Applying distinct sometimes results in errors about django-rest-framework-datatables

[izimobil]

Hi,
If the JSON returned is correct, chances are your problem is on the client side code. Maybe you're not building your Datatable correctly. Good luck.

[JackAtOmenApps]

I'm seeing the problem in both the provided example and in my own project. Before using distinct everything works, but when applying distinct things go awry.

By playing around with things I did find that the reason rank works, but year doesn't is that rank is the first column called in the table. If I filter by distinct('year') and then set columns in the DataTable like this:

"columns": [
    {"data": "year"},
    {"data": "rank", "searchable": false},
    // Use dot notation to reference nested serializers.
    // This data: could alternatively be displayed with the serializer's ReadOnlyField as well, as seen in the minimal example.
    {"data": "artist.name", "name": "artist.name"},
    {"data": "name"},
    {"data": "genres", "name": "genres.name", "sortable": false},
],

then I get a valid DataTable. Whatever field is distinct must be the first field called in the table. The I can use ColReorder to move the columns around as needed.

The problem now is that while I get a table now, I can ONLY sort by the column that is distinct. Attempting to sort by any other column (using the table headers) returns ajax errors, both in the (modified) example project and in my own project.

[JackAtOmenApps]

I seem to have found a solution, though I don't know why it works.

If I change:

class AlbumViewSet(viewsets.ModelViewSet):
    queryset = Album.objects.all().order_by('year', 'rank').distinct('year')

    serializer_class = AlbumSerializer

to:

class AlbumViewSet(viewsets.ModelViewSet):
    album = Album.objects.all().order_by('year').distinct('year')
    queryset = Album.objects.filter(id__in=album)

    serializer_class = AlbumSerializer

... all works perfectly! Sorting, filtering, etc all work now. An extra query is required, but it's worth it. Still not sure why simply applying distinct fails to work properly, but I can live with this modification