完成注册功能

1. js文件： onclick函数return True时才提交表单，return False时不提交表单。
2. html文件：
   1. <form>中设置 action和method="post"
   2. <input> 中设置 name
3. 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

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

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()
# user=User(username='mis1',password='11111')
# db.session.add(user)
# db.session.commit()

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

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



@app.route('/regist/',methods=['GET','POST'])
def regist():
    if request.method=='GET':
        return render_template('regist.html')
    else:
        usern=request.form.get('username')
        passw=request.form.get('password')
        nickn=request.form.get('nickname')
        user=User.query.filter(User.username==usern).first()
        if user:
            return u'username existed'
        else:
            user=User (username=usern,password=passw,nickname=nickn)
            db.session.add(user)
            db.session.commit()
            return redirect(url_for('login'))



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

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

{% extends 'base.html' %}
{% block title %}
    注册
{% endblock %}

{% block head %}

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

{% block main %}

    <div class="login">

          <h1>注册</h1>

<form action="{{ url_for('regist') }}" method="post">

        <p><input id="unane"type="text" name="username" placeholder="请输入账户"></p>
        <p><input id="unane1"type="text" name="nickname" placeholder="请输入昵称"></p>

        <p><input id="upass" type="password" name="password" placeholder="请输入密码"></p>
       <p><input id="upass1" type="password" placeholder="请再次输入密码"></p>
          <div id="error_box"><br></div>
<p class="submit">

    <input  onclick="return myLogin()" type="submit" name="commit" value="注册">
     <input  onclick=window.alert("是否取消注册？") type="submit" name="commit" value="取消">
</p>
</form>
    </div>


</div>


</body>
{% endblock %}

function myLogin() {
            var oUname = document.getElementById("unane");
            var oUname1 = document.getElementById("unane1");
             var oError = document.getElementById("error_box");
             var oUpass = document.getElementById("upass");
             var  oUpass1= document.getElementById("upass1");

            oError.innerHTML = "<br>"
     //oUname
        if (oUname.value.length>12 || oUname.value.length<6){
            oError.innerHTML = "name:6-12";
          return false;

         } else if((oUname.value.charCodeAt(0)>=48) && oUname.value.charCodeAt(0)<=57){

            oError.innerHTML = "首字母不能是数字";
          return false;

        }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 = "只能包含字母和数字";
                    return false;
                }
            }


            if(upass.value.length>12 || upass.value.length<6){
                oError.innerHTML="password;6-12";
               return false;
            }
            if(oUpass.value != oUpass1.value){
                oError.innerHTML="两次密码输入不一致";
            return false;
            }

             window.alert("注册成功 ！")
              return true;

        }