Populate combos in Django and initialize them with a foreign key - django

Question

I need to populate two combos in a ModelForm, and I would like to initialize them with the current value of each foreign key.
My models are:
class Alumno(models.Model):
idalumno = models.AutoField(primary_key=True)
padre_idpadre = models.ForeignKey('Padre', models.DO_NOTHING, db_column='padre_idpadre', blank=True, null=True)
curso_idcurso = models.ForeignKey('Curso', models.DO_NOTHING, db_column='curso_idcurso')
nombre = models.CharField(max_length=45, blank=True, null=True)
class Meta:
db_table = 'alumno'
class Curso(models.Model):
idcurso = models.IntegerField(primary_key=True)
nombrecurso = models.CharField(max_length=45, blank=True, null=True)
class Meta:
db_table = 'curso'
class Padre(models.Model):
idpadre = models.AutoField(primary_key=True)
socio = models.NullBooleanField(blank=True, null=True)
nombre = models.CharField(max_length=45, blank=True, null=True)
primerapellido = models.CharField(max_length=45, blank=True, null=True)
segundoapellido = models.CharField(max_length=45, blank=True, null=True)
class Meta:
db_table = 'padre'
This is my Form in forms.py:
class AlumnoForm(forms.ModelForm):
padre = PadreModelChoiceField(queryset=Padre.objects.all(), initial=**XXXXXXXXX**) #I would like to init here with the value of the FK
curso = CursoModelChoiceField(queryset=Curso.objects.all(), initial=**XXXXXXXXXX**) #And here too
class Meta:
model = Alumno
fields = ('nombre','padre','curso',)
labels = {
'nombre': 'Nombre',
'padre': 'Padre',
'curso': 'Curso',
}
In views.py
def alumno_editar(request, pk):
alumno = get_object_or_404(Alumno, pk=pk)
if request.method == "POST":
form = AlumnoForm(request.POST, instance=alumno)
if form.is_valid():
alumno = form.save(commit=False)
alumno.save()
return redirect('alumno_listar')
else:
form = AlumnoForm(instance=alumno)
return render(request, 'administration/alumno_editar.html', {'form': form})
What should I write in the part XXXXXXXXXX of the code.
It could be misconception but I'm think is a common operation, althought I don't find it.