Document how to use rest_framework.filters.SearchFilter

[n2ygk]

Fixes #432

Description of the Change

Documents how to use rest_framework.filters.SearchFilter along with the other filter backends.

Includes updates to the example app to demonstrate usage and test cases.

CHANGELOG.md remains unchanged because this is included in: "Add optional jsonapi-style filter backends"

I also documented some filterset_fields to complement the search_fields in the usage document showing how to configure filter backends.

Checklist

• PR only contains one change (considered splitting up PR)
• unit-test added
• documentation updated
• changelog entry added to CHANGELOG.md
• author name in AUTHORS

[sliverc]

This test is a bit difficult to comprehend. It would be much easier to write it with pytest parametrize.

I ask myself though do we really need a test for SearchFilter? It is DRF functionality and as such it is already tested in DRF itself and we just do same work again. Hence I think we could remove this test.

[n2ygk]

@sliverc My reason for the test is because it is testing (demonstrating) the example app’s usage. The tests after all are in `example/tests`. w.r.t to pytest parameterize, I'm not sure this would be any more clear. Let me take a crack at better documenting the test, which was written to be somewhat independent of the fixture content, in case someone changes it, but of course still dependent on my given lest of test keywords being present. If after the next commit you still think it should be removed, we can do that.

[sliverc]

@n2ygk if this is the case then the test should be simplified where only one keyword is searched for and a simple assert result.json() == expected will do. This will show how it works and is readable by someone who wants to see how search filter is used.

[n2ygk]

@sliverc Sorry, I didn't notice your followup comment until just now... Please take a look at the test case again before we kill it:-(. I am also happy to add the result.json() assertion with static test values but still think it's valuable to demonstrate the multi-keyword searching across ORM-related fields.

[sliverc]

OK. Let's leave it this way and merge. Thanks.