ModelForm : pass the object's id as extra parameter in AJAX call

Hi !

I have a Team model and a Member model. The Team model has a captain field.

Now, in my ModelForm, for the captain field, I want to filter the autocomplete to show only members of the team that I’m editing. This means I need to pass a team_id parameter alongside the q parameter.

I think it’s a fairly commun scenario, just like forward=['continent']. I googled the issue and found some links, but they all are quite complex hacks combining advanced django and javascript, and I couldn’t make them work (I’m no javascript expert).

I’d suggest either :

• add an option like forward but to send the modelform’s instance’s pk instead
• document the easiest way to get that result

Thanks a lot for the awesome module !

[toudi]

Ok, chaps, sorry for the long delay, I couldn’t get to the computer.

Anyways, I think this turned out to be pretty easy problem (or am I this naive?). Here it goes:

# the models:
class Team(models.Model):
    name = models.CharField(max_length=255)
    captain = models.OneToOneField(
        'team.TeamMember',
        related_name='+',
        null=True,
        blank=True
    )

    def __unicode__(self):
        return self.name


class TeamMember(models.Model):
    team = models.ForeignKey('team.Team')
    name = models.CharField(max_length=32)

    def __unicode__(self):
        return '%s/%s' % (self.team.name, self.name)

# the forms:
from django import forms
from team.models import Team
from dal import autocomplete


class TeamForm(forms.ModelForm):
    team_id = forms.IntegerField(
        required=False, widget=forms.HiddenInput)

    def __init__(self, *args, **kwargs):
        instance = kwargs.get('instance', None)
        if instance:
            kwargs['initial'] = {'team_id': instance.pk}

        super(TeamForm, self).__init__(*args, **kwargs)

    class Meta:
        model = Team
        widgets = {
            'captain': autocomplete.ModelSelect2(
                url='team-member-autocomplete',
                forward=['team_id']
            )
        }
        exclude = []

    def clean_captain(self):
        captain = self.cleaned_data.get('captain')

        if captain and captain.team_id != self.instance.id:
            raise forms.ValidationError("Invalid captain for this team!")

        return captain

# the views
from dal import autocomplete
from team.models import TeamMember


class TeamMemverAutocomplete(autocomplete.Select2QuerySetView):
    def get_queryset(self):
        # Don't forget to filter out results depending on the visitor !

        team_id = self.forwarded['team_id']

        if not team_id:
            return TeamMember.objects.none()

        qs = TeamMember.objects.filter(team_id=team_id)

        if self.q:
            qs = qs.filter(name__icontains=self.q)

        return qs

# the admin:
from django.contrib import admin
from team.models import Team, TeamMember
from team.forms import TeamForm


class TeamAdmin(admin.ModelAdmin):
    form = TeamForm


admin.site.register(Team, TeamAdmin)
admin.site.register(TeamMember)

I don’t know if this is the desired result for @olivierdalang , however this works in the following way:

1. It autocompletes the captain based on selected team ID
2. It only does so if a team is being edited (no results will be given on team creation)
3. Even if somebody manages to change the team id, validationerror is thrown.

yours truly,

[toudi]

this looks like an interesting problem. I’ll try tackling it, probably during the night.

cheers, m.