[FIXED] How to filter a ManyToMany query in a class based view?

Issue

I have the following models:

class List(models.Model):
    participants = models.ManyToManyField(Participant, through='ParticipantThroughModel', blank=True)

class ParticipantThroughModel(models.Model):
    participantlist = models.ForeignKey(List, null=True, on_delete=models.PROTECT)
    participants = models.ForeignKey(Participant, null=True, on_delete=models.PROTECT)
    is_responsible_person = models.BooleanField()

class Participant(models.Model):
    username = models.CharField(max_length=255)

And I have the following view:

class ListDetail(DetailView):
    model = List
    template_name = 'participantlists/participantlist_detail.html'
    context_object_name = 'participantlist

In my template, I can display all the Participant via:

{% for obj in participantlist.participantthroughmodel_set.all %}
{{ obj.participants }}
{% endfor %}

However, if I want to filter this to display both this code with all participants and another for loop showing only participants with is_responsible_person = True how can I do this?

Solution

You can filter the queryset in the view, by overriding the get_context_data(…) method ^[Django-doc]:

class ListDetail(DetailView):
    model = List
    template_name = 'participantlists/participantlist_detail.html'
    context_object_name = 'participantlist'

    def get_context_data(self, **kwargs):
        result = super().get_context_data()
        result.update(
            participants=self.object.participantthroughmodel_set.filter(is_responsible_person=True)
        )
        return result

in the template, you then can iterate over participants:

{% for obj in participants %}
    {{ obj.participants }}
{% endfor %}

Answered By - Willem Van Onsem