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

主页面连接数据库

from flask import Flask,request,render_template,redirect,url_for
from flask_sqlalchemy import SQLAlchemy
import sqlconnect
from functools import wraps
from  datetime import datetime


app = Flask(__name__)
app.config.from_object(sqlconnect)#app连接数据库
db = SQLAlchemy(app)

class User(db.Model):
    __tablename__ ='user1'
    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)
    #againpass = db.Column(db.String(20), nullable=False)


#db.create_all()

#增加
# user = User(username ='xxxxx1',password ='123456',againpass='123456')
# db.session.add(user)
# db.session.commit()
#查找
# user = User.query.filter(User.username =='xxxxx1').first()
# user.password ='123456'
# user.againpass='123456'
# print(user.id,user.username,user.password)
#删除
# user = User.query.filter(User.username =='xxxxx1').first()
# db.session.delete(user)
# db.session.commit()

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

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

@app.route("/regiter",methods=['GET','POST'])
def sign_up():
    if request.method == 'GET':
        return render_template("sign_up.html")
    else:
        name = request.form.get('newname')
        passw = request.form.get('newpass')
        samename = User.query.filter(User.username == name).first()
        if samename:
            return u'username existed!'

        else:
            # 将用户名和密码存入数据库
            users =User(username = name ,password = passw)
            db.session.add(users)
            db.session.commit()
            return render_template("sign_in.html")#注册成功后跳转到登录界面


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


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

注册界面
function mySubmit(){
            var oNewname = document.getElementById("newname");
            var oNewpass = document.getElementById("newpass");
            var oAgainname = document.getElementById("againpass");
            var oError = document.getElementById("error_box");

            oError.innerHTML="<br>"
            //用户名
            if(oNewname.value.length<6 && oNewname.value.length>12) {
                oError.innerHTML = "User name must be between 6 and 12 digits!!!";
                return false;
            }
           else if ((oNewname.value.charCodeAt(0)>=48)&&(oNewname.value.charCodeAt(0)<=57)){
                oError.innerHTML = "The first letter can not be a number!!!";
                return false;
            }
            else for(var i=0;i<oNewname.value.length;i++){
                if((oNewname.value.charCodeAt(i)<48 || oNewname.value.charCodeAt(i)>57)&&(oNewname.value.charCodeAt(i)<97 || oNewname.value.charCodeAt(i)>122)){
                    oError.innerHTML = "Only number and letter!!! ";
                    return false;
                }
                }
            //密码
            if(oNewpass.value.length>12|| oNewpass.value.length<6){
                oError.innerHTML="The password must be between 6 and 12 digits!";
                return false;
            }
            else if(oNewpass.value != oAgainname.value) {
                oError.innerHTML="The password entered twice is not the same!!!";
                return false;
            }
            window.alert("Successful registration！")
            return true;
        }