Jan 25, 2022

Retrofit2: Get the body from an error response

Retrofit2 is a nice library for making HTTP rest requests. It includes a static utility (CallUtils) for getting the result from your request, but if the api you’re calling doesn’t return a 2xx request it will throw an HttpException. Here is an example of using that CallUtils method.

Call<SomekindOfObject> call = .....;
return CallUtils.getResult(call);

The problem is when there is an error that HttpException does not return the message body, and oftentimes that body has information about why your request failed. To fix this problem I created a static method that captures the body and response code to return the body as part of the exception.

  public static <T> T getResult(retrofit2.Call<T> call) throws MyCustomException {
    if (call != null) {
      try {
        Response<T> response = call.execute();
        if (response.isSuccessful()) {
          return response.body();
        } else {
          String errorMessage = response.errorBody() != null ? response.errorBody().string() : "";
          throw new MyCustomException(response.code(), errorMessage);
        }
      } catch (IOException ioe) {
        throw new MyCustomException(400, "error executing call");
      }
    }
 
    return null;
  }

About the Author

Scott Bock profile.

Scott Bock

Principal Technologist

Scott is a Senior Software Engineer with over 12 years of experience using Java, and 5 years experience in technical leadership positions. His strengths include troubleshooting and problem solving abilities, excellent repertoire with customers and management, and verbal and written communication. He develops code across the entire technology stack including database, application, and user interface.

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