Error - Returning JSON along with HTTP status code error JAX-RS

Question

@POST
@Consumes({MediaType.APPLICATION_JSON})
@Produces({MediaType.APPLICATION_JSON})
@Path("/data/services")
public Response  DiscoverDevice(BlockDevsPost blockdevice) {

    for (DeviceIdentifier device : blockdevice.getDevice()) {
        String dev = device.Device();
        System.out.println("DEVICE "+ dev);
        if (dev == null || dev.equals("")){
            return Response.status(Response.Status.BAD_REQUEST).entity("Device cannot be null or empty.").build();
        }
    }
}

Getting this error when fired POST from REST Client when dev is null. I am not able to get JSON and this error is thrown:

Unexpected character (D) at position 0. Device Identifier cannot be null or empty.

Where D in Device Identifier marked as Red which means it is not returning JSON as response.

I am not able to get JSON an this error is thrown when dev is null — VIP
– VIP, Commented Feb 17, 2017 at 10:34
When dev is sent as null from REST Client . It will throw the error as HTTP Bad Request error . But the response message I am getting - Unexpected character (D) at position 0. Device Identifier cannot be null or empty. where D in Device Identifier marked as Red which means it is not returning JSON as response. — VIP
– VIP, Commented Feb 18, 2017 at 3:09

pedrofb · Accepted Answer · 2017-02-21 11:41:04Z

1

Your client is expecting to get JSON but you have set a plain string in the Response entity and application/json as content-type. You need to return a valid JSON. For example

return Response
           .status(Response.Status.BAD_REQUEST)
           .entity("{\"error\":\"Device cannot be null or empty.\"}")
           .build();

You can also build the json response string using your preferred mapper (you will need to add a dependency). This is an example using Jackson

Jackson using API

ObjectMapper mapper  = new ObjectMapper();
ObjectNode objectNode = mapper.createObjectNode();
objectNode.put("error", "Device cannot be null or empty.");
String json = mapper.writeValueAsString(objectNode);

Jackson using POJO

class ErrorBean{
   private String error;
   //getters and setters
}

ObjectMapper mapper = new ObjectMapper();
ErrorBeanerrorBean = new ErrorBean();
errorBean.setError ("Device cannot be null or empty.");
String json = mapper.writeValueAsString(errorBean);

You can also return POJO from your service method and let the JAX-RS implementation to convert them to JSON (this means change the response type). See https://www.mkyong.com/webservices/jax-rs/json-example-with-jersey-jackson/

edited Feb 21, 2017 at 11:41

answered Feb 18, 2017 at 9:16

pedrofb

39.7k7 gold badges104 silver badges156 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

VIP Over a year ago

Worked !. Thank-you.

VIP Over a year ago

Escape of double quotes doesnt look proper. Is there any other way to write the wrapper to accept the JSON Object.

pedrofb Over a year ago

You can build the JSON string using a mapper library: Jackson, Gson, jettison... See an example in the updated answer.

Collectives™ on Stack Overflow

Error - Returning JSON along with HTTP status code error JAX-RS

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related