I find it amazing that "DRY" has become such a positive pattern when it was touted as one of the driving points of the Ruby on Rails framework. Don't repeat yourself.
For instance, Java folks are always ready to throw exceptions instead of letting stuff resolve itself if it doesn't quite work.
If I returned a fake value - the client would get a 200 response on his attempt to delete a non-existent resource, which is clearly the incorrect behavior. I could return nothing - but then the client would see a 204. So, I choose to throw an exception with a response 'NOT_FOUND'
throw new WebApplicationException(Response.Status.NOT_FOUND);
There are a few things I'd like to point out to add to this example:
1) JAX-RS is still new. In the future, they might improve the exception handling or whatnot (so if you return null, they might decided to return 404 ... who knows)
2) We can always wrap all JAX-RS with a Filter. So you can throw JPA level exception (not found) and let the filter catch it and convert it to WebApplicationException(404). Thus in theory, your JAX-RS implementation won't have any RuntimeException explicitly in the code.
@DELETE
@Path("{uid: [0-9]+}")
public Response deleteStudent(@PathParam("uid") int uid) {
final Student deletedStudent = STUDENTS.remove(uid);
if (deletedStudent == null) {
return Response.status(Response.Status.NOT_FOUND).build();
} else {
return Response.ok().entity(true).build();
}
}The full (buildable) source code - including the CsvParam and DateParam classes - are here: https://github.com/smanek/students