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

        存到数据库中

        redirect重定向到登录页

代码如下：

from flask import Flask
from flask import render_template,request,redirect,url_for
import config

from flask_sqlalchemy import SQLAlchemy
app = Flask(__name__)
app.config.from_object(config)
db = SQLAlchemy(app)

class User(db.Model):
    __tablename__ = 'user'
    # 建立一个表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)
    say = db.Column(db.String(50))

# db.create_all()


# 添加数据
# user=User(username='yujiujiu2',password='11111')
# db.session.add(user)
# db.session.commit()
#

# 查找数据
# user=User.query.filter(User.username=='yujiujiu').first()
# print(user.username,user.password)


# 修改数据
# user=User.query.filter(User.username=='yujiujiu').first()
# user.password='666667'
# print(user.username,user.password)
# db.session.commit()


# 删除数据
# user=User.query.filter(User.username=='yujiujiu2').first()
# db.session.delete(user)
# db.session.commit()
#


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


@app.route('/zhuce/',methods=['GET','POST'])
def zhuce():
    if request.method=='GET':
        return render_template('zhuce.html')
    else:
        username=request.form.get('username')
        password=request.form.get('password')
        say=request.form.get('say')
        user=User.query.filter(User.username==username).first()
        #判断用户名是否存在
        if user:
            return u' username existed'
        else:
            user=User(username=username,password=password,say=say)
            db.session.add(user)
            db.session.commit()
            return redirect(url_for('login'))
#重新定向到登录页

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

zhuce.html

  {% extends 'basic.html'%}
  {% block aa %}
    <link rel="stylesheet" type="text/css" href="{{url_for('static',filename="css/zhuce.css")  }}">
        <script language="javascript" type="text/javascript" src="{{url_for('static',filename="js/zhuce.js")  }}"></script>
<div id=mao ><p></p>
    <div id="header"><h2 align="center"></h2></div>
    <div id="content" >

        <form action="{{ url_for('zhuce')}}" method="post"><br/>


            <div class="form-group">
                <label for="uname" class="col-sm-2 control-label">Username:</label>
                <div class="col-sm-10">
                    <input type="text" class="form-control" id="uname" name="username"
                           placeholder="make your username"><br>
                </div>


            </div>
            <div class="form-group">
                <label for="upass" class="col-sm-2 control-label">Password:</label>
                <div class="col-sm-10">
                    <input type="text" class="form-control" id="upass" name="password"
                           placeholder="make your password"><br>
                </div>
            </div>


            <div class="form-group">
                <label for="upass2" class="col-sm-2 control-label">AgainPass:</label>
                <div class="col-sm-10">
                    <input type="text" class="form-control" id="upass2"
                           placeholder="again your password"><br>
                </div>
            </div>


<div class="form-group1"><label for="question" >SomethingSay</label>
<textarea class="col-sm-10" rows="3" id="question" name="say"></textarea><br><br><br><br>
</div>

            <div >
            <br>  &nbsp &nbsp <input type="radio" name="role" value="stu">student
            <input id="tea" type="radio" name="role" value="tea">teacher<br/>
            </div>
            <div id="error_box"  ></div>
            <div align="center">
               <input id="input_box" type="button" class="btn btn-default btn-lg active" value="注册" onclick="miao()">
             </div>
          </form>
</div>
</div>



  {% endblock %}

zhuce.js

 function miao(){
        var oUname=document.getElementById("uname");
        var oUpass=document.getElementById("upass");
        var oUpass2=document.getElementById("upass2");
        var oError=document.getElementById("error_box");
        var isError=true;
        oError.innerHTML="<br>"
    if (oUname.value.length<6 || oUname.value.length>12){
     oError.innerHTML="用户名6-12位";
     isError=false;
     return isError;
    } else if((oUname.value.charCodeAt(0)>=48)&&(oUname.value.charCodeAt(0)<=57)){
       oError.innerHTML="first letter";
       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 = "only letter or number";
                isError=false;
                return isError;
            }

        }

if (oUpass.value.length<6 || oUpass.value.length>12){
   oError.innerHTML="密码6-12位";
   return false;
}
    else if (oUpass.value!==oUpass2.value){
        oError.innerHTML="两次密码不一致";
        return false;
    }
    return true;
    // window.alert("注册成功！")

    }
 function mySwitch() {
    var oBody = document.getElementById("myBody");

    var oOnOff = document.getElementById("myOnOff");
    var ogui = document.getElementById("gui");
    if (oOnOff.src.match('bulbon')) {

        oOnOff.src = "http://www.runoob.com/images/pic_bulboff.gif";
        oBody.style.backgroundColor = "black";
        oBody.background="../static/img/h.jpg"
        oBody.style.color = "white";
        ogui.src = "https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1509563443074&di=b1bbb3f5714a580e2211e281124636c2&imgtype=0&src=http%3A%2F%2Fpic15.nipic.com%2F20110709%2F7854247_221301558161_2.jpg";
    } else {
        oOnOff.src = "http://www.runoob.com/images/pic_bulbon.gif";
        oBody.style.backgroundColor = "white";
        oBody.style.color = "black";
        ogui.src = "";
        oBody.background="../static/img/timg1.jpg"
    }
}

运行结果：