def post_detail(request, pk):
    template_name = 'books/post-detail.html'
    book = get_object_or_404(Book, pk=pk)
    comments = book.comments.filter(active=True)
    new_comment = None
    # Comment posted
    if request.method == 'POST':
        comment_form = CommentForm(data=request.POST)
        if comment_form.is_valid():

            # Create Comment object but don't save to database yet
            new_comment = comment_form.save(commit=False)
            # Assign the current post to the comment
            new_comment.comment = book
            new_comment.username = request.user
            # Save the comment to the database
            new_comment.save()
    else:
        comment_form = CommentForm()

    context = {'book': book,
                'comments': comments,
                'new_comment': new_comment,
                'comment_form': comment_form}

    return render(request, template_name, context)