Boolean Filter on Django Admin - django

Question

I'm trying to build a filter that corresponds to the has_images method on my Django admin, but I can't because it strictly says that has_images is not a field of the model. I tried setting it up as a property, but it also didn't work.
I thought about defining has_images as a field and really calculating it, based on the changes on the model, but I think that would be not optimal.
What would be a good solution here?
models.py
class Product(models.Model):
name = models.CharField("Name", max_length=255)
def has_images(self):
return self.images.all().count() > 0
has_images.boolean = True
class ProductImage(models.Model):
product = models.ForeignKey(Product, on_delete=models.CASCADE, related_name="images")
file = models.ImageField("Product Image")
admin.py
class ProductImageInline(admin.TabularInline):
model = ProductImage
fields = ('file',)
extra = 1
class ProductAdmin(VersionAdmin):
list_display = ('id', 'name', 'has_images',)
inlines = (ProductImageInline,)
Expected result:

Answer 1

Can you share the contents of the admin.py file?
Or let me explain it as follows. Add a feature called list_filter = ('images') into the ProductAdmin class you created in admin.py. If this feature doesn't work (I'm not sure as I haven't tried it), if you create an Admin Class for ProductImages directly, you can already view the pictures and the corresponding Product on that page.
----------- EDIT ----------------
This is how I solved the problem.
models.py
from django.db import models
class Product(models.Model):
name = models.CharField("Name", max_length=255)
is_image = models.BooleanField(default=False, editable=False)
def save(self, *args, **kwargs):
if self.images.count():
self.is_image = True
else:
self.is_image = False
super(Product, self).save(*args, **kwargs)
class ProductImage(models.Model):
product = models.ForeignKey(Product, on_delete=models.CASCADE, related_name="images")
file = models.ImageField("Product Image")
def save(self, *args, **kwargs):
super(ProductImage, self).save(*args,**kwargs)
self.product.save()
admin.py
from django.contrib import admin
from .models import *
class ProductImageInline(admin.TabularInline):
model = ProductImage
fields = ('file',)
extra = 1
class ProductAdmin(admin.ModelAdmin):
list_display = ('id', 'name',)
list_filter = ('is_image',)
inlines = (ProductImageInline,)
admin.site.register(Product, ProductAdmin)
Here I added an is_image BooleanField field with False by default. Every time the save method of the Product model runs, it checks whether there is an image in the ProductImage to which the Product model is attached. If there is an image in it, is_image is set as True.