问python : ValueError:视图没有返回HttpResponse对象。它没有返回任何东西

EN

from django.contrib import admin
#from django.urls import path
from django.conf.urls import url
from khobor import views

urlpatterns = [
    url(r'^$', views.home, name='home'),
    url(r'^admin/', admin.site.urls),
    url(r'^find_feed/', views.find_feed, name="find_feed"),
    url(r'^show_articles/', views.show_articles, name="show_articles"),
    url(r'^clear_cookie/', views.clear_cookie, name="clear_cookie"),
    url(r'^show_recommendation', views.show_recommendation, name="show_recommendation"),
    ]

       $.ajax({

                    url:"/show_recommendation/",
                    method:"POST",
                    dataType: 'JSON',
                   data:{
                      id_found:id_found,
                      csrfmiddlewaretoken: '{{ csrf_token }}'

                    },
                    success:function (data) {

                        //data=$.parseJSON(data);

                        alert(data);
                        if(window.console){

                            console.log(" response data =  ");
                            console.log(data);
                        }



                         if($.isArray(data)){


                        for(i=0; i<data.length; i++){

                            var id_found=data[i][0];

                            if(window.console){

                                console.log(" id found = "+id_found+" id found result = "+jQuery.inArray(id_found, ids_all));

                            }
                            if(jQuery.inArray(id_found, ids_all) ==-1){





                                ids_all.push(id_found);
                                new_ids.push(id_found);

                            if(window.console){

                                console.log(" id pushed = "+id_found);

                            }



                            //$("#recommendations").append('<li>'+data[i][0]+' ... '+data[i][1]+'</li>');
                            $("#recommendations").append('<li class="article_indiv  inline_block">' +
                                '<span class="top_image inline_block"  data-id="'+data[i][0]+'" ><img src="'+data[i][4]+'" alt="image"/>'+
                                '</span>' +
                                '<a class="link" data-id="'+data[i][0]+'" target="_blank"  href="'+data[i][2]+'" >'+data[i][3]+'</a>' +
                                 '</li>');

                             $(".top_image").imagefill();

                           /* $(".top_image").each(function(){

                                $elem = $(this);
                                var data_id =$elem.attr('data-id');
                                if(jQuery.inArray(data_id, new_ids) !=-1){

                                    $elem.imagefill();

                                }

                            });*/

                            }
                         } // end of for loop

                        Cookies.set('ids_all', ids_all);
                         }


                }


            });

def show_recommendation(request):

    # recommendations=['item1','item2']
    # json_list=json.dumps(recommendations)

    if request.method=="POST" and request.is_ajax():
        #print("u see this response ? ");
        #return HttpResponse("this is the response ")
        id_found = request.POST['id_found'];
        news_found=news.objects.get(id=id_found)
        content_found=news_found.content


        all_news = news.objects.exclude(id=id_found).order_by('-id').all()
        myList=[]


        for news_indiv in all_news:
            content=news_indiv.content
            id=news_indiv.id
            headline=news_indiv.headline
            url=news_indiv.url
            image=news_indiv.image
            result_similarity=cosine_sim(content,content_found)
            myList.append([id, result_similarity,url,headline,image])


        # myList = [3, 2, 5, 6, 1, 0, -5, 6, -7]
        # myList = [[12, .45633], [13, .245633], [14, .3323], [15, .8756]]

        result = quickSort(myList)
        total_rows = len(result)
        resultList=[]
        resultList.append(result[total_rows-1])
        resultList.append(result[total_rows-2])
        resultList.append(result[total_rows-3])
        #print("resultList === ")
        #print(resultList)

        json_list = json.dumps(resultList)

        #if(json_list is None):
        #   json_list="0";


        print ("before HttpResponse ")
        return HttpResponse(json_list)
        #return HttpResponse("dfdfdfdf")
        #return json_list

Internal Server Error: /show_recommendation/

Traceback (most recent call last):

  File "/usr/lib64/python3.6/site-packages/django/core/handlers
/exception.py", line 35, in inner

    response = get_response(request)

  File "/usr/lib64/python3.6/site-packages/django/core/handlers/base.py", 

line 139, in _get_response

    "returned None instead." % (callback.__module__, view_name)

ValueError: The view khobor.views.show_recommendation didn't return an 

HttpResponse object. It returned None instead.

[03/Jun/2018 21:00:44] "POST /show_recommendation/ HTTP/1.1" 500 54424