Ability to declare a container as both @language and @set

[danmichaelo]

Related to #269 . I would like to use @language maps with @set, but haven't found a way to do so.

My data is following the SKOS model, where each concept can have one preferred label per language, and any number of alternative labels per language. To make the data easy to work with, I'm trying to achieve the following output:

{
  "@id": "http://data.ub.uio.no/realfagstermer/c012548",
  "prefLabel": {
    "nb": "Abbor",
    "en": "European perch"
  },
  "altLabel": {
    "nb": [
      "Åbor"
   ]
  }
}

The best context I've come up with is this (JSON-LD Playground):

{
  "@context": {
    "skos": "http://www.w3.org/2004/02/skos/core#",
    "prefLabel": {
      "@id": "skos:prefLabel",
      "@container": "@language"
    },
    "altLabel": {
      "@id": "skos:altLabel",
      "@container": "@language"
    }
  }
}

but this makes altLabel a set (or a js list) only if there's more than one item, an object otherwise. I would like to force altLabel to always be a set.

[lanthaler]

I don’t know how frequent having multiple string values per language are (I haven’t seen this often) but I tagged it as a request for the next version of JSON-LD. Thanks for the suggestion

[akuckartz]

The current behavior is the one I would expect. But non-RDF developers might like sets (JS arrays) with a single element. That could be a more general use case.

[danmichaelo]

@akuckartz Yeah, as a JS developer I find that I easily end up with a lot of extra code to normalize the data to make it easier work with. For instance I currently have something like this to cast the altLabels to arrays:

function asArray(x) {
  return typeof(x) == 'undefined' ? [] : (typeof(x) == 'string' ? [x] : x);
}
function valuesAsArray(x) {
  x = x ? x : {};
  Object.keys(x).forEach(function(key) {
    x[key] = asArray(x[key]);
  });
  return x;
}
concept.altLabel = valuesAsArray(concept.altLabel);

[dlongley]

@danmichaelo, btw, if you're using jsonld.js you can use:

var thisIsAnArrayOfValues = jsonld.getValues(node, 'property');

[danmichaelo]

@dlongley Sweet, thanks!

[azaroth42]

We have this use case as well, for serializing vocabularies in SKOS and in providing data level internationalization. Each term has multiple labels in multiple languages, and it would be nice to be able to use @set to ensure that the resulting structure is consistent, even if there is a single element in the list.