Django Admin formfield_for_foreignkey for manytomany - django

Question

My Model (simpliefied)
we have tours:
class Tour(models.Model):
name = models.CharField(max_length=100)
strecke = models.ManyToManyField(Strecke, through="Streckenreihenfolge")
A tour has sections:
class Strecke(models.Model):
name = models.CharField(max_length=100)
auftrag = models.ForeignKey("Auftrag", on_delete=models.CASCADE, null=True, blank=True)
And the sections are put in order
class Streckenreihenfolge(models.Model):
strecke = models.ForeignKey(Strecke, on_delete=models.CASCADE)
tour = models.ForeignKey("Tour", on_delete=models.CASCADE)
reihenfolge = models.IntegerField()
In my admin, I want to give some restrictions on which sections (Strecke) to show. I thought about using formfield_for_foreignkey. It gets called, but it doesn't have any impact on the options to select from:
#admin.register(Tour)
class TourAdmin(admin.ModelAdmin):
class StreckenreihenfolgeAdminInline(admin.TabularInline):
model = Streckenreihenfolge
autocomplete_fields = ["strecke"]
ordering = ["reihenfolge"]
extra = 0
def formfield_for_foreignkey(self, db_field, request, **kwargs):
print(db_field.name)
if db_field.name == 'strecke':
kwargs['queryset'] = Strecke.objects.filter(auftrag_id__exact=8)
return super().formfield_for_foreignkey(db_field, request, **kwargs)
inlines = [StreckenreihenfolgeAdminInline, ]
Does formfield_for_foreignkey not work for manytomanyfields?
Update
Found some more infos here: Django Admin - Filter ManyToManyField with through model
Apparently formfield_for_manytomany doesn't work for inline forms.
I have then tried to use get_queryset(), which reduced the queryset, but somehow the autocomplete values are still unfiltered.
Maybe this image here is illustrating more what I'm try to achieve:

Answer 1

Finally found the answer here: https://forum.djangoproject.com/t/django-admin-autocomplete-field-search-customization/7455/5
Which results in the following code:
#admin.register(Strecke)
class StreckeAdmin(admin.ModelAdmin):
search_fields = ["name"]
def get_search_results(self, request, queryset, search_term):
print("get serach results")
queryset = queryset.filter(auftrag_id__exact=8)
qs = super().get_search_results(request, queryset, search_term)
print(qs)
return qs