[Django]-Creating a dynamic choice field

205πŸ‘

βœ…

you can filter the waypoints by passing the user to the form init

class waypointForm(forms.Form):
    def __init__(self, user, *args, **kwargs):
        super(waypointForm, self).__init__(*args, **kwargs)
        self.fields['waypoints'] = forms.ChoiceField(
            choices=[(o.id, str(o)) for o in Waypoint.objects.filter(user=user)]
        )

from your view while initiating the form pass the user

form = waypointForm(user)

in case of model form

class waypointForm(forms.ModelForm):
    def __init__(self, user, *args, **kwargs):
        super(waypointForm, self).__init__(*args, **kwargs)
        self.fields['waypoints'] = forms.ModelChoiceField(
            queryset=Waypoint.objects.filter(user=user)
        )

    class Meta:
        model = Waypoint
πŸ‘€Ashok

13πŸ‘

There’s built-in solution for your problem: ModelChoiceField.

Generally, it’s always worth trying to use ModelForm when you need to create/change database objects. Works in 95% of the cases and it’s much cleaner than creating your own implementation.

8πŸ‘

the problem is when you do

def __init__(self, user, *args, **kwargs):
    super(waypointForm, self).__init__(*args, **kwargs)
    self.fields['waypoints'] = forms.ChoiceField(choices=[ (o.id, str(o)) for o in Waypoint.objects.filter(user=user)])

in a update request, the previous value will lost!

πŸ‘€Liang

4πŸ‘

How about passing the rider instance to the form while initializing it?

class WaypointForm(forms.Form):
    def __init__(self, rider, *args, **kwargs):
      super(joinTripForm, self).__init__(*args, **kwargs)
      qs = rider.Waypoint_set.all()
      self.fields['waypoints'] = forms.ChoiceField(choices=[(o.id, str(o)) for o in qs])

# In view:
rider = request.user
form = WaypointForm(rider) 

4πŸ‘

You can declare the field as a first-class attribute of your form and just set choices dynamically in __init__:

class WaypointForm(forms.Form):
    waypoints = forms.ChoiceField(choices=[])

    def __init__(self, user, *args, **kwargs):
        super().__init__(*args, **kwargs)
        waypoint_choices = [(o.id, str(o)) for o in Waypoint.objects.filter(user=user)]
        self.fields['waypoints'].choices = waypoint_choices

This approach also works with a ModelChoiceField.

This approach is superior if you are using a ModelForm, and want to override choices of an autogenerated field.

πŸ‘€Zags

3πŸ‘

If you need a dynamic choice field in django admin; This works for django >=2.1.

class CarAdminForm(forms.ModelForm):
    class Meta:
        model = Car

    def __init__(self, *args, **kwargs):
        super(CarForm, self).__init__(*args, **kwargs)

        # Now you can make it dynamic.
        choices = (
            ('audi', 'Audi'),
            ('tesla', 'Tesla')
        )

        self.fields.get('car_field').choices = choices

    car_field = forms.ChoiceField(choices=[])

@admin.register(Car)
class CarAdmin(admin.ModelAdmin):
    form = CarAdminForm

Hope this helps.

πŸ‘€Tobias Ernst

2πŸ‘

Underneath working solution with normal choice field.
my problem was that each user have their own CUSTOM choicefield options based on few conditions.

class SupportForm(BaseForm):

    affiliated = ChoiceField(required=False, label='Fieldname', choices=[], widget=Select(attrs={'onchange': 'sysAdminCheck();'}))

    def __init__(self, *args, **kwargs):

        self.request = kwargs.pop('request', None)
        grid_id = get_user_from_request(self.request)
        for l in get_all_choices().filter(user=user_id):
            admin = 'y' if l in self.core else 'n'
            choice = (('%s_%s' % (l.name, admin)), ('%s' % l.name))
            self.affiliated_choices.append(choice)
        super(SupportForm, self).__init__(*args, **kwargs)
        self.fields['affiliated'].choices = self.affiliated_choice
πŸ‘€Deil

1πŸ‘

As pointed by Breedly and Liang, Ashok’s solution will prevent you from getting the select value when posting the form.

One slightly different, but still imperfect, way to solve that would be:

class waypointForm(forms.Form):
    def __init__(self, user, *args, **kwargs):
        self.base_fields['waypoints'].choices = self._do_the_choicy_thing()
        super(waypointForm, self).__init__(*args, **kwargs)

This could cause some concurrence problems, though.

πŸ‘€Haroldo_OK

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