Avoid overwriting of pointer when using custom errors

[brettdh]

The code that produces JSON:API error objects assumes that all fields being validated are under /data/attributes:

django-rest-framework-json-api/rest_framework_json_api/utils.py

Line 339 in b0257c0

def format_drf_errors(response, context, exc):

and there doesn't appear to be a way to override the pointer value when specifying the field on a serializer.

Use case: I would like to be able to specify a serializer for the top-level "meta" field and have any validation errors on that data generate responses properly populated with "source": {"pointer": "/meta/foo"}.

[brettdh]

More generally: I would like to be able to override the pointer that DRFJA creates with a custom value per field. I would guess (but have not tested) that the code linked above also doesn't handle specifying indices for individual errors when data is a list.

[sliverc]

It is currently not possible to have custom error format. It might be handy though also to add other information allowed by json api. Maybe needs to be solved with a custom json api ValidationException but would need to investigate how this can be done properly.

What you could always do is to return your own Response with the error in the format you need it.

[sliverc]

While discussing #776 it occurred to me that it actually is already possible to define custom error objects - see test code snippet.

Closing this issue therefore. Please comment in case this doesn't solve this issue.

[Elawphant]

serializers.ValidationError does not support custom source: { pointer: ... }. E.g.

raise serializers.ValidationError([{
        "detail": "This field is required.",
        "source": {
        "pointer": "/data/something"
     }
}])

results in

{
    "errors": [
        {
            "detail": "This field is required.",
            "source": {
                "pointer": "/data"
            }
        }
    ]
}

This issue needs to be reopen.

[sliverc]

Thanks @Elawphant for pointing this out. I have done some research. Indeed, there seems to be an issue but not with custom errors in general but just that the pointer gets overwritten. I think the error is here. Assigning the pointer should only happen if there is no previous pointer. A PR is welcome.