#Post view
def post_detail(request, year, month, day, post):
    post = get_object_or_404(Post, slug = post,
                             status = 'published',
                             publish__year = year,
                             publish__month = month,
                             publish__day = day)
    #List of active comments for this post
    comments = post.comments.filter(active=True)
    sent = False
    if request.method == 'POST':
        #a comment was posted
        comment_form = CommentForm(data=request.POST)

        if comment_form.is_valid():
            #Create comment object but don't save to database yet(commit - false)
            new_comment = comment_form.save(commit=False)
            #Assign the current post(obj) to the comment
            new_comment.post = post
            #save it to the database
            new_comment.save()
            sent = True
    else:
        comment_form = CommentForm()
    return render(request,
                  'detail.html',
                  {'post': post,
                   'comments': comments,
                   'comment_form': comment_form,
                   'sent': sent})


#Template
...
{% if sent %}
        <h2>Your comment has been added.</h2>
...