Add m2m_changed signal

[KengoWada]

Problem Statement

Take the following models:

# models.py
class Artist(models.Model):
    name = models.CharField(max_length=100)
    ...

class Song(TypesenseModelMixin)
    ...
    artists = models.ManyToManyField(Artist)
    collection_class = SongCollection

    def artists_names(self):
        return list(self.artists.all().values_list('name', flat=True))

When a new song is created and then an artist is added, it does not save the artist's name to TypeSense and when querying it returns an empty list.

artist = Artist.objects.create(name='J Cole')
song = Song.objects.create(name='Fire Squad')
song.artists.add(artist)

In this case, only the post_save_typesense_models is hit after the creation of the song which has an empty list of artists and after the artist is added(or removed) to the song it doesn't reflect in TypeSense.

Solution

• Add a m2m_changed signal
• Consider the post_add, post_remove and post_clear actions

[KengoWada]

Hey @EricOuma please assign this to me. Thanks

[EricOuma]

@KengoWada There is some problem with the implementation of this. Here is how to reproduce:

class Library(models.Model)
    songs = models.ManyToManyField(Song)

This will eventually try calling Library.get_collection(instance).update()

Your fix might look like this:

@receiver(m2m_changed)
def m2m_changed_typesense_models(instance, model, action, reverse, **kwargs):
    if action in ["post_add", "post_remove", "post_clear"]:
        if reverse and issubclass(model, TypesenseModelMixin):
            pk_set = list(kwargs.get("pk_set"))
            obj = model.objects.filter(pk__in=pk_set)
            model.get_collection(obj=obj, many=True).update()
        else:
            if isinstance(instance, TypesenseModelMixin):
                instance_class = instance.__class__
                instance_class.get_collection(instance).update()

[EricOuma]

@KengoWada It's a bit urgent so let me know if you are able to work on it today

[KengoWada]

@EricOuma let me work on it now.

[EricOuma]

@KengoWada Did you try testing with the sample model I gave?

library.songs.add(...) does not work as expected

class Song(TypesenseModelMixin):
     ...
    @property
    def library_ids(self):
        return list(self.libraries.values_list('id', flat=True))

class Library(models.Model)
    songs = models.ManyToManyField(Song, related_name='libraries')

class SongCollection(TypesenseCollection):
    ...
    library_ids = fields.TypesenseArrayField(base_field=fields.TypesenseSmallIntegerField(), value='library_ids')

[KengoWada]

Hey @EricOuma I only run the existing tests. I have seen the issue. Let me work on a fix.