Use formsets

Problem

You want a single page that submits several form rows at once.

Solution

Build the formset with Django’s formset_factory, register an action that takes the formset as its form parameter, and render every row in the template.

Walkthrough

Define the row form and the formset.

notes/forms.py

from django.forms import formset_factory
from next.forms import ModelForm
from notes.models import Note

class NoteRowForm(ModelForm):
    class Meta:
        model = Note
        fields = ("title", "body")
        abstract = True

NoteFormSet = formset_factory(NoteRowForm, extra=3, can_delete=True)

abstract = True matters here. Without it, subclassing ModelForm would register NoteRowForm as the standalone action note_row_form through __init_subclass__. That is a live endpoint that saves a single row through the default on_valid, even though only the formset action is intended. The flag suppresses that registration, and formset_factory still builds the formset from the abstract class as usual. See Preventing registration for the Meta.abstract semantics.

Register the action.

notes/pages/notes/bulk/page.py

from django.forms.formsets import BaseFormSet
from django.http import HttpRequest, HttpResponseRedirect

from next import action
from next.forms import redirect_to_origin
from notes.forms import NoteFormSet

def build_bulk_formset() -> tuple[type[BaseFormSet], dict]:
    return NoteFormSet, {"prefix": "notes"}

@action("bulk_create", form_class=build_bulk_formset)
def bulk_create(request: HttpRequest, form: NoteFormSet) -> HttpResponseRedirect:
    for row in form:
        if row.cleaned_data and not row.cleaned_data.get("DELETE"):
            row.save()
    return redirect_to_origin(request)

Passing a formset class directly to @action’s form_class is accepted at decoration time but fails at request time. The dispatcher calls get_initial on a directly passed class, and Django formset classes have none. Register a factory callable that returns a (FormSetClass, init_kwargs) tuple instead. The init_kwargs reach the formset constructor, and a non-empty dict makes the dispatcher skip the get_initial step. A formset has no get_initial, so the init_kwargs must be non-empty even if they only set the prefix.

redirect_to_origin reads the posted origin path, so a successful submission lands back on the bulk page.

Render the formset.

notes/pages/notes/bulk/template.djx

{% form "bulk_create" %}
  {{ form.management_form }}
  {% for row in form %}
    <fieldset>
      <legend>Row {{ forloop.counter }}</legend>
      {{ row.title }}
      {{ row.body }}
      {{ row.DELETE }}
    </fieldset>
  {% endfor %}
  <button type="submit">Save all</button>
{% endform %}

Always render {{ form.management_form }} before the row loop. can_delete=True adds the DELETE checkbox to every row, and the handler skips the rows the user marked, so the template renders it alongside the fields.

Clean up empty rows

A formset with extra=3 ships three blank rows. Field-level initials, declared on the row form or inherited from model field defaults, pre-populate those blank rows. An untouched pre-filled row no longer looks empty to Django, so it validates as a partial submission and triggers errors. Use cleanup_extra_initial to clear initial values from blank extra rows before the formset is rendered.

notes/pages/notes/bulk/page.py

from types import SimpleNamespace

from next import context
from next.forms import cleanup_extra_initial
from notes.forms import NoteFormSet

@context("bulk_create")
def bulk_create_form() -> SimpleNamespace:
    formset = NoteFormSet(prefix="notes")
    cleanup_extra_initial(formset)
    return SimpleNamespace(form=formset)

The {% form %} tag first looks up a context variable named after the action and reads its .form attribute. When the variable is absent the tag builds the namespace itself from the registered factory, so a plain render needs no @context at all. Publish the namespace only to customise construction, here to clean the field-level initials off the blank extra rows. The context key passed to @context must match the action name, and the returned object must expose .form, hence the SimpleNamespace(form=...) wrapper.

Verification

Submit the formset with two filled rows and one blank row. The handler saves the two filled rows and skips the blank one. A row that fails validation re-renders with errors on that row only.

See also

See also

Formsets for the topic guide. Validation and re-render for the failure flow.