登录功能和数据库校验：

from django.shortcuts import render,HttpResponse,redirect
import pymysql

# Create your views here.

def index(request):
    print(request.path_info)
    return HttpResponse('<h1>index</h1>')
    # return render(request, 'index.html')

def modal(request):
    return render(request, 'modal.html')

def login(request):
    # 判断如果是get请求返回登录页面：
    if request.method == "GET":
        return render(request,"login.html")
    # 否则处理post请求、获取提交数据：
    else:
        print(request.POST)
        #获取用户名：
        username = request.POST.get("user")
        password = request.POST.get("password")
        #用户名和密码校验：
        conn = pymysql.connect ( user="root", password="123", db="alex", charset="utf8" )
        cursor = conn.cursor ()
        ret = cursor.execute ( "select * from user where username = %s and password = %s",(username,password))
        if ret:
            #登录成功：
            return redirect("/index/")
        else:
            return render(request,"login.html",{"error":"用户名或密码错误"})