get_related_resource_type returns parent model name

[martinmaillard]

This is a simplified version of my API:

class Survey(models.Model):
    pass

class Question(models.Model):
    survey = models.ForeignKey(Survey, related_name='questions')

class SurveySerializer(serializers.ModelSerializer):
    class Meta:
        model = Survey
        fields = ('id', 'questions')
        read_only_fields = ('questions',)

class SurveyViewSet(viewsets.ModelViewSet):
     queryset = Survey.objects.all()
     serializer_class = SurveySerializer

Now if I request a survey, the type of the questions is not correct :

>>> GET '/surveys/1'
{
    'data': {
        'id': '1',
        'type': 'surveys',
        'attributes': {},
        'relationships': {
            'questions': {
                'data': [
                    {
                        'id': '1',
                        'type': 'surveys',
                        'attributes': {},
                    },
                ],
            },
        },
    },
}

The issue seems to be in utils.get_related_resource_type. I would submit a PR, but I'm not entirely sure how to fix it without breaking something else...

Also, I'm guessing that it will be necessary to be able to define a resource_name for related models and the relationships handling code will change, but this is still a big issue.

[jsenecal]

Pull latest version from github, I fixed that I think in some commit.

[martinmaillard]

Thanks for the quick reply! I upgraded to the latest commit on "develop" and the problem is still happening...

[jsenecal]

Yes you are right, I couldn't see the whole picture from my cellphone. The get_related_resource_type method is hoping to be intelligent and tries to find the related name from the field name when everything else fails.

We are going to refactor this to be able to define a resouce_name as you suggested.

[jsenecal]

Actually, the more I read it the more I think the behavior is the right one - Model 'survey' is referencing to the same model. so the relation model is in fact survey as well. Unless I misread your code...

Are you sure the output is the proper one? it doesn't make sense to have attributes where you put them under questions

[martinmaillard]

The records in the questions relationship should have the type questions, not surveys.

[jsenecal]

Oups - yes you are right - sry

[mkohram]

#74 should be merged with this.

[jerel]

This should be fixed by 64f8a6b, if it doesn't resolve your issue I'll reopen.

[martinmaillard]

The proper model is now used, but the first letter is a capital, which is probably not intended ?

>>> GET '/surveys/1'
{
    'data': {
        ...
        'relationships': {
            'questions': {
                'data': [
                    {
                        'id': '1',
                        'type': 'Questions',
                        'attributes': {},
                    },
                ],
            },
        },
    },
}

[jsenecal]

@martinmaillard I noticed that behavior as well, I think this was introduced in commit eeab460 altough I would like @schtibe to comment on this as he might have done this on purpose

[schtibe]

@jsenecal Yes and no. Actually, with this commit it would've been underscored (which wouldn't be the correct behaviour as well I guess?) Commit 5b64567 then removed the default underscore behaviour without introducing the lowercase-ing again.
Pull Request #92 wouldn't fix that either, and just return the values as-is. But it's exactly the place to fix it, see my comments there.

[schtibe]

@martinmaillard FYI there is a new option to format these keys: https://github.com/django-json-api/django-rest-framework-json-api/blob/develop/docs/usage.md#relationship-types

[martinmaillard]

That's great ! Thank you !

Now I'm gonna be really annoying: in my actual use case, the questions relationship is polymorphic. Each instance can have a different type subclassing Question (GreatQuestion, SuperQuestion). I think the whole point of specifying the type of each record in json-api is to support this kind of use case. So for ManyRelatedField and ListSerializer, the relation_type should probably be extracted for each instance, instead of once for the whole collection. What do you think ? Do you want me to make a PR so we can discuss on actual code ?

[jerel]

That sounds like a valid use case. I would welcome a PR so we can discuss it further