Getting JSON from RetrofitError object using Retrofit

Question

I am using the Retrofit library to do REST calls to a service I am using.

If I make an API call to my service and have a failure, the service returns a bit of JSON

Answer 1

So after a little more hunting I found the answer.

Here's my failure callback:

@Override public void failure(RetrofitError retrofitError) {
    String serverError = null;
    try {
        serverError = extractServerError(retrofitError.getResponse().getBody().in());
    } catch (Exception e) {
        Log.e("LOG_TAG", "Error converting RetrofitError server JSON", e);
    }

    if (serverError!=null) {
        Log.i(LOG_TAG, serverError);
    }

    Intent intent = new Intent(ACTION_REGISTRATION_ERROR);
    intent.putExtra("ServerError", serverError);
    LocalBroadcastManager.getInstance(FamDooApplication.CONTEXT).sendBroadcastSync(intent);
}

And here's the method that is called to extract the server error:

public static String extractServerError(java.io.InputStream is) {
    String serverError = null;
    String serverErrorDescription = null;
try {

    String s = convertStreamToString(is);

    JSONObject messageObject = new JSONObject(s);
    serverError = messageObject.optString("error");
    serverErrorDescription = messageObject.optString("error_description");
    if (serverErrorDescription!=null && !serverErrorDescription.equals("")) {
        return serverErrorDescription;
    } else {
        return serverError;
    }
    //String serverStack = messageObject.getString("stack");
} catch (Exception e) {
    Log.e("Basemodel", "Error converting RetrofitError server JSON", e);
}

return "";
}

This will extract the error information sent by the service that is encoded in the JSON.

Answer 2

I compile many answer and wrote some code to achieve something nicer :

{
    "errors": {
        "email": [
            "Email not valid.",
            "Unable to find the user toto@toto.fr."
        ]
    }
}

I take all item in 'email' and display them concatained with Guava Joiner:

String json =  new String(((TypedByteArray)error.getResponse()
    .getBody()).getBytes());

Map<String, Object> map = new Gson().fromJson(
    json, new TypeToken<Map<String, Map<String, List<String>>>>() {}.getType());

try {
    List<String> errorsEmail = 
        (List<String>) ((Map)map.get("errors")).get("email");
    Toast.makeText(getApplicationContext(), Joiner.on("\n")
        .join(errorsEmail), Toast.LENGTH_SHORT).show();
} catch(Exception e){
    Log.e(Constants.TAG, e.getMessage());
}

Answer 3

A much neater way to do this is to create a class that can do the parsing/conversion for you, one that you can call anytime, anywhere.

public class ApiError {
    public String error = "An error occurred";

    public ApiError(Throwable error) {
        if (error instanceof HttpException) {
            String errorJsonString = null;
            try {
                errorJsonString = ((HttpException) 
                error).response().errorBody().string();
            } catch (IOException e) {
                e.printStackTrace();
            }
            JsonElement parsedString = new 
            JsonParser().parse(errorJsonString);
            this.error = parsedString.getAsJsonObject()
                                     .get("error")
                                     .getAsString();
        } else {
            this.error = error.getMessage() != null ? error.getMessage() : this.error;
        }
    }
}

You can now use this anywhere, like so

ApiError error = new ApiError(error)
error.error

This is all from this blog post (which I wrote).