'invalid_choice' in field foreing key django - django

Question

I have a problem with a foreing key field that I initialize with a queryset, the form is displayed but at the time of sending data the error 'in to_python raise ValidationError (self.error_messages [' invalid_choice '], code =' invalid_choice ')' appears' .
I know there is a way to invalidate the 'to_python' method but I still can not get it to work. I would appreciate any help.
My view:
class PlanesCreate(generic.CreateView):
model= Plan_Estudios
template_name= 'ControlEscolar/Administracion/planes/planes_form.html'
form_class= PlanForm
success_url = reverse_lazy('ControlEscolar:planes_filtro')
def get_form_kwargs(self):
kwargs = super(PlanesCreate, self).get_form_kwargs()
kwargs.update({'programa': self.request.session['programa']})
return kwargs
My form:
class PlanForm(forms.ModelForm):
class Meta:
model = Plan_Estudios
fields = "__all__"
widgets = {
'nombreplan': forms.TextInput(attrs={'class':'form-control'}),
'programa': forms.Select(attrs={'class':'form-control'}),
}
def __init__(self, *args, **kwargs):
p=kwargs.pop('programa', None)
super(PlanForm, self).__init__(*args, **kwargs)
query=Programa_Academico.objects.filter(pk=p)
self.fields['programa'].queryset=query #Inicialize field with query
My model:
class Plan_Estudios(models.Model):
nombreplan= models.CharField(max_length=30)
programa= models.ForeignKey(Programa_Academico, on_delete=models.SET_NULL, null=True)
def __str__(self):
return self.nombreplan
class Programa_Academico(models.Model):
nombreP= models.CharField(max_length=50)
siglas= models.CharField(max_length=10)
def __str__(self):
return self.siglas
Error:
File "C:\Users\Envs\py1\lib\site-packages\django\forms\forms.py" in is_valid
185. return self.is_bound and not self.errors
File "C:\Users\Envs\py1\lib\site-packages\django\forms\forms.py" in errors
180. self.full_clean()
File "C:\Users\Envs\py1\lib\site-packages\django\forms\forms.py" in full_clean
381. self._clean_fields()
File "C:\Users\Envs\py1\lib\site-packages\django\forms\forms.py" in _clean_fields
399. value = field.clean(value)
File "C:\Users\Envs\py1\lib\site-packages\django\forms\fields.py" in clean
147. value = self.to_python(value)
File "C:\Users\Envs\py1\lib\site-packages\django\forms\models.py" in to_python
1252.
raise ValidationError(self.error_messages['invalid_choice'],
code='invalid_choice')
Exception Type: KeyError at /ControlEscolar/planes/crear
Exception Value: 'invalid_choice'