完成注册功能

js文件： onclick函数return True时才提交表单，return False时不提交表单。
html文件：
1. <form>中设置 action和method="post"
2. <input> 中设置 name
主py文件中：
1. from flask import request, redirect, url_for
2. @app.route('/regist/', methods=['GET', 'POST’])

def regist():

if request.method == 'GET':

return render_template('regist.html')

else:

username = request.form.get(‘username’)#获取form中的数据

判断用户名是否存在:存在报错

不存在，存到数据库中

redirect重定向到登录页

function myLogin() {
            var oUname = document.getElementById("umane");
            var oError = document.getElementById("error_box");
             var oUpass = document.getElementById("upass");
            oError.innerHTML = "<br>"
     //oUname
        if (oUname.value.length>12 || oUname.value.length<6){
            oError.innerHTML = "用户名必须为6到12位数";
            return;
         } else if((oUname.value.charCodeAt(0)>=48) && oUname.value.charCodeAt(0)<=57){
 
            oError.innerHTML = "首字母不能为数字";
            return;
        }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 = "用户名只能包含字母和数字";
                    return;
                }
            }
 
 
            if(upass.value.length>12 || upass.value.length<6){
                oError.innerHTML="密码为6到12位数";
                return;
            }
            window.alert("已成功登陆")

 if(oCheckpass.value!=oUpass.value) {
        oError.innerHTML = "sorry,the password is false";
        return false;

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <link rel="stylesheet" type="text/css" href="../static/css/1234.css">
    <script src="../static/js/123.js"></script>
 
 
</head>
<body>
<form action="{{ url_for('regist') }}" method="post" >
<div class="Outbox">
      <div class="box">
          <h2>欢迎来到博客园，代码改变世界！</h2>
          <h3>登录页面</h3>
 
        <div class="input_box">
           账号：<input id="umane"type="text"placeholder="请输入账号">
        </div>
        <div class="input_box">
           密码：<input id="upass"type="password"placeholder="请输入密码">
        </div>
          <div id="error_box"><br></div>
          <div class="input_box">
              <button onclick="myLogin()">登录</button>
               <button onclick=window.alert("请重新输入")>取消</button></div>
 
          </div>
</div>
 </form>
</body>
</html>

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

import config

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


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(20))
# db.create_all()

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


@app.route('/regist/',methods=['GET','POST'])
def regist():
    if request.method == 'GET':
        return render_template("regist.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) #数据库，添加操作
            db.session.commit()
            return redirect(url_for('login'))


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



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