REST service: The proper way of returning exception

Question

I use Jersey API for my REST service. My question is: Is there a more elegant way of returning exceptions in a JSON form? Is it better to concern myself with creating a json obj

Answer 1

You can create a class like the one below to represent an error,

@JsonPropertyOrder({ "code", "field", "message" })
public class ErrorInfo {

    private String code;

    private String field;

    private String message;

    public String getCode() {
        return code;
    }

    public void setCode(String code) {
        this.code = code;
    }

    public String getField() {
        return field;
    }

    public void setField(String field) {
        this.field = field;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

}

You can create a class which extends an exception like this,

public class InvalidInputException extends RuntimeException {

    private static final long serialVersionUID = -5027121014723838738L;

    private List errors;

    public List getErrors() {
        return this.errors;
    }

    public InvalidInputException(List errors) {
        super();
        this.errors = errors;
    }

    public InvalidInputException(String message, List errors) {
        super(message);
        this.errors = errors;
    }

}

And have a exception mapper, where you can convert the List to json and return to the user with http status code 400 (Bad Request).

@Provider
public class InvalidInputExceptionMapper implements ExceptionMapper {

    @Override
    @Produces(MediaType.APPLICATION_JSON)
    public Response toResponse(InvalidInputException e) {

        ResponseBuilder rb = Response.status(Status.BAD_REQUEST);

        rb.entity(e.getErrors());
        return rb.build();   
    }
}

Http Response will be,

HTTP/1.1 400 BAD REQUEST
{
"errors": [{
    "error": {
        "code": "100",
        "field": null,
        "message": "Name is required"
    },
    "error": {
        "code": "100",
        "field": null,
        "message": "Age is required"
    }
}]

}