Minimal scoped context affects term selection with index container

[gkellogg]

From https://github.com/w3c/wot-thing-description/issues/894

Compacting the following:

{
  "https://www.w3.org/2019/wot/td#hasPropertyAffordance": [
    {
      "http://purl.org/dc/terms/title": "Switch"
    }
  ],
  "http://purl.org/dc/terms/title": "46203"
}

with the following context:

{
  "@context": {
    "td": "https://www.w3.org/2019/wot/td#",
    "dct": "http://purl.org/dc/terms/",
    "properties": {
      "@id": "td:hasPropertyAffordance",
      "@type": "@id",
      "@container": "@index",
      "@context": {}
    },
    "title": "dct:title"
  }
}

prevents "title" from being used in the output:

{
  "@context": {
    "td": "https://www.w3.org/2019/wot/td#",
    "dct": "http://purl.org/dc/terms/",
    "properties": {
      "@id": "td:hasPropertyAffordance",
      "@type": "@id",
      "@container": "@index",
      "@context": {}
    },
    "title": "dct:title"
  },
  "title": "46203",
  "properties": {
    "@none": {
      "dct:title": "Switch"
    }
  }
}

Instead, it uses "dct:title". Removing "@context": {} from the context makes it work and use "title" instead.

[gkellogg]

See https://github.com/w3c/wot-thing-description/issues/894 and playground.

[davidlehn]

Tests over here: https://github.com/w3c/json-ld-api/pull/490 It's failing at some low level with new basic tests. Haven't debugged yet, but looks like scoped contexts are just overwriting top level contexts?

[davidlehn]

Bisect for basic additive scoped context fails here:

• https://github.com/digitalbazaar/jsonld.js/commit/84b77681d3666cf804e581574f406280ce7bd88b

[davidlehn]

In the code that does processing just to validate, I think the bug can be fixed with activeCtx: rval.clone() instead of just rval. That seems an unfortunate efficiency issue. Is the passed activeCtx supposed to be mutated?

[gkellogg]

There was code to freeze these contests, but it was too expensive too. Might be worth doing it to see where it’s being modified and only duo when necessary.

[RoboPhred]

Given the lack of activity in this issue, I implemented the fix mentioned above and tested it with the updated test suite.

Fix in MR #411

[davidlehn]

The proposed patch was added to jsonld.js 3.2.0 and is live on playground now. I think this issue is fixed. Please test. There is the possibility of a performance regression due to this, but another issue was opened to handle that case.