Django Alternative to PK in Form Action Parameter

Question

I have two models in a parent-child relationship: Idea and Comment. I am using DRF and nested DataTables to serve these models to the browser. To create a comment, the corresponding idea ID must be known. The button to create a new comment looks like this with parentObjData being the Idea id:

<button type="button" class="btn btn-primary js-create-idea-comment" data-url="/platform/ideas/comments/' + parentObjData + '/create/"><span class="fa fa-plus"></span> New Comment</button>

When clicked, this happens:

var loadForm = function () {
  var btn = $(this)
  $.ajax({
    url: btn.attr("data-url"),
    type: 'get',
    dataType: 'json',
    beforeSend: function () {
      $("#modal-activity").modal()
    },
    success: function (data) {
      $("#modal-activity .modal-content").html(data.html_form)
    }
  })
}

This works, and a request to the proper URL is sent when each button is clicked. What's supposed to happen with a successful request is demonstrated by these views:

def save_comment_form_create(request, form, template_name, parent_id):
    data = dict()
    if request.method == 'POST':
        if form.is_valid():
            instance = form.save(commit=False)
            instance.created_by_id = request.user.id
            instance.idea_id = parent_id
            form.save()
            data['form_is_valid'] = True
            comments = IdeaComment.objects.all()
            data['html_idea_comment_list'] = render_to_string('ic/includes/partial_idea_comment_list.html', {
                'comments': comments
            })
        else:
            data['form_is_valid'] = False
    context = {'form': form}
    data['html_form'] = render_to_string(template_name, context, request=request)
    return JsonResponse(data)


def idea_comment_create(request, parent_id):
    idea_id = parent_id
    if request.method == 'POST':
        form = IdeaCommentForm(request.POST)
    else:
        form = IdeaCommentForm()
    return save_comment_form_create(request, form, 'ic/includes/partial_idea_comment_create.html', idea_id)

partial_idea_comment_create.html resolves to this form:

<form method="post" action="{% url 'idea_comment_create' parent_id %}" class="js-idea-comment-create-form">
  {% csrf_token %}
  <div class="modal-header">
    <h4 class="modal-title">New Comment</h4>
    <button type="button" class="close" data-dismiss="modal" aria-label="Close">
      <span aria-hidden="true">&times;</span>
    </button>
  </div>
  <div class="modal-body">
    {% include 'ic/includes/partial_idea_comment_form.html' %}
  </div>
  <div class="modal-footer">
    <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
    <button type="submit" class="btn btn-primary">Create</button>
  </div>
</form>

And here is the URL:

url(r'^platform/ideas/comments/(?P<parent_id>\d+)/create/$', views.idea_comment_create, name='idea_comment_create'),

parent_id is the issue. If I hard code a number into partial_idea_comment_create.html, everything works great (except comments go to the wrong idea). The way it is now, I get this error:

NoReverseMatch at /platform/ideas/comments/1/create/
Reverse for 'idea_comment_create' with arguments '('',)' not found. 1 pattern(s) tried: ['platform/ideas/comments/(?P<parent_id>\\d+)/create/$']

For a normal pk that doesn't rely on a parent instance, I would do something like this:

<form method="post" action="{% url 'idea_update' form.instance.pk %}">

How should I dynamically load the parent_id into that URL?

I think this question gets partially there: How do I pass a parent id as an fk to child object's ModelForm using generic class-based views in Django? but I haven't been able to get it to work for me.

I don't see where you're passing the parent_id to the `partial_idea_comment_create.html` template context. Since it can't find `parent_id` it uses empty string — Ken4scholars, Apr 18 '19 at 23:44
that makes sense. how would I pass it? I thought I was with the Ajax request (i.e. `parentObjData` is the `parent_id`)...but I am admittedly all turned around. — OverflowingTheGlass, Apr 18 '19 at 23:46
Here - `data['html_form'] = render_to_string(template_name, context, request=request)` You need to include parent_id in the context data. `context = {'form': form, 'parent_id`: parent_id}` — Ken4scholars, Apr 18 '19 at 23:51
perfect - happy to accept this as an answer if you feel like making one. — OverflowingTheGlass, Apr 19 '19 at 00:50

score 1 · Accepted Answer · answered Apr 19 '19 at 01:31

The issue is that you're not passing the parent_id in the template context. This is what you should do in the save_comment_form_create method:

...
context = {'form': form, 'parent_id': parent_id}
data['html_form'] = render_to_string(template_name, context, request=request)
return JsonResponse(data)

Django Alternative to PK in Form Action Parameter

1 Answers1