With Django, how can I add my model's ForeignKey to CreateView?

Question

I'm making an app that allows people to set up instructional events that may span multiple days. Here's some of my code:

Models:

class Event(models.Model):
    event_name = models.CharField('Event Name', max_length=200)
    short_description = models.TextField('Short Description', max_length=140)

class EventDay(models.Model):
    event = models.ForeignKey(Event)
    day_name = models.CharField(max_length=30)
    start_time = models.DateTimeField('Starting Date and Time')
    end_time = models.DateTimeField('Estimate Ending Time')

Views

from .models import Event, EventDay

class EventCreate(LoginRequiredMixin, CreateView):
    model = Event
    fields = ['event_name', 'short_description']

In the admin when I add an event it works perfectly, allowing me to add as many days to the event as I want. But the event add page outside of the admin only displays the fields from Event, not EventDay.

I know my Views code looks a little empty as far as anything relating to the EventDay goes. But, before posting here I tried as many different things as I could think of to try and get fields that work like the admin page. I just left out the mess I tried here. I also couldn't find anything in the docs about where I'm going wrong.

I didn't include my template/url code since I don't think that's the problem. Again I can add events, just not the EventDay part of it. But I'm new to this all so if you need me to post more code I will.

Answer 1

You're looking for inline formset.

CreateView can be used with this but I think you should use a TemplateView (a base class for CreateView) instead, which is simpler to extend/modify.

# forms.py
from django import forms
from .models import Event

class EventForm(forms.ModelForm):
    class Meta:
        model = Event


# views.py
from django.http import HttpResponseRedirect
from django.views.generic import TemplateView
from django.forms.models import inlineformset_factory
from .models import EventDay, Event
from .forms import EventForm

class EventCreate(TemplateView):
    template_name = 'event_create.html'

    def get(self, request, *args, **kwargs):
        "GET forms ready!"
        # get form for Event
        event_form = EventForm()
        # here's the 'magic' inlineformset, better read the
        # django documentation about this
        EventDayFormSet = inlineformset_factory(Event, EventDay)
        formset = EventDayFormSet()
        # add to context and return response
        context = {'form': event_form, 'formset': formset}
        return self.render_to_response(context)

    def post(self, request, *args, **kwargs):
        "Handle form submission on POST request"
        # get form for Event with POST data
        event_form = EventForm(data=request.POST)
        # get formset for EventDay with POST data
        EventDayFormSet = inlineformset_factory(Event, EventDay)
        formset = EventDayFormSet(data=request.POST)
        if event_form.is_valid() and formset.is_valid():
            # valid forms, OK to save
            event = event_form.save()
            # EventDay needs a ForeignKey for Event since the field is
            # not nullable. Save the forms without committing to database...
            eventdays = formset.save(commit=False)
            for eventday in eventdays:
                # ... and add the ForeignKey field
                eventday.event = event
                eventday.save()
            # TODO use reverse('name_of_the_view_to_redirect_to') instead of '/'
            return HttpResponseRedirect('/')
        # Some error occurred with the forms, display errors and forms
        # so the user can fix it
        context = {'form': event_form, 'formset': formset}
        return self.render_to_response(context)

To know a bit more about class base views structure and which method to override and the like, checkout Classy Class Based Views.