36. How to change ForeignKey display text in dropdowns?

Hero has a FK to Catgeory. In the dropdown, rather than just the name, you want to show the text “Category: <name>”.

You can change the __str__ method on Category, but you only want this change in the admin. You can do this by creating a subclassing forms.ModelChoiceField with a custom label_from_instance.:

class CategoryChoiceField(forms.ModelChoiceField):
     def label_from_instance(self, obj):
         return "Category: {}".format(obj.name)

You can then override formfield_for_foreignkey to use this field type for category.:

def formfield_for_foreignkey(self, db_field, request, **kwargs):
    if db_field.name == 'category':
        return CategoryChoiceField(queryset=Category.objects.all())
    return super().formfield_for_foreignkey(db_field, request, **kwargs)

Your admin look like this.

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