Adapter mixin causes error when API returns empty object & 204

[simonihmig]

Getting this ember-data error after migrating to fetch and using the adapter mixin: Assertion Failed: normalizeResponse must return a valid JSON API document: One or more of the following keys must be present: "data", "errors", "meta".

This happens when the API returns a 204 response, but with an empty objects as the payload ("{}"). Our real API actually doesn't do this, but Mirage's default handler for DELETE calls seems to return this.

It seems this was caused by #60, which changed the way a 204 response is handled in determineBodyPromise().

jQuery's ajax seems to handle this differently. The raw xhr object has a status of 204 and "{}" as the responseText, but the success hook nevertheless receives undefined as the payload, as can be seen on this screenshot:

To be a drop-in replacement, I think this should behave the same way as before, i.e. return undefined (or maybe { data: null } as it was before)!?

[nlfurniss]

hey @simonihmig!

Seems like something that should be changed in Mirage. According to httpstatus, A 204 response is terminated by the first empty line after the header fields because it cannot contain a message body.

The logic in ember-fetch assumes that a 204 is being implemented this way

[simonihmig]

@nlfurniss hey, yes, I should probably create an issue for mirage as well. But I nevertheless think this could maybe be handled a bit better here as well, i.e. ignore any payload in the adapter mixin for a 204 response. Don't you think?

[tchak]

I just want to mention that we are moving fetch support to Ember Data itself : emberjs/data#5386

[xg-wang]

Hi @simonihmig

To be a drop-in replacement, I think this should behave the same way as before, i.e. return undefined (or maybe { data: null } as it was before)!?

But the PR (it's same as now) you linked, the handling is to return { data: null }

if (response.ok && (status === 204 || status === 205 || requestData.method === 'HEAD')) {
    payload = { data: null };
}

Is it the expected output? Or the payload should be an empty string in 204 case?

[simonihmig]

Closing this, as this has been fixed in Mirage, and the fetch adapter mixin is deprecated anyway.