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

主py：

from flask import Flask,redirect,request,url_for
from flask import render_template
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()
#查询
# user=User.query.filter(User.username=='mis1234').first()
# print(user.id,user.username,user.password)

#增加
# user=User(username='mis1234',password='111111',nickname='l')
# db.session.add(user)
# db.session.commit()

#增加
# user=User(username='luk',password='123456',nickname='lu')
# db.session.add(user)
# db.session.commit()
# 修改
# user=User.query.filter(User.username=='mis1234').first()
# user.password='12345678'
# db.session.commit()
#
# # 删除
# user=User.query.filter(User.username=='mis1234').first()
# db.session.delete(user)
# db.session.commit()


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


@app.route('/login/',methods=['GET','POST'])
def login():
    return render_template('login.html')


@app.route('/register/',methods=['GET','POST'])
def register():
    if request.method=='GET':
        return render_template('register.html')
    else:
        usern=request.form.get('username')
        nickn = request.form.get('nickname')
        passw = request.form.get('password')
        user=User.query.filter(User.username==usern).first()
        if user:
            return '用户名已存在。'
        else:
            user1=User(username=usern,password=passw,nickname=nickn)
            db.session.add(user1)
            db.session.commit()
            return redirect(url_for('login'))#重定回向登录页面

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

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

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

注册：

{% extends 'base.html'%}
{% block title %}
注册
{% endblock %}
{% block head %}
<link rel="stylesheet" type="text/css"  href="{{url_for('static',filename='css/register.css') }}">
    <script src="{{url_for('static',filename='js/register.js') }}"></script>
{% endblock %}
{% block main %}
    <div class="box">
        <h2>注册</h2>
        <form action="{{url_for('register')}}" method="post">
         <div class="input_box">
             <input type="text" id="uname" placeholder="请设置用户名" name="username">
         </div>
        <div class="input_box">
             <input type="text" id="unumber" placeholder="请输入昵称" name="nickname">
         </div>
         <div class="input_box">
           <input type="password" id="upass" placeholder="请设置登录密码" name="password">
         </div>
        <div class="input_box">
             <input type="password" id="uupass" placeholder="请再次输入登录密码">
         </div>
         <div id="error_box"><br></div>
        <div class="lianjie">
             <a href="{{url_for('login')}}">已有账户，前往登录</a>
         </div>
         <div class="input_box">
             <button id="register" onclick="return check()">register </button>
         </div>
        </form>
    </div>
{% endblock %}

function check() {
        var oUname = document.getElementById("uname");
        var oPass = document.getElementById("upass");
        var onumber = document.getElementById("unumber");
         var ooPass = document.getElementById("uupass");
        var oError = document.getElementById("error_box");
        oError.innerHTML = "<br>";
        if (oUname.value.length < 6 || oUname.value.length > 20) {
            oError.innerHTML = "用户名为6-20位。";
            return false;
        }
        else if((oUname.value.charCodeAt(0)>=48)&&(oUname.value.charCodeAt(0)<=57)){
            oError.innerHTML="用户名首位不能为数字";
            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 = "用户名只能包括字母和数字";
                    return false;
                }
            }
        }

        if (oPass.value.length < 6 || ooPass.value.length > 20) {
            oError.innerHTML = "密码为6-20位。";
            return false;
    }
        if (oPass.value != uupass.value) {
            alert('两次输入密码不一致');
            return false;
        }
return true;
// window.alert("注册成功！");
    }