route(‘/login/‘,methods={‘GET‘,‘POST‘})
               def login():
                   if request.method==‘GET‘:
                       return render_template(‘login.html‘)
                   else:
                       username = request.form.get(‘username‘)  # 获取form中的数据
                       password = request.form.get(‘password‘)
                       nickname = request.form.get(‘nickname‘)
                       user = User.query.filter(User.username == username).first()
                       if user:
                           if user.password==password:
                               session[‘user‘] = username
                               session.permanent=True
                               return redirect(url_for(‘index‘))  # 返回到首页
                       else:
                           return u‘error username or password‘ #输出错误
               
               
               #注册
               @app.route(‘/enroll/‘,methods={‘GET‘,‘POST‘})
               def enroll():
                   if request.method==‘GET‘:
                       return render_template(‘enroll.html‘)
                   else:
                       username=request.form.get(‘username‘)# 获取form中的数据
                       password=request.form.get(‘password‘)
                       nickname=request.form.get(‘nickname‘)
                       user = User.query.filter(User.username == username).first()
                       if user:
                           return u‘username existed‘
                       else:
                           user = User(username=username, password=password, nickname=nickname)
                           db.session.add(user)#数据库操作
                           db.session.commit()
                           return redirect(url_for(‘login‘))# 重定向到登录页
               
               
                #提问
               @app.route(‘/questions/‘)
               def questions():
                   return render_template(‘questions.html‘)
               
               
               if __name__ == ‘__main__‘:
                   app.run(debug=True)

                

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
   SECRET_KEY = os.urandom(24)
   
   
   SQLALCHEMY_DATABASE_URI = ‘mysql+pymysql://root:@127.0.0.1:3306/mis_db?charset=utf8‘
   SQLALCHEMY_TRACK_MODIFICATIONS = False