Save Django Form wizard data to three models with related fields - django

Question

I am working on a project that requires use of form wizard to populate three related models. The first model - Listing - has general data which has a OneToOneField relationship with the second model (Property). The Listing model also has a many to many relationships with the third model (ListingImages). In general, I am using 4 forms in the wizard. Here is the models definition
models.py
class Listing(models.Model):
listing_type_choices = [('P', 'Property'), ('V', 'Vehicle'), ('B', 'Business/Service'), ('E', 'Events')]
listing_title = models.CharField(max_length=255)
listing_type = models.CharField(choices=listing_type_choices, max_length=1, default='P')
status = models.BooleanField(default=False)
featured = models.BooleanField(default=False)
city = models.CharField(max_length=255, blank=True)
location = PlainLocationField(based_fields=['city'], zoom=7, blank=True)
created_at = models.DateTimeField(auto_now_add=True)
updated_at = models.DateTimeField(auto_now=True)
expires_on = models.DateTimeField(auto_now=True)
created_by = models.ForeignKey(User,
on_delete=models.CASCADE, editable=False, null=True, blank=True
)
listing_owner = models.ForeignKey(User,
on_delete=models.CASCADE, related_name='list_owner'
)
def __str__(self):
return self.listing_title
def get_image_filename(instance, filename):
title = instance.listing.listing_title
slug = slugify(title)
return "listings_pics/%s-%s" % (slug, filename)
class ListingImages(models.Model):
listing = models.ForeignKey(Listing, on_delete=models.CASCADE)
image_url = models.ImageField(upload_to=get_image_filename,
verbose_name='Listing Images')
main_image = models.BooleanField(default=False)
class Meta:
verbose_name_plural = "Listing Images"
def __str__(self):
return f'{self.listing.listing_title} Image'
class Property(models.Model):
sale_hire_choices = [('S', 'Sale'), ('R', 'Rent')]
fully_furnished_choices = [('Y', 'Yes'), ('N', 'No')]
listing = models.OneToOneField(Listing, on_delete=models.CASCADE)
sub_category = models.ForeignKey(PropertySubCategory, on_delete=models.CASCADE)
for_sale_rent = models.CharField(choices=sale_hire_choices, max_length=1, default=None)
bedrooms = models.PositiveIntegerField(default=0)
bathrooms = models.PositiveIntegerField(default=0)
rooms = models.PositiveIntegerField(default=0)
land_size = models.DecimalField(max_digits=10, decimal_places=2)
available_from = models.DateField()
car_spaces = models.PositiveIntegerField(default=0)
fully_furnished = models.CharField(choices=fully_furnished_choices, max_length=1, default=None)
desc = models.TextField()
property_features = models.ManyToManyField(PropertyFeatures)
price = models.DecimalField(max_digits=15, decimal_places=2)
currency = models.ForeignKey(Currency, on_delete=models.CASCADE)
created_at = models.DateTimeField(auto_now_add=True)
updated_at = models.DateTimeField(auto_now=True)
Here is the forms.py
from django import forms
from .models import Listing, Property, Vehicle, Business, ListingImages
from django.forms import modelformset_factory
class ListingDetails(forms.ModelForm):
class Meta:
model = Listing
fields = ['listing_title', 'city', 'location']
class PropertyDetails1(forms.ModelForm):
class Meta:
model = Property
fields = ['sub_category', 'for_sale_rent', 'bedrooms', 'bathrooms',
'rooms', 'land_size', 'available_from', 'car_spaces', 'fully_furnished',
'desc', 'currency', 'price'
]
class PropertyDetails2(forms.ModelForm):
class Meta:
model = Property
fields = ['property_features']
class ListingImagesForm(forms.ModelForm):
image_url = forms.ImageField(label='Listing Image',
widget=forms.ClearableFileInput(attrs={'multiple': True}),
required=False
)
class Meta:
model = ListingImages
fields = ['image_url']
ImageFormSet = modelformset_factory(ListingImages, form=ListingImagesForm, extra=3)
views.py
from django.shortcuts import render, redirect
import os
from .forms import ListingDetails, PropertyDetails1, PropertyDetails2, ListingImagesForm
from .models import ListingImages, Listing, Property
from formtools.wizard.views import SessionWizardView
from django.conf import settings
from django.core.files.storage import FileSystemStorage
from django.forms import modelformset_factory
from django.contrib import messages
from django.http import HttpResponseRedirect, HttpResponse
from django.forms.models import construct_instance
class PropertyView(SessionWizardView):
# formset = ImageFormSet(queryset=Images.objects.none())
template_name = "listings/create_property.html"
form_list = [ListingDetails, PropertyDetails1, PropertyDetails2, ListingImagesForm]
file_storage = FileSystemStorage(location=os.path.join(settings.MEDIA_ROOT, 'media'))
def done(self, form_list, **kwargs):
listing_instance = Listing()
property_instance = Property()
listing_instance.created_by = self.request.user
listing_instance.listing_owner = self.request.user
listing_instance.listing_type = 'P'
for form in form_list:
listing_instance = construct_instance(form, listing_instance, form._meta.fields, form._meta.exclude)
property_instance = construct_instance(form, property_instance, form._meta.fields, form._meta.exclude)
listing = listing_instance.save()
property_instance.listing = listing
property_instance.save()
return HttpResponse('data saved successfully')
The problem that I am facing is that I am able to save the Listing model, but getting its primary id and using it to save the Property model is the problem. Again, the ListingImages model stores images related to the Listing model. How do I save these models to database considering that they are multiple?

Answer 1

What's wrong is that as described here, model.save() does not return the saved object, but None.
So the last few lines of the above code should be
listing_instance.save()
property_instance.listing = listing_instance
property_instance.save()
return HttpResponse('data saved successfully')
Ditto saving a set of listing_images would be something like
for li_obj in listing_image_instances:
li_obj.listing = listing_instance # saved above
li_obj.save()