Use REST framework serializer functionality to extract includes

[Anton-Shutik]

Fixes #

Let's say we have code like below:

class ParentSerializer(HyperlinkedModelSerializer):
    child = json_api_relations.ResourceRelatedField(
        related_link_view_name='parent-child',
        related_link_url_kwarg='parent_pk',
        self_link_view_name='parent-relationships',
        read_only=True,
        source='intermidiate_object.child',
        model=Child
    )

Url GET api/parent/1/ works fine until I want to "include" child in the response (GET api/parent/1/?include=child). It does not add the included section, because renderer fails to calculate child property in extract_relation_instance method.
Child is not just Foreign key, it is a property of intermidiate_object that we have on the parent. I'm pretty sure we have to calculate it exactly same way we do when serializing parent serializer.

Checklist

• PR only contains one change (considered splitting up PR)
• unit-test added
• documentation updated
• CHANGELOG.md updated (only for user relevant changes)
• author name in AUTHORS

[sliverc]

I like where this PR is going. This change might not be 100% backwards compatible especially the serializer_method part. However a change like suggested in #639 could solve this.

[sliverc]

😄 just looked at the SerializerMethodResourceRelatedField implementation which actually overwrites get_attribute, so your change should work. If you could add a test and changelog that would be great.

Hint: currently failing tests should be fixed with #634

[codecov]

Codecov Report

Merging #632 into master will decrease coverage by 0.82%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #632      +/-   ##
==========================================
- Coverage   96.16%   95.34%   -0.83%     
==========================================
  Files          56       56              
  Lines        2866     2855      -11     
==========================================
- Hits         2756     2722      -34     
- Misses        110      133      +23

Impacted Files	Coverage Δ
rest_framework_json_api/renderers.py	86.79% <100%> (-0.58%)	⬇️
rest_framework_json_api/compat.py	50% <0%> (-50%)	⬇️
rest_framework_json_api/metadata.py	25% <0%> (-23.34%)	⬇️
rest_framework_json_api/django_filters/backends.py	86.66% <0%> (-13.34%)	⬇️
example/tests/test_views.py	100% <0%> (ø)	⬆️

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[codecov]

Codecov Report

Merging #632 into master will decrease coverage by 0.03%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #632      +/-   ##
==========================================
- Coverage   96.16%   96.13%   -0.04%     
==========================================
  Files          56       56              
  Lines        2870     2869       -1     
==========================================
- Hits         2760     2758       -2     
- Misses        110      111       +1

Impacted Files	Coverage Δ
example/tests/unit/test_renderers.py	100% <100%> (ø)	⬆️
rest_framework_json_api/renderers.py	86.79% <100%> (-0.58%)	⬇️

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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[Anton-Shutik]

@sliverc Done

[Anton-Shutik]

@sliverc Are there any more updates required ?

[sliverc]

Test looks good. See inline comment for a small change.

[sliverc]

Merged. Thanks for your work.

[Anton-Shutik]

Cool, thanks. Any expected release date ?