Django-rest-framework "groupby" Modelserializer

I have the following situation class MyModel(models.Model): key = models.CharField(max_length=255) value = models.TextField(max_length=255) category = models.CharField(

Solution 1:

There is module that allows you to group Django models and still work with a QuerySet in the result: https://github.com/kako-nawao/django-group-by

Using the above to form your queryset:

# Postgres specific!from django.contrib.postgres.aggregates.general import ArrayAgg

qs = MyModel.objects.group_by('key', 'category').annotate(
        mode_list=ArrayAgg('mode')).order_by(
        'key', 'category').distinct()

You can then access the properties key, category and mode_list on the resulting QuerySet items as attributes like qs[0].mode_list. Therefore, in your serializer you can simply name them as fields.

The model_list field might require a SerializerMethodField with some custom code to transform the list.

Note that you need an aggregation if you don't want to group by mode, as well.