Pulp

The Importer model is an example of the existing master/detail model in Pulp3.
The same issue is relevant for the Publisher model or any other master/detail model.

Currently there are endpoints for the detail models only:

 ^api/v3/ ^repositories/(?P<repository_name>[^/.]+)/importers/basicfile/$
 ^api/v3/ ^repositories/(?P<repository_name>[^/.]+)/importers/file/$

The type of importer has to be always specified and the following endpoint doesn't exist (results in 404):

 ^api/v3/ ^repositories/(?P<repository_name>[^/.]+)/importers/$

Decide and agree on what the missing endpoint should do.
Suggest a solution (what kind of changes has to be made for model/serializer/viewset classes).

IRC discussion:

[20:27:53] <ttereshc> It's confusing from the user standpoint that they need to specify importer type, imho
[20:28:22] <mhrivnak> ttereshc it's a known limitation of the master/detail feature.
[20:29:27] <mhrivnak> ttereshc I think it might only matter when trying to add an importer. Do you think that's correct?
[20:29:42] <mhrivnak> You should be able to read the importers from the repository representation.
[20:30:05] <asmacdo> I want an endpoint for /api/v3/repositories/<repo_id>/importers/  that lists the types
[20:31:23] <ttereshc> mhrivnak, yeah, for me it makes sense to specify type when you create an importer and yes you can get all the importers from the repo representation, but I'd expect importers/ endpoint to list all importers (currently one per repo)
[20:31:34] <mhrivnak> asmacdo I kinda agree, but that's not what you'd expect at an importers/ endpoint
[20:32:29] <asmacdo> the trouble with listing all importers is that they would not all share the same serializer
[20:34:01] <asmacdo> Although, now that we have named serializers, we might be able to use that in combination with cast()