empty array in query param when using @Separator

[florinspatar]

I have the following examples:

@GET
@Path("/v1/dummy/array1/")
public long[] test1(@QueryParam("id") long[] id) {
    return id;
}

@GET
@Path("/v1/dummy/array2/")
public long[] test2(@QueryParam("id") @Separator(",") long[] id) {
    return id;
}

To send in an empty array, the request URLs look like this:

• https:///rest/v1/dummy/array1
• https:///rest/v1/dummy/array2?id=,

In the second example, if I don't send any id, id will be null instead of empty array. This behavior seems weird. Shouldn't it evaluate to empty array instead of null?

I'm using Wildfly 37.

[jamezp]

I'm seeing a different behavior. With an empty ?id= I get a 404, likely a different issue. However, if I do pass ?id=. I get an empty array. I tested on a String[] array too and got the same results, empty arrays.

The only difference I had was String return types.

@Path("arrays")
public class ArrayResource {

    @GET
    @Path("/long/no-sep")
    public String longArrayNoSep(@QueryParam("id") final long[] values) {
        return "values: " + (values == null ? "null" : Arrays.toString(values));
    }

    @GET
    @Path("/long/sep")
    public String longArraySep(@QueryParam("id") @Separator(",") final long[] values) {
        return "values: " + (values == null ? "null" : Arrays.toString(values));
    }

    @GET
    @Path("/string/no-sep")
    public String stringArrayNoSep(@QueryParam("id") final String[] values) {
        return "values: " + (values == null ? "null" : Arrays.toString(values));
    }

    @GET
    @Path("/string/sep")
    public String stringArraySep(@QueryParam("id") @Separator(",") final String[] values) {
        return "values: " + (values == null ? "null" : Arrays.toString(values));
    }
}

Where I do see a difference is if I leave off the id query parameter, without the @Separator I do see an empty array, with the @Separator annotation I do see a null parameter. That different behavior does seem wrong, but it seems to have been like that for a long time so I'd be a bit hesitant to change the default behavior.

I'm definitely open to other opinions though and let me know if I'm testing something wrong :)

[florinspatar]

You mean if you pass ?id=, not ?id=. you get empty array, right?
One possible workaround would be to also add @DefaultValue(",") if we use @Separator(",")

@GET
@Path("/string/sep")
public String stringArraySep(@QueryParam("id") @Separator(",") @DefaultValue(",") final String[] values) {
    return "values: " + (values == null ? "null" : Arrays.toString(values));
}