登录功能完成：

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

function fndenglu() {    var oUname = document.getElementById("uname");    var oUpass = document.getElementById("upass");    var oError = document.getElementById("error_box");    var isError = true;    oError.innerHTML = "
";    // oUname    if (oUname.value.length < 6 || oUname.value.length > 20) {        oError.innerHTML = "用户名要6-20之位";        isError = false;        return isError;    } else if ((oUname.value.charCodeAt(0) >= 48) && (oUname.value.charCodeAt(0) <= 57)) {        oError.innerHTML = "首字母不能为数字";        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 = "只能填写数字或字母";            isNotError = false;            return isError;        }    }// oUpass    if (oUpass.value.length > 20 || oUpass.value.length < 6) {        oError.innerHTML = "密码要6-20位";        isError = false;        return isError;    }    return isError;    window.alert("登录成功！")}

 

{% extends 'daohang.html' %}{% block title %}登录{% endblock %}{% block head %}    
         {% endblock %}{% block main %}    
     
        
      
登录
        
      
            
       
                
                    
       
            
       
                
                    
       
            
       
        
       
            
       
                
        登录            
       
        
      
    
     
{% endblock %}

 

@app.route('/denglu/', methods=['GET', 'POST'])def denglu():    if request.method == 'GET':        return render_template('denglu.html')    else:        username = request.form.get('username')        password = request.form.get('password')        user = User.query.filter(User.username == username,User.password==password).first()        if user:            session['user']=username            session.permanent=True            return redirect(url_for('daohang'))        else:            return 'error username or password'

import osDEBUG=TrueSECRET_KEY=os.urandom(24)DIALECT='mysql'DRIVER='mysqldb'USERNAME='root'PASSWORD=''HOST='127.0.0.1'PORT='3306'DATABASE='test'SQLALCHEMY_DATABASE_URI = 'mysql+pymysql://root:@127.0.0.1:3306/test?charset=utf8'SQLALCHEMY_TRACK_MODIFICATIONS = False