完成登陆功能，用session记住用户名

登陆功能完成：

1. js:设置return
2. html:设置
   1. form
   2. input

   3. onclick="return fnLogin()"

3. py:
   1. @app.route设置methods
   2. GET
   3. POST
      1. 读取表单数据
      2. 查询数据库
         1. 用户名密码对：
            1. 记住用户名
            2. 跳转到首页
         2. 用户名密码不对：
            1. 提示相应错误。

session：

1. 从`flask`中导入`session`
2. 设置`SECRET_KEY`
3. 操做字典同样操做`session`：增长用户名`session['username']=`username

链接页面

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


app = Flask(__name__)
app.config.from_object(sqlconnect)#app链接数据库
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()

#增长
# user = User(username ='xxxxx1',password ='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():
    if request.method =='GET':
        return render_template("sign_in.html")
    else:
        name = request.form.get('name')
        passw = request.form.get('password')
        user = User.query.filter(User.username == name).first()
        #判断用户名是否存在
        if user:
            #判断密码是否正确
            if user.password == passw:
                session['user']=name#记住用户名
                return redirect(url_for('base'))
            else:
                return u'密码错误！'
        else:
            return u'不存在该用户名！'


@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陆界面


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


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

链接数据库

import os

SQLALCHEMY_DATABASE_URI='mysql+pymysql://root:@127.0.0.1:3306/data?charset=utf8'
SQLALCHEMY_TRACK_MODIFICATIONS =False

SECRET_KEY=os.urandom(24)

登陆.js页面 增长return false

function myLogin(){
            var uName = document.getElementById("name");
            var uPass = document.getElementById("pass");
            var uError = document.getElementById("error_box");


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