Users should be able to configure API renderer_classes

[narun4sk]

Issue Summary

Users should be able to configure API renderer_classes, currently these are hardcoded to [JSONRenderer, BrowsableAPIRenderer]:

wagtail/wagtail/api/v2/views.py

Line 26 in 1958bba

renderer_classes = [JSONRenderer, BrowsableAPIRenderer]

Steps to Reproduce

Configure pages endpoint as usual, but do not include rest_framework in the INSTALLED_APPS. Try to open configured endpoint in the browser, the app will throw an exception:

Internal Server Error: /rest/p/
Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/django/core/handlers/exception.py", line 34, in inner
    response = get_response(request)
  File "/usr/local/lib/python3.8/site-packages/django/core/handlers/base.py", line 145, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/usr/local/lib/python3.8/site-packages/django/core/handlers/base.py", line 143, in _get_response
    response = response.render()
  File "/usr/local/lib/python3.8/site-packages/django/template/response.py", line 105, in render
    self.content = self.rendered_content
  File "/usr/local/lib/python3.8/site-packages/rest_framework/response.py", line 70, in rendered_content
    ret = renderer.render(self.data, accepted_media_type, context)
  File "/usr/local/lib/python3.8/site-packages/rest_framework/renderers.py", line 723, in render
    template = loader.get_template(self.template)
  File "/usr/local/lib/python3.8/site-packages/django/template/loader.py", line 19, in get_template
    raise TemplateDoesNotExist(template_name, chain=chain)
django.template.exceptions.TemplateDoesNotExist: rest_framework/api.html

Technical details

• Python Version: 3.8.2
• Django Version: 3.0
• Wagtail Version: 2.9

---

Currently I'm using this nasty trick:

from django.conf import settings
from wagtail.api.v2.views import PagesAPIViewSet
from wagtail.api.v2.router import WagtailAPIRouter

if not settings.DEBUG:
    from rest_framework.renderers import JSONRenderer

    class ProdPagesAPIViewSet(PagesAPIViewSet):
        renderer_classes = [JSONRenderer]

    PagesAPIViewSet = ProdPagesAPIViewSet

# Create the router. "wagtailapi" is the URL namespace
api_router = WagtailAPIRouter("wagtailapi")

api_router.register_endpoint("p", PagesAPIViewSet)

[marteinn]

Thanks for filing an issue @narun4sk! How would you envision the api for setting “rendered_classes”? I think creating a subclass and overriding “rendered_classes” is the way you would do it in DRF as well.

[phptek]

I've been looking to do something very similar myself, without copy-pasting all the Wagtail page-specific renderer logic into a subclass. Tried with JSON+HAL last week using https://github.com/seebass/drf-hal-json/ but just couldn't get it to work.

I'm going to try with JSON:API next, but imagine I will encounter the same underlying modification problems (See: https://github.com/django-json-api/django-rest-framework-json-api). Maybe some docs that describe how developers might go about modifying the Wagtail-specific JSON format? That would help heaps :-)

[narun4sk]

@marteinn in DRF we have this luxury in settings like:

REST_FRAMEWORK = {
    "DEFAULT_RENDERER_CLASSES": [
        "rest_framework.renderers.JSONRenderer",
    ],
}

IMO it's not too difficult to implement the same idea, isn't it? 🤔

Something like:

WAGTAIL_API = {
    "DEFAULT_RENDERER_CLASSES": [
        "rest_framework.renderers.JSONRenderer",
        "rest_framework.renderers.BrowsableAPIRenderer",
    ],
}

Then if I don't like the defaults I would just set:

WAGTAIL_API["DEFAULT_RENDERER_CLASSES"] = ["rest_framework.renderers.JSONRenderer"]

[marteinn]

Many thanks @narun4sk and @phptek. This is a design decision so I will raise the issue with the core team, will report back here when we have discussed.

[m-aciek]

Hi, any updates on that?

It forces us to enable DRF browsable API, otherwise there's an error raised, see https://stackoverflow.com/questions/61961099/wagtail-api-v2-django-template-exceptions-templatedoesnotexist.

It's somewhat contrary to documentation which states

Optionally, you may also want to add rest_framework to INSTALLED_APPS. This would make the API browsable when viewed from a web browser but is not required for basic JSON-formatted output.

https://docs.wagtail.org/en/stable/advanced_topics/api/v2/configuration.html#enable-the-app

[mdfathi99]

This helped me. Here is the simple code in api.py

from rest_framework.renderers import JSONRenderer

...

class ProdPagesAPIViewSet(PagesAPIViewSet):
    renderer_classes = [JSONRenderer]
    name = "pages"

api_router.register_endpoint("pages", ProdPagesAPIViewSet)

[bcdickinson]

I've just hit this issue. I think as @m-aciek says, there's a documentation bug here. No code would need to change in Wagtail if we just documented that you need to subclass the various ViewSet subclasses to set your desired renderer classes, particularly if you want to remove the browsable API renderer.

[zerolab]

I agree with this. Marked the issue as such. PRs welcome ;)

[salty-ivy]

https://docs.wagtail.org/en/stable/advanced_topics/api/v2/configuration.html#
already states that we can subclass these APIViewSet classes

although it, doesn't show how so i would just add a code snippet to show that