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smart-on-fhir / client-js

JavaScript client for FHIR
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HttpError and humanizeError destroy machine-processable error responses (OperationOutcome) #100

Closed lawley closed 4 years ago

lawley commented 4 years ago

While FHIR defines a OperationOutcome as a universal and reasonably useful machine-readable/processable result for errors, this library obfuscates it with the humanizeError function and the HttpError interface.

It would be very useful to expose a JSON error response through the HttpError interface.

vlad-ignatov commented 4 years ago

That is an interesting idea. The reason for the current behavior is that even though an OperationOutcome is a good idea in a REST API, we are dealing with a Promise interface. When a promise is rejected, it has to be done with an Error object.

However, what you are proposing makes sense. You are the first one to be interested in OperationOutcome on the client side. I guess I can make it so that the OperationOutcome object is attached to the error as an additional property, so that you can do:

client.request("Patient").catch(error => console.log(error.operationOutcome));

// or
try {
    await client.request("Patient");
} catch (httpError) {
    console.log(httpError.operationOutcome)
}

Is that what you were talking about?

lawley commented 4 years ago

Yes, exactly. In order to provide useful feedback to the user in my clients, access to the OperationOutcome like this is just what I need.

vlad-ignatov commented 4 years ago

Great! This will be included in the next release, and if you use it as library (via script tag) you can give it a try now using the latest dev build from https://combinatronics.com/smart-on-fhir/client-js/master/dist/build/fhir-client.js.

The HttpError is actually used in different situations and not only for the requests that the Client is making. For that reason, the new property of the error is called body and can be an OperationOutcome, a JSON object, a string or null, depending on the server response. In your case, I think you can assume that what you get is an OperationOutcome but if you use TypeScript, you might want to cast the body property to fhirclient.FHIR.Resource or fhirclient.JsonObject first.

vlad-ignatov commented 4 years ago

This is now included in the latest official release - 2.3.10. Thank you!