Validate multiple related objects through foreign key field in Django ModelForm

Question

In the example shown by the code below, is it possible to automatically validate and create instances of Endereco and Coordenada using LocalizacaoForm?

The reason why I want to do this is so that I can use Generic Views as much as possible, and they don't work well (at least not out-of-the-box) with more than one ModelForm per view.

In the application, I want to render a LocalizacaoForm and show the fields from Endereco and Coordenada as well. What I am doing in so far doesn't seem to solve it, because self.fields.update(fields_for_model(Coordenada)) only creates the input fields, not an actual instance of Coordenada. Therefore I get a django NOT NULL constraint failed id for the object coordenada.

Is there a way to do what I want or should I just stick with rendering each form separately?

#models.py
class Coordenada(models.Model):
    latitude = models.FloatField()
    longitude = models.FloatField()
    altitude = models.FloatField()
    erro_horizontal = models.FloatField()

class Endereco(models.Model):
    cep = models.IntegerField()
    uf = models.CharField(max_length=2)
    localidade = models.CharField(max_length=50)  # nome da cidade
    # other fields...

class Localizacao(models.Model):
    endereco = models.OneToOneField(Endereco)
    coordenada_geografica = models.ForeignKey('Coordenada')

#forms.py
class LocalizacaoForm(forms.ModelForm):

    def __init__(self, instance=None, *args, **kwargs):
        super(LocalizacaoForm, self).__init__(instance=instance, *args, **kwargs)
        # Retrieve the fields from Endereco and Coordenada model and update the fields with it
        self.fields.update(fields_for_model(Endereco))
        self.fields.update(fields_for_model(Coordenada))

    class Meta:
        model = Localizacao
        exclude = ('endereco', 'coordenada_geografica')

#views.py
class LocalizacaoCreateView(generic.CreateView):
    model = Localizacao
    form_class = LocalizacaoForm
    template_name = 'localizacao_create_form.html'

xyres · Accepted Answer · 2016-02-27 09:25:38Z

2

You can create instances of Coordenada and Endereco in the save() method of LocalizacaoForm, like this:

class LocalizacaoForm(forms.ModelForm):

    # The rest of the form ...
    # ...

    def save(self, commit=False):
        localizacao = super(LocalizacaoForm, self).save(commit=False)

        # create an instance of Coordenada
        coordenada = Coordenada.objects.create(
                        latitude=self.cleaned_data['latitude'],
                        longitude=self.cleaned_data['longitude'],
                        altitude=self.cleaned_data['altitude'],
                        erro_horizontal=self.cleaned_data['erro_horizontal']
                    )

        # create an instance of Endereco
        endereco = Endereco.objects.create(
                        cep=self.cleaned_data['cep'],
                        uf=self.cleaned_data['uf'],
                        localidade=self.cleaned_data['localidade'],
                    )

        # add those instances to localizacao
        localizacao.coordenada_geografica = coordenada
        localizacao.endereco = endereco

        if commit:
            localizacao.save()
        return localizacao

answered Feb 27, 2016 at 9:25

xyres

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1 Comment

Hannon Queiroz Over a year ago

Works like a charm and looks much cleaner than if I had created the each form separately. Thanks!

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