Primary key optimization doesn't work (null attribtue values) with nested includes #708
Description
I ran into this issue when upgrading to a newer version of django-rest-framework-json-api and it seems like a bug to me, unless there is now a different way that this is meant to be accomplished that I'm not seeing in the documentation. The problem is when providing an include parameter for nested children of a resource (for example, ?include=articles.author), those "grandchild" objects are present in the included but they have no attributes.
I was able to recreate this with a simple setup:
Models
class Page(models.Model):
pass
class Author(models.Model):
first_name = models.TextField()
last_name = models.TextField()
class Article(models.Model):
page = models.ForeignKey(Page, related_name='articles', on_delete=models.CASCADE)
author = models.ForeignKey(Author, related_name='articles', on_delete=models.CASCADE)
title = models.TextField()
Serializers
class AuthorSerializer(serializers.ModelSerializer):
class Meta:
model = Author
fields = ('id', 'first_name', 'last_name')
class ArticleSerializer(serializers.ModelSerializer):
author = AuthorSerializer(many=False, read_only=True)
included_serializers = {
'author': AuthorSerializer,
}
class Meta:
model = Article
fields = ('id', 'title', 'author')
class PageSerializer(serializers.ModelSerializer):
articles = ArticleSerializer(many=True, read_only=True)
included_serializers = {
'articles': ArticleSerializer,
}
class Meta:
model = Page
fields = ('id', 'articles')
The view is just a simple ModelViewSet.
class PageViewSet(ModelViewSet):
queryset = Page.objects.all()
serializer_class = PageSerializer
The output of a query /page/?include=articles.author is this:
{
"data": [
{
"type": "Page",
"id": "1",
"attributes": {},
"relationships": {
"articles": {
"data": [
{
"type": "Article",
"id": "1"
}
]
}
}
}
],
"included": [
{
"type": "Article",
"id": "1",
"attributes": {
"title": "Some Article"
},
"relationships": {
"author": {
"data": {
"type": "Author",
"id": "1"
}
}
}
},
{
"type": "Author",
"id": "1",
"attributes": {
"first_name": null,
"last_name": null
}
}
]
}
The first_name and last_name fields for the included Author are present but have null values, when data exists in the database for this object. This issue seems to have been introduced in django-rest-framework-json-api v2.6.0, as the fields are returned correctly when using 2.5.0.