二十九、登录相关

def login(request):
    if request.method == 'GET':
        form = account.LoginForm()
        return render(request, 'login.html',{'form':form })
    else:
        form = account.LoginForm(request.POST)
        result = {'status': False, 'message': None, 'errors': None}
        if form.is_valid():
            name = form.cleaned_data['username']
            pwd = form.cleaned_data['password']
            userInfo = models.UserInfo.objects.filter(name=name,password=pwd).first()
            if userInfo:
                request.session['UserInfo'] = name
                return redirect('/')
            else:
                result['errors'] = '用户名或密码错误' # 这里是不兼容的地方，这个错误html不知道怎么显示给用户
            return render(request, 'login.html', {'form': form})
        else:
            return render(request, 'register.html', {'form': form})

def logout(request):
    request.session.clear()
    return redirect('/')

def index(request):
    // sessionid 未登录就已经有，因为进行http请求就是一次会话，未登录，session也有其它值在记录着
    username = request.session.get('UserInfo')  // 直接拿。不需要从cookies中拿sessionid，再拿session，底层已经做好
    return render(request, 'index.html', {'username':username})