Django Image by Foreign Key and {% if / else %} - django

Question

I trying to access the ImageField of a Model which is assigned via ForeignKey to another Model.
I have different Animal Apps in my Projects, with almost the same structure, like the following models.py. On the landingpage of My Project I want to display the last 3 entry of every (Species) Models with Name and Picture. If the Species has no Picture I would like to display the ImageField of the Farm, which is connected via ForeignKey to my species.
cows/models.py
class Farm(models.Model):
name = models.CharField(max_length=100)
farm_img = models.ImageField(upload_to='farm_images/',
max_length=255, null=True, blank=True)
class Cows(models.Model):
farm = models.ForeignKey(Farm, on_delete=models.CASCADE, null=True)
name = models.CharField(max_length=100)
entry_date = models.DateField(null=True, blank=True)
cow_img = models.ImageField(upload_to='farm_images/',
max_length=255, null=True, blank=True)
Views.py
class HomeIndex(TemplateView):
template_name = 'home.html'
def get_context_data(self, **kwargs):
context['chickens'] = Chicken.objects.order_by('-entry_date')[:3]
context['cows'] = Cows.objects.order_by('-entry_date')[:3]
context['cats'] = Cats.objects.order_by('-entry_date')[:3]
return context
home.html
<….>
{% for somecow in cows %}
<div class="col-3" id="p1">
<h2>{{ somecow.name }}</h2>
<h2>{{ somecow.entry_date }}</h2>
{% if somecow.cow_img %}
<img src="{{ somecow.cow_img.url }}" alt="Mod" height="100">
{% endif %}
</div>
{% endfor %}
<….>
Until here it worked.
But how can i access the FK.Model of the Model?
Or in other Words how can I tell Django:
“If you found no cow Picture in Cow.Model,then show a Farm picture from the assigned Farm.Model?”
As I understand I can access the assigned FK Models via
{% for something in MyModel1.MyModel2_set.all %}.
my approach for home.html
<….>
{% for somecow in cows %}
<div class="col-3" id="p1">
<h2>{{ somecow.name }}</h2>
<h2>{{ somecow.entry_date }}</h2>
{% if somecow.cow_img %}
<img src="{{ somecow.cow_img.url }}" alt="Mod" height="100">
{% else %}
{% for farm in somecow.farm_set.all %}
{% if farm.farm_img %}
<img src="{{ farm.farm_img.url }}" alt="Mod" height="100">
{% endif %}
{% endfor %}
{% endif %}
</div>
{% endfor %}
<….>
So far I received no error Message, but I also see no Farm Image. I am sure I mixed something up in home.html. On the other Side I think I maybe I missed something in my view, something like MyModel.objects.all()
I am thankful for every hint.

Answer 1

You're overcomplicating things. There is only a single farm per cow: you just need to access it directly.
{% else %}
{% if cow.farm.farm_img %}
<img src="{{ cow.farm.farm_img.url }}" alt="Mod" height="100">
{% endif %}
{% endif %}