Question

I need to let a user create an Event which has a Category.When a user goes to the create_event page he is shown a dropdown list of Category instances.I need to make sure that only those Category s created by the user should be shown in the dropdown list

I tried to subclass Form for this sothat I can use it as below in view and template.

template for create_event:

<h3>select from existing categories</h3>
{{category_choices_form.as_p}}

view for create_event:

def create_event(request,..):
    user_categories = Category.objects.filter(creator=request.user)
    form_data = get_form_data(request)
    category_choices_form = CategoryChoicesForm(request.user,form_data)# is this correct?
    ...

def get_form_data(request):
    return request.POST if request.method == 'POST' else None

Then I created the Form subclass

class CategoryChoicesForm(forms.Form):
    def __init__(self, categorycreator,*args, **kwargs):
        super(CategoryChoicesForm, self).__init__(*args, **kwargs)
        self.creator=categorycreator
    categoryoption = forms.ModelChoiceField(queryset=Category.objects.filter(creator=self.creator),required=False,label='Category')

However, the line starting categoryoption = causes error saying name 'self' is not defined

Can somebody help me with this?

Answer 1

When you have a model that you want to expose as an html form, always prefer
to use a ModelForm instead of a simple form. Unless of course you’re doing
a lot of weird or complicated stuff and building a simple form is more straightforward.

So in your situtation

from django.forms import ModelForm

class CategoryForm(ModelForm):
    class Meta:
        model = Category
        # exclude = ('blah', 'foo') # You can exclude fields from your model, if you dont want all of them appearing on your form.

Your get_form_data function is unnecessary. This is how you use your form in a view

from django.template import RequestContext
from django.shortcuts import render_to_response

def create_event(request,..):
    if request.method == 'POST':
        form = CategoryForm(request.POST)
        if form.is_valid():
            # do stuff and redirect the user somewhere

    else:
        # We're in a GET request, we just present the form to the user
        form = CategoryForm()
    return render_to_response('some_template.html', {'form':form}, context_instance=RequestContext(request))

---

About the self is not defined error:

in your CategoryChoicesForm you have this line

    categoryoption = forms.ModelChoiceField(queryset=Category.objects.filter(creator=self.creator),required=False,label='Category')

This is at the class level, when self can be used only on an instance level. self is not “visible” there. It would be visible inside a method of CategoryChoicesForm though.