inlineformset_factory create new objects and edit objects after created

Question

In the django docs, there's an example of using inlineformset_factory to edit already created objects

https://docs.djangoproject.com/en/dev/topics/forms/modelforms/#using-an-inline-formset-in-a-view

I changed the example to be this way:

def manage_books(request):
    author = Author()
    BookInlineFormSet = inlineformset_factory(Author, Book, fields=('title',))
    if request.method == "POST":
        formset = BookInlineFormSet(request.POST, request.FILES, instance=author)
        if formset.is_valid():
            formset.save()
            return HttpResponseRedirect(author.get_absolute_url())
    else:
        formset = BookInlineFormSet(instance=author)
    return render_to_response("manage_books.html", {
        "formset": formset,
    })

With the above, it renders only the inline model without the parent model.

To create a new object, say Author, with multiple Books associated to, using inlineformset_factory, what's the approach?

An example using the above Author Book model from django docs will be helpful. The django docs only provided example of how to edit already created object using inlineformset_factory but not to create new one

Answer 1

I've done that using Django Class-Based Views.

Here's my approach:

models.py

from django.db import models

class Author(models.Model):
    name = models.CharField(max_length=100)


class Book(models.Model):
    author = models.ForeignKey(Author)
    title = models.CharField(max_length=100)

forms.py

from django.forms import ModelForm
from django.forms.models import inlineformset_factory

from crispy_forms.helper import FormHelper
from crispy_forms.layout import Layout, Fieldset

from .models import Author, Book

class AuthorForm(ModelForm):
    class Meta:
        model = Author
        fields = ('name', )

    @property
    def helper(self):
        helper = FormHelper()
        helper.form_tag = False # This is crucial.

        helper.layout = Layout(
            Fieldset('Create new author', 'name'),
        )

        return helper


class BookFormHelper(FormHelper):
    def __init__(self, *args, **kwargs):
        super(BookFormHelper, self).__init__(*args, **kwargs)
        self.form_tag = False
        self.layout = Layout(
            Fieldset("Add author's book", 'title'),
        )


BookFormset = inlineformset_factory(
    Author,
    Book,
    fields=('title', ),
    extra=2,
    can_delete=False,
)

views.py

from django.views.generic import CreateView
from django.http import HttpResponseRedirect

from .forms import AuthorForm, BookFormset, BookFormHelper
from .models import Book, Author

class AuthorCreateView(CreateView):
    form_class = AuthorForm
    template_name = 'library/manage_books.html'
    model = Author
    success_url = '/'

    def get(self, request, *args, **kwargs):
        self.object = None
        form_class = self.get_form_class()
        form = self.get_form(form_class)
        book_form = BookFormset()
        book_formhelper = BookFormHelper()

        return self.render_to_response(
            self.get_context_data(form=form, book_form=book_form)
        )

    def post(self, request, *args, **kwargs):
        self.object = None
        form_class = self.get_form_class()
        form = self.get_form(form_class)
        book_form = BookFormset(self.request.POST)

        if (form.is_valid() and book_form.is_valid()):
            return self.form_valid(form, book_form)

        return self.form_invalid(form, book_form)

    def form_valid(self, form, book_form):
        """
        Called if all forms are valid. Creates a Author instance along
        with associated books and then redirects to a success page.
        """
        self.object = form.save()
        book_form.instance = self.object
        book_form.save()

        return HttpResponseRedirect(self.get_success_url())

    def form_invalid(self, form, book_form):
        """
        Called if whether a form is invalid. Re-renders the context
        data with the data-filled forms and errors.
        """
        return self.render_to_response(
            self.get_context_data(form=form, book_form=book_form)
        )

    def get_context_data(self, **kwargs):
        """ Add formset and formhelper to the context_data. """
        ctx = super(AuthorCreateView, self).get_context_data(**kwargs)
        book_formhelper = BookFormHelper()

        if self.request.POST:
            ctx['form'] = AuthorForm(self.request.POST)
            ctx['book_form'] = BookFormset(self.request.POST)
            ctx['book_formhelper'] = book_formhelper
        else:
            ctx['form'] = AuthorForm()
            ctx['book_form'] = BookFormset()
            ctx['book_formhelper'] = book_formhelper

        return ctx

urls.py

from django.conf.urls import patterns, url
from django.views.generic import TemplateView

from library.views import AuthorCreateView

urlpatterns = patterns('',
    url(r'^author/manage$', AuthorCreateView.as_view(), name='handle-books'),
    url(r'^$', TemplateView.as_view(template_name='home.html'), name='home'),
)

manage_books.html

{% load crispy_forms_tags %}

<head>
  <!-- Latest compiled and minified CSS -->
  <link rel="stylesheet"
    href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.4/css/bootstrap.min.css">
</head>

<div class='container'>
  <form method='post'>
    {% crispy form %}
    {{ book_form.management_form }}
    {{ book_form.non_form_errors }}

    {% crispy book_form book_formhelper %}
    <input class='btn btn-primary' type='submit' value='Save'>
  </form>
<div>

Notice:

• This is a simple runable example that use the inlineformset_factory feature and Django generic Class-Based Views
• I'm assumming django-crispy-forms is installed, and it's properly configured.
• Code repository is hosted at: https://bitbucket.org/slackmart/library_example

I know it's more code that the showed solutions, but start to using Django Class-Based Views is great.