django 的auth.authenticate返回为None

#coding = utf-8
from django.shortcuts import render
from django.http import JsonResponse
import time
from django.views.decorators.csrf import csrf_exempt
from sign1.models import smile_task_user
from django.core.exceptions import ValidationError
from django.contrib import auth
from django.contrib.auth.models import User



#注册接口POST /register username/password
@csrf_exempt
def register(request):

    username = request.POST.get(‘username‘,‘‘)
    password = request.POST.get(‘password‘,‘‘)
    regist_time = time.strftime("%Y-%m-%d %H:%M:%S")

    if username=="" or password =="" :
        return JsonResponse({‘message‘:‘username or passowrd is null !!!‘})
    
    result = User.objects.filter(username = username)
    if result:
        return JsonResponse({‘message‘:‘username is already exists !!!‘})

    try:
        User.objects.create_user(username=username,password=password)
        
    except ValidationError as e:
        error = "####create data worng#############"
        return JsonResponse({‘ststus‘:10024,‘message‘:error})
    return JsonResponse({‘username‘:username,‘regist_time‘:regist_time,‘message‘:‘regist ok!‘})

#登录接口POST /login username/password
@csrf_exempt
def login(request):
    if request.method =="POST":
        username=request.POST.get("username","")
        password=request.POST.get("password","")

        user=auth.authenticate(username=username,password=password)
        print(user)
        #user = smile_task_user.objects.filter(username = username,password = password)
        if user is not None:
                auth.login(request,user)
                request.session[‘user‘] = username # 将 session 信息记录到浏览器
                return JsonResponse({‘message‘:"login sucess"})
        else:
            return JsonResponse({‘message‘:"username or password is error!!"})