How to customize/filter django admin panel forms data?

Question

I created models as below; Team model stores different team names, Tournament model is used to create a tournament and add teams into it and finally Game model where I select a tournament, add two teams and create a game. My problem is in Admin panel, while creating a game after selecting a tournament I have to select two teams from the choice list, instead of getting just the teams participating in the Tournament, I am getting all the available teams from the Team model.

class Team(models.Model):
    name = models.CharField(max_length=30) # Ind, Pak, Aus, Sri, Eng

class Tournament(models.Model):
    name = models.CharField(max_length=50) # Asia Cup:
    teams = models.ManyToManyField(Team)  # Ind, Pak, Sri

class Game(models.Model):
    name = models.CharField(max_length=50)
    tournament = models.ForeignKey(Tournament, on_delete=models.CASCADE) # Asia Cup
    teams = models.ManyToManyField(Team) # Expected: Ind, Pak, Sri

My Admin panel customization:

class TeamInline(admin.TabularInline):
    model = Game.teams.through

class Game(admin.ModelAdmin):
    fields = ['name']
    inlines = [TeamInline]

Answer 1

Django Admin Inline use ModelForm to render it's content(described in doc ) so you need to override the child form .

After that set custom formset to pass parent to child form, and in the child form override initial value with init within form doc

class TeamInlineCustomFormSet(BaseInlineFormSet):
    def get_form_kwargs(self, index):
        kwargs = super().get_form_kwargs(index)
        kwargs['parent_object'] = self.instance
        return kwargs

class TeamInlineCustomForm(forms.ModelForm):
    def __init__(self, *args, parent_object, **kwargs):
        self.parent_object = parent_object
        super (TeamInlineCustomForm, self).__init__(*args, **kwargs)
        if parent_object: # check if has game instance
            self.fields['team'].queryset = parent_object.tournament.teams.all()
       
    class Meta:
        model = Game.teams.through

class TeamInline(admin.TabularInline):
    model = Game.teams.through
    
    formset = TeamInlineCustomFormSet
    form = TeamInlineCustomForm

• this custom filtered queryset only work with edit form of the game(doesn't work on create game, it will show all teams)
• parent_object refer to the Game instance when you editing

the way to get parent instance in Inline Admin Form come from this answer