Some lookups/transforms don't have lookup_name

[jorgecarleitao]

because RegisterLookupMixin.register_lookup requires the lookup to have a lookup_name, any transformation or lookup without it raises an AttributeError when registered.

in contrib.postgres.fields.array, some Transforms don't have lookup_name defined.

One will have to check out if we are missing any other.

[Marc Tamlyn]

IndexTransform and SliceTransform do not have lookup_name defined at the moment. However they are not designed to be registered using register_lookup at the moment. I guess this could be a reasonable use case on a third party field somehow?

Can you expand on why this is causing you a problem?

[jorgecarleitao]

I reported this when I was writing the API references of lookups. Only later I understood that only Transform and Lookup are to be registered (now documented). So, this is now more a cleanup / internals consistency than a bug. I changed it accordingly. Maybe it is not a ticket at all at the moment.

[Marc Tamlyn]

OK, I'm going to close this for now as I don't think it is an issue in this case. If someone has a genuine use case then we can add it, but I believe the way they are written means they cannot be used directly with register_lookup because their __init__ signature is wrong - you need the factory.