add get_schema_operation_parameters() for Open API 3 generateschema

[n2ygk]

Fixes #1083

Implements Open API 3 (formerly known as Swagger) schema generation by upstream DRF 3.9+ generateschema management command.

[codecov-io]

Codecov Report

Merging #1086 into master will decrease coverage by 0.23%.
The diff coverage is 62.5%.

@@            Coverage Diff            @@
##           master   #1086      +/-   ##
=========================================
- Coverage   98.34%   98.1%   -0.24%     
=========================================
  Files          15      15              
  Lines        1208    1216       +8     
=========================================
+ Hits         1188    1193       +5     
- Misses         20      23       +3

Impacted Files	Coverage Δ
django_filters/rest_framework/backends.py	91.46% <62.5%> (-3.14%)	⬇️

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[carltongibson]

Hi @n2ygk. Super. Thanks for this.

[n2ygk]

@carltongibson If I change it to queryset = view.queryset, the only test that fails is this one, because the get_queryset() override is ignored:

django-filter/tests/rest_framework/test_backends.py

Lines 133 to 151 in 556ce27

	def test_filterset_fields_list_with_bad_get_queryset(self):
	"""
	See:
	* https://github.com/carltongibson/django-filter/issues/551
	"""
	class BadGetQuerySetView(FilterFieldsRootView):
	filterset_fields = ['decimal', 'date']
	def get_queryset(self):
	raise AttributeError("I don't have that")
	backend = DjangoFilterBackend()
	with warnings.catch_warnings(record=True) as w:
	warnings.simplefilter("always")
	fields = backend.get_schema_fields(BadGetQuerySetView())
	self.assertEqual(fields, [], "get_schema_fields should handle AttributeError")

======================================================================
FAIL: test_filterset_fields_list_with_bad_get_queryset (tests.rest_framework.test_backends.GetSchemaFieldsTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/alan/src/django-filter/tests/rest_framework/test_backends.py", line 150, in test_filterset_fields_list_with_bad_get_queryset
    self.assertEqual(fields, [], "get_schema_fields should handle AttributeError")
AssertionError: Lists differ: [Field(name='decimal', required=False, loc[266 chars]one)] != []

First list contains 2 additional elements.
First extra element 0:
Field(name='decimal', required=False, location='query', schema=<coreschema.schemas.Number object at 0x10e10a9b0>, description=None, type=None, example=None)

[carltongibson]

“If I change...”

Why would you do that? 🙂

It’s just not right to access the queryset directly.

(That’s what I don’t follow...)

[n2ygk]

Why would you do that? 🙂

No good reason? Because it's there? Because it's named queryset not _queryset so it must be a "public" member? Because lots of bad examples out there like this: https://stackoverflow.com/questions/19707237/use-get-queryset-method-or-set-queryset-variable

[carltongibson]

I guess see rest_framework.generics.

tl;dr: Client code should always call get_queryset().

[n2ygk]

I guess see rest_framework.generics.

tl;dr: Client code should always call get_queryset().

Yep, learn something new every day. Sometimes for the second or third time. :-)

[n2ygk]

@carltongibson just pinging to see if you are OK with merging this?

[carltongibson]

Super. Thanks.