Globbing should return 200 OK even if empty

[JornWildt]

Assuming I have a container named /notes in my POD and this container contains resources matching /notes/note-* I get a nice list of those resources if I do a GET of /notes/note-*.

But if the /notes container is empty and I try GET /notes/note-* I get 404 - not found.

If think that is wrong, The container is there and any attempt to get a filtered list of its content should return 200 OK since the list is there (the container exists) but it is simply empty as there are no matching resources in the container.

Returning 404 tells the client "You made a mistake - there is nothing here". But the client did not make a mistake - it simply asked for an empty list, not a missing-non-existing list.

[scenaristeur]

if the /notes container is empty and You try GET /notes/note-* , there is nothing in /notes that match note-*, i'm agree with the 404.

[Ryuno-Ki]

What about using a 204 - No Content?

[RubenVerborgh]

200 or 204 are the only right options. 4xx means client error; but there is no client error. Rather, the resource /notes/note-* corresponds to "the aggregation of…" and that resource always exists, regardless of whether it is empty.

200 is easiest for consistency reasons; 204 is equally fine.

[JornWildt]

I like 204. It acknowledges that the query is valid - it just doesn't return anything.

Returning 404 would trigger error handling in the client - potentially yielding a warning message to the end user "Something went wrong - the query engine is not there!" confusing the end user since nothing did indeed go wrong.

If the /notes container does not exist at all, I would find 404 a proper answer.

It is kind of the same discussion for (non networked) code that return a list of items - should it return null if there are no elements or should it return an empty list? I would prefer the empty list.

But it is an old discussion - see for instance https://stackoverflow.com/questions/11746894/what-is-the-proper-rest-response-code-for-a-valid-request-but-an-empty-data

[RubenVerborgh]

But it is an old discussion - see for instance stackoverflow.com/questions/11746894/what-is-the-proper-rest-response-code-for-a-valid-request-but-an-empty-data

That's a different case:

For example you run a GET request for users/9 but there is no user with id #9.

In our case, it's really simple. The resource "the aggregation of…" exists, so no client error. If the parent container does not exist, that's something else.

The reason we can choose between 200 or 204 is that the empty RDF document is also a syntactically valid Turtle document; a zero-byte document would be invalid HTML/XML/JSON-LD. But I like 204 because it is then the same across representations, and doesn't choke any parsers.

[michielbdejong]

Won't fix while we're discussing the proposal to remove globbing from the spec

[RubenVerborgh]

@michielbdejong Catch-22 then, as @melvincarvalho (understandably) is objecting to that change until there is an alternative.