Associate classes with django-filters

Bonjour, I have a question regarding django-filters. My problem is:
I have two classes defined in my models.py that are:

class Volcano(models.Model):
vd_id = models.AutoField("ID, Volcano Identifier (Index)",
primary_key=True)
[...]

class VolcanoInformation(models.Model):

# Primary key
vd_inf_id = models.AutoField("ID, volcano information identifier (index)",
primary_key=True)

# Other attributes
vd_inf_numcal = models.IntegerField("Number of calderas")
[...]

# Foreign key(s)
vd_id = models.ForeignKey(Volcano, null=True, related_name='vd_inf_vd_id',
on_delete=models.CASCADE)


The two of them are linked throught the vd_id attribute.

I want to develop a search tool that allows the user to search a volcano by its number of calderas (vd_inf_numcal).

I am using django-filters and for now here's my filters.py:

from .models import *
import django_filters

class VolcanoFilter(django_filters.FilterSet):

vd_name = django_filters.ModelChoiceFilter(
queryset=Volcano.objects.values_list('vd_name', flat=True),
widget=forms.Select, label='Volcano name',
to_field_name='vd_name',
)

vd_inf_numcal = django_filters.ModelChoiceFilter(
queryset=VolcanoInformation.objects.values_list('vd_inf_numcal', flat=True),
widget=forms.Select, label='Number of calderas',
)


class Meta:
model = Volcano
fields = ['vd_name', 'vd_inf_numcal']


My views.py is:

def search(request):
feature_list = Volcano.objects.all()
feature_filter = VolcanoFilter(request.GET, queryset = feature_list)

return render(request, 'app/search_list.html', {'filter' : feature_filter, 'feature_type': feature_type})


In my application, a dropdown list of the possible number of calderas appears but the search returns no result which is normal because there is no relation between VolcanoInformation.vd_inf_numcal, VolcanoInformation.vd_id and Volcano.vd_id.

It even says "Select a valid choice. That choice is not one of the available choices."

My question is how could I make this link using django_filters ?
I guess I should write some method within the class but I have absolutely no idea on how to do it.

If anyone had the answer, I would be more than thankful !

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