RestTemplate Status Code Handling

I was writing a  Spring Boot microservice that called an external service. If the service returned a `500`, the payload of the response had an error code that we wanted to send back to the service that called us. I was using RestTemplate so I thought I could just use:

if (responseEntity.getStatusCode().is2xxSuccessful()){
// happy path
}
if (responseEntity.getStatusCode().is5xxServerError()){
// do the error thing
}

But it’s not that easy. It seems that if the RestTemplate gets anything but a 2xx response, Spring’s default error handler will throw an exception. You won’t even get a chance to do anything with your ResponseEntitybecause the exception happens before that. I even found a recent bug report on the matter. Anyway, I had a chicken and an egg problem – I couldn’t parse the exception out because I didn’t have an entity for it and I didn’t have an entity because the response wasn’t a success. Of course, I may have to accept more status codes than just a 200 or a 500, so I wanted it to be configurable. This old blog entry led me in the right direction of making my own ErrorHandler. What I ended up doing was making an ErrorHandler where I injected the statuses I wanted to make.

I made a simple (and contrived) example on github. It’s actually very simple when you think about it.

My properties file looked like this:

good-status=OK,NOT_ACCEPTABLE

 

I used the words instead of the error codes. You could obviously change it.

The meat is in the MyResponseErrorHandler class. I injected the property is and then simply tested to see if the error existed:

@Component
public class MyResponseErrorHandler implements ResponseErrorHandler {
    private static final Logger log = LoggerFactory.getLogger(MyResponseErrorHandler.class);
 
    private List acceptableStatus;
 
    public  MyResponseErrorHandler(@Value("${good-status}") String goodStatus) {
 
        acceptableStatus = Arrays.stream(goodStatus.split(","))
                .map(HttpStatus::valueOf)
                .collect(Collectors.toList()) ;
 
 
    }
 
    @Override
    public void handleError(ClientHttpResponse response) throws IOException {
        log.error("Response error: {} {}", response.getStatusCode(), response.getStatusText());
    }
 
    @Override
    public boolean hasError(ClientHttpResponse response) throws IOException {
        return !acceptableStatus.contains(response.getStatusCode());
 
    }
}

And then I just inject the error handler in my client class and use it to construct the RestTemplate

 @Autowired
    public MyConsumerService(RestTemplateBuilder restTemplateBuilder,
                             MyResponseErrorHandler myResponseErrorHandler
                             ) {
 
        this.restTemplate = restTemplateBuilder
                   .errorHandler(myResponseErrorHandler)
                   .build();
    }

And that’s it – I didn’t do anything else.

The bug I referenced above said that this will be easier to do with WebClient in Spring 5. Of course, that means Spring Boot 2 (which, as I write this, is finally on RC1). So I hope that this will help others that are working in Spring Boot 1.5 for a while.

About the Author

Object Partners profile.

One thought on “RestTemplate Status Code Handling

  1. Red says:

    Thank you for sharing this good idea

  2. Jason says:

    Thank you for sharing this as well. Was encountering the same issue you were. Like you said, now that you showed the solution it actually is pretty simple but couldn’t figure it out for the life of me.

  3. Rick Osborn says:

    It’s good to bubble these up properly into the logging aggregator/drainpipe.

Leave a Reply

Your email address will not be published.

Related Blog Posts
Building Better Data Visualization Experiences: Part 1 of 2
Through direct experience with data scientists, business analysts, lab technicians, as well as other UX professionals, I have found that we need a better understanding of the people who will be using our data visualization products in order to build them. Creating a product utilizing data with the goal of providing insight is fundamentally different from a typical user-centric web experience, although traditional UX process methods can help.
Kafka Schema Evolution With Java Spring Boot and Protobuf
In this blog I will be demonstrating Kafka schema evolution with Java, Spring Boot and Protobuf.  This app is for tutorial purposes, so there will be instances where a refactor could happen. I tried to […]
Redis Bitmaps: Storing state in small places
Redis is a popular open source in-memory data store that supports all kinds of abstract data structures. In this post and in an accompanying example Java project, I am going to explore two great use […]
Let’s build a WordPress & Kernel updated AMI with Packer
First, let’s start with What is an AMI? An Amazon Machine Image (AMI) is a master image for the creation of virtual servers in an AWS environment. The machine images are like templates that are configured with […]