Postgres ArrayField doesn't work properly.

[creative3000]

When you filter by len like in documentation example:

  Post.objects.filter(tags__len=1)

But if you try to annotate something an error pops up example:

 Post.objects.all().annotate(tag_len=F('tags__len'))

It really seems that it should work by default, but instead I needed to use something like this

 Post.objects.all().annotate(tag_len=Func(F('tags'), 1, function='array_length'))