The QuerySet value for an exact lookup must be limited to one result using slicing-Django

Question

I'm building a news website. While I tried to get the list of relative news which have the same tags. The error said:

The QuerySet value for an exact lookup must be limited to one result using slicing.

I have two models News and Tag. Tag is a many-to-many foreign key of News.

News model:

class News(models.Model):
  
    tag = models.ManyToManyField(Tag, blank=True, verbose_name='tag')
    

Tag model:

class Tag(models.Model):

    name = models.CharField(max_length=40)

View:

def newsDetailView(request, news_pk):
    news = get_object_or_404(News, id=news_pk)
    tags = news.tag.annotate(news_count=Count('news'))
    relative_news = News.objects.filter(tag=tags)

    return render(request, "news_detail.html", {
        'news': news,
        'tags': tags,
        'relative_news': relative_news
    })

Answer 1

The problem you are facing is that you first take a filter queryset (a collection of objects from your database) for example: Book.objects.filter(subject='fiction') ) and then you are trying to use that filter as a parameter (like subject = 'fiction' in the previous one ) to obtain another filter queryset.

Instead you have to use an object using 'get' instead of 'filter' that is the previous example would become

book = Book.objects.get(subject='fiction')

and then use that object as parameter for next filter.

example: Book_shelf = BookShelf.objects.filter(book = book)

Answer 2

The following will work:

def newsDetailView(request, news_pk):
    news = get_object_or_404(News, id=news_pk)
    relative_news = News.objects.filter(tag__id__in=news.tag.all())

Answer 3

Generally this error occurs when we use model queryset at the place of django models object. In the given question you have done the same. "Objects.filter" returns the model query set there can be single or multiple django model objects, but "objects.get" returns single django model object. Or we can use .last() and .first() with "objects.filter".