I have a specific formset (inlineformset), and I want to make some customization regarding the default design.

I loop thru it this way:

% for form in formset %
 <div class="ct-formset">
 % if form.errors %<div> form.errors </div>% endif %
 % for field in form % field % endfor %

 % endfor % 

For each form Django add two other fields the Foreign key field and the Delete Field.

Because I want to use the same code for multiple formsets, In the loop I don't request the field by name

I need to know in the:

 % for field in form % field % endfor %

How can I know which are my default form fields and which are the ones added by Django ?

While working with the form instance, you can't tell for sure what fields are added originally in the class or after instantiation.

Though, here you have some approaches on how to prevent those fields you don't want to be rendered in the resulting formset.

If you have access to the form's class ...

... at the moment you need to "filter" which fields where the original fields of such form you could:

>>> class MyForm(forms.Form):
>>> title = forms.CharField()

>>> class_dict = vars(MyForm)

>>> class_dict['declared_fields']

OrderedDict([('title', <django.forms.fields.CharField at 0x7f496ce067d0>)])

About *-DELETE and *-ORDER fields

When dealing with formsets, you must to have into account that not only Django can add extra fields to your forms, you also can do that.

First, we have to understand why these fields are there.

The case for the *-DELETE and *-ORDER fields are added just if you enable them using:

formset = formset_factory(..., can_delete=True, can_order=True)

Django uses BaseFormSet.add_fields in order to add that extra fields it needs to enable ordering or deletion, you could use it to add your own additional fields too.

What can you do?

You can just pass False there.

An interesting experiment ...

I perform an experiment in order to illustrate the effect overwritting this can have:

from django import forms

class MyForm(forms.Form):
 title = forms.CharField()

class MyBaseFormSet(forms.BaseFormSet):
 def add_fields(self, form, i):
 # Avoiding FormSets using this to add additional fields
 return form

# Create a form set with deletion and ordering enabled.
# pay attention to the argument: formset=MyBaseFormSet
MyFormSet = forms.formset_factory(MyForm, formset=MyBaseFormSet, can_delete=True, can_order=True)

fs = MyFormSet()
for form in fs:
 print(form.as_table())

The result, no DELETE or ORDER fields added to the resulting forms.

>>> <tr><th><label for="id_form-0-title">Title:</label></th><td><input type="text" name="form-0-title" id="id_form-0-title" /></td></tr>

What about ForeignKey

That's something you can solve in the forms. If you don't want ForeignKey to be displayed, you could use forms.HiddenInput widget for such fields in your forms.

Also if you're working with ModelForms you can select the fields to use for generating the form.

Conclusion

With this info, I hope you to be able to plan how to implement your requirement of having a generic template for those formsets.

Starting points:

1. Pass can_delete or/and start_order as False to formset_factory.


2. Set forms.HiddenInput widget for ForeignKey fields in your forms.


3. Find a way to get the form class and use vars in order to find out the
   original fields of the form.


4. If you're using ModelForms, use the fields or exclude meta configuration in order to state which fields are used to build the form.