Django: multiple models in one template using forms

Question

I'm building a support ticket tracking app and have a few models I'd like to create from one page. Tickets belong to a Customer via a ForeignKey. Notes belong to Tickets via a ForeignKey as well. I'd like to have the option of selecting a Customer (that's a whole separate project) OR creating a new Customer, then creating a Ticket and finally creating a Note assigned to the new ticket.

Since I'm fairly new at Django, I tend to work iteratively, trying out new features each time. I've played with ModelForms but I want to hide some of the fields and do some complex validation. It seems like the level of control I'm looking for either requires formsets or doing everything by hand, complete with a tedious, hand-coded template page, which I'm trying to avoid.

Is there some lovely feature I'm missing? does someone have a good reference / example for using formsets? I spent a whole weekend on the API docs for them and I'm still clueless. Is it a design issue if I break down and hand-code everything?

Thanks in advance!

Answer 1

"I want to hide some of the fields and do some complex validation."

I start with the built-in admin interface.

1. Build the ModelForm to show the desired fields.

2. Extend the Form with the validation rules within the form. Usually this is a clean method.

   Be sure this part works reasonably well.

Once this is done, you can move away from the built-in admin interface.

Then you can fool around with multiple, partially related forms on a single web page. This is a bunch of template stuff to present all the forms on a single page.

Then you have to write the view function to read and validated the various form things and do the various object saves().

"Is it a design issue if I break down and hand-code everything?" No, it's just a lot of time for not much benefit.

Answer 2

This really isn't too hard to implement with ModelForms. So lets say you have Forms A, B, and C. You print out each of the forms and the page and now you need to handle the POST.

if request.POST():
    a_valid = formA.is_valid()
    b_valid = formB.is_valid()
    c_valid = formC.is_valid()
    # we do this since 'and' short circuits and we want to check to whole page for form errors
    if a_valid and b_valid and c_valid:
        a = formA.save()
        b = formB.save(commit=False)
        c = formC.save(commit=False)
        b.foreignkeytoA = a
        b.save()
        c.foreignkeytoB = b
        c.save()

Here are the docs for custom validation.

Answer 3

I very recently had the some problem and just figured out how to do this. Assuming you have three classes, Primary, B, C and that B,C have a foreign key to primary

    class PrimaryForm(ModelForm):
        class Meta:
            model = Primary

    class BForm(ModelForm):
        class Meta:
            model = B
            exclude = ('primary',)

    class CForm(ModelForm):
         class Meta:
            model = C
            exclude = ('primary',)

    def generateView(request):
        if request.method == 'POST': # If the form has been submitted...
            primary_form = PrimaryForm(request.POST, prefix = "primary")
            b_form = BForm(request.POST, prefix = "b")
            c_form = CForm(request.POST, prefix = "c")
            if primary_form.is_valid() and b_form.is_valid() and c_form.is_valid(): # All validation rules pass
                    print "all validation passed"
                    primary = primary_form.save()
                    b_form.cleaned_data["primary"] = primary
                    b = b_form.save()
                    c_form.cleaned_data["primary"] = primary
                    c = c_form.save()
                    return HttpResponseRedirect("/viewer/%s/" % (primary.name))
            else:
                    print "failed"

        else:
            primary_form = PrimaryForm(prefix = "primary")
            b_form = BForm(prefix = "b")
            c_form = Form(prefix = "c")
     return render_to_response('multi_model.html', {
     'primary_form': primary_form,
     'b_form': b_form,
     'c_form': c_form,
      })

This method should allow you to do whatever validation you require, as well as generating all three objects on the same page. I have also used javascript and hidden fields to allow the generation of multiple B,C objects on the same page.

Answer 4

I just was in about the same situation a day ago, and here are my 2 cents:

1) I found arguably the shortest and most concise demonstration of multiple model entry in single form here: http://collingrady.wordpress.com/2008/02/18/editing-multiple-objects-in-django-with-newforms/ .

In a nutshell: Make a form for each model, submit them both to template in a single <form>, using prefix keyarg and have the view handle validation. If there is dependency, just make sure you save the "parent" model before dependant, and use parent's ID for foreign key before commiting save of "child" model. The link has the demo.

2) Maybe formsets can be beaten into doing this, but as far as I delved in, formsets are primarily for entering multiples of the same model, which may be optionally tied to another model/models by foreign keys. However, there seem to be no default option for entering more than one model's data and that's not what formset seems to be meant for.