Django - ModelForms rendered indexed by foreignKey and that value POSTed - django

Question

A simple and logical extension of the tutorial polls app would be showing several questions per page with a single 'submit' button. I've got a hybrid design that uses ModelForms for multi-field questions but individually rendered fields for single-field questions. So the standard question_set page is rendered by:
{% load custom_tags %}
{% block question_set %}
<form action="{% url 'polls:answer' user.username %}" method="POST">
{% csrf_token %}
{% for question in page_question_list %}
<hr/>
{% if question.answer_type == "CH" %}
{% include "polls/Choice_Answer_form.html" %} {%endif%}
{% if question.answer_type == "SA" %}
{% include "polls/Short_Answer_form.html" %} {%endif%}
{% if question.answer_type == "LA" %}
{% include "polls/Long_Answer_form.html" %} {%endif%}
{% if question.answer_type == "E3" %}
{% include "polls/EJ_Answer_form.html" with form=forms|get_item:question%}
{%endif%}
{% if question.answer_type == "E4" %}
{% include "polls/EJ_Answer_form.html" with form=forms|get_item:question%}
{%endif%}
{% if question.answer_type == "BS" %}
{% include "polls/brainstorm_form.html" %}
{% endif %}
{% endfor %}
<br/>
<hr/>
<input type="submit" value="Submit" />
</form>
{% endblock %}
I have a sense that I have missed something fundamental about how forms are supposed to work. When you create a ModelForm object and send it out to be rendered, it knows what instance (in my case, question number and user_id) it corresponds to in the model. When it comes back from the browser, that information is gone if you have disabled, read-only'd or hidden those (id, pk etc) fields. You could put that information in the url, but it will only be feasible if you are dealing with a single row of data on each page. In the docs are [examples][1] cheerfully showing how to ModelForm(request=request, instance=instance) but I don't know how to design it so that the request and the instance stay in sync.
Some strategies I've looked into:
bundle needed forms in formsets and use the 'prefix' to differentiate them. Not sure that the question number association can be retained for rendering (suspect it can) or recovered if it is still dropped from the POST data (suspect it can't).
modifying the rendered field-names to include the Key information (question number, user) to prevent them overlapping in html namespace and only the last values being submitted e.g. generate a new field for the form with the data in it to be rendered and presumably passed back or define a function to set a html_field_name in the constructor.
use the form 'auto_id' (see docs) string to give every field a unique name that encodes question number - suspect this ought to be redundant and better handled by the pros in a formset, but see my first idea.
I probably want to try the easiest and best first; any advice gratefully received.
(I had a bunch more links but am not allowed to post them with so little status)

Answer 1

I found that loading and retrieving the question number from the 'prefix' (but not auto_id) field as a string "qNN#" for each form can work (because the prefix is applied to the element name and auto_id applies to the id, and its the name that the POST data uses). I've put all this logic in 'views.py'
The view that catches the submitted form has to look at the keys in request.POST and when it finds a key beginning with q, it works out what question the fields come from and passes the request off with the question to create the form from the request + prefix.
This means that request.POST is sent to my form_instantiator helper function each time there is form_data to be found, rather than submitting them as a group to be iterated over.
I feel guilty of cruelty to Django, somehow.