Django ?format doesn't work correctly in some endpoints

[jerabekjiri]

Version

pip3 list | grep -E "pulpcore|pulp-ansible|galaxy-ng"
galaxy-ng                                4.9.0.dev0
pulp-ansible                             0.19.0
pulpcore                                 3.28.14

Describe the bug
Pulp incorrectly assumes that ?format=api|json is a filter parameter instead of the django rendering format type. This issue only occurs in some endpoints.

To Reproduce
Steps to reproduce the behavior:
Visit endpoints
/pulp/api/v3/repositories/?format=api or
/pulp/api/v3/repositories/ansible/ansible/?format=json:

{
  "errors": [
    "Invalid Filter: 'format'"
  ]
}

/pulp/api/v3/repositories/?format=test:

{
  "detail": "Not found."
}

Expected behavior
Should switch between raw format and Django's pretty format, and display the data as usual.

Additional context
Discovered in ansible/galaxy_ng#1891

[jerabekjiri]

I think this can be fixed by adding format to DEFAULT_FILTERS in BaseFilterSet

pulpcore/pulpcore/filters.py

Lines 372 to 382 in bc9ca51

	def is_valid(self, *args, **kwargs):
	is_valid = super().is_valid(*args, **kwargs)
	DEFAULT_FILTERS = [
	"exclude_fields",
	"fields",
	"limit",
	"minimal",
	"offset",
	"page_size",
	"ordering",
	]

[mdellweg]

That's not even supposed to be a filter. You should user the encoding header to determine the used format. Also i'm unsure we support anything but json anyway.

[mdellweg]

https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Accept

[jerabekjiri]

@mdellweg Okay, it certainly works with accept headers, but it's still inconsistent with the format parameters. So, if pulp doesn't support text/html (?format=api), should the format parameter be completely forbidden?

Also, for https://issues.redhat.com/browse/AAH-2148, we want to use the 'pretty' format ('format=api') for the galaxy-beta. Currently, it doesn't work, and I'm wondering if this issue could be related to Pulp not supporting it and not displaying it in the production image.

[mdellweg]

Looks like both methods are supported after all:
https://www.django-rest-framework.org/topics/browsable-api/#formats

[mdellweg]

@jerabekjiri can you file your solution as a PR?
On a first glance, it looks sane to me.