Modified and created dates are serialized as literals

[dannylamb]

When serializing an entity as jsonld, the modified and created dates are being written as literals with the sites default language. They should be serialized as instances of http://www.w3.org/2001/XMLSchema#dateTime instead.

To reproduce:

• Create a new collection
• Retrieve its jsonld representation. This can be done by appending ?_format=jsonld to the end of its URL and visiting/cURLing it. If cURLing, you'll need to provide an authentication token. If you're visiting it in the browser, you will have to enable cookie authentication through the restui interface at /admin/config/services/rest
• You should see something like this:

{
    "@graph":[
        {
            "@id":"http:\/\/localhost:8000\/node\/1?_format=jsonld",
            "@type":[
                "http:\/\/pcdm.org\/models#Collection",
                "http:\/\/schema.org\/CollectionPage"
            ],
            "http:\/\/purl.org\/dc\/terms\/title":[
                {
                    "@value":"A Collection",
                    "@language":"en"
                }
            ],
            "http:\/\/schema.org\/author":[
                {
                    "@id":"http:\/\/localhost:8000\/user\/1?_format=jsonld"
                }
            ],
            "http:\/\/schema.org\/dateCreated":[
                {
                    "@value":"2017-06-13T13:14:55+00:00",
                    "@language":"en"
                }
            ],
            "http:\/\/schema.org\/dateModified":[
                {
                    "@value":"2017-06-13T13:15:04+00:00",
                    "@language":"en"
                }
            ],
            "http:\/\/purl.org\/dc\/terms\/description":[
                {
                    "@value":"Holds stuff",
                    "@language":"en"
                }
            ]
        },
        {
            "@id":"http:\/\/localhost:8000\/user\/1?_format=jsonld",
            "@type":[
                "http:\/\/schema.org\/Person"
            ]
        }
    ]
}

If you do a lookup in Gemini and track down the resource in Fedora, it'll be a little more obvious it's not a date when compared to the Fedora created and modified dates:

• curl -H "Authorization: Bearer islandora" http://localhost:8000/gemini/drupal/node/1
  Returned d9/51/33/3b/d951333b-8b7e-429c-92ee-d161af59e401. So you can look in up in Fedora with
• curl -H "Authorization: Bearer islandora" http://localhost:8081/fcrepo/rest/d9/51/33/3b/d951333b-8b7e-429c-92ee-d161af59e401`

<http://localhost:8080/fcrepo/rest/d9/51/33/3b/d951333b-8b7e-429c-92ee-d161af59e401>
        rdf:type               pcdm:Collection ;
        rdf:type               fedora:Container ;
        rdf:type               schema:CollectionPage ;
        rdf:type               fedora:Resource ;
        fedora:lastModifiedBy  "bypassAdmin"^^<http://www.w3.org/2001/XMLSchema#string> ;
        schema:dateModified    "2017-06-13T13:15:04+00:00"@en ;
        schema:author          <http://localhost:8000/user/1?_format=jsonld> ;
        schema:dateCreated     "2017-06-13T13:14:55+00:00"@en ;
        fedora:createdBy       "bypassAdmin"^^<http://www.w3.org/2001/XMLSchema#string> ;
        fedora:lastModified    "2017-06-13T13:15:09.541Z"^^<http://www.w3.org/2001/XMLSchema#dateTime> ;
        fedora:created         "2017-06-13T13:15:09.541Z"^^<http://www.w3.org/2001/XMLSchema#dateTime> ;
        dcterms:description    "Holds stuff"@en ;
        dcterms:title          "A Collection"@en ;
        rdf:type               ldp:RDFSource ;
        rdf:type               ldp:Container ;
        fedora:writable        "true"^^<http://www.w3.org/2001/XMLSchema#boolean> ;
        fedora:hasParent       <http://localhost:8080/fcrepo/rest/> .

The scope of this ticket is to modify the https://github.com/Islandora-CLAW/jsonld module to properly serialize dates. It can be tested by performing the same steps as above, and the date should not be given a language and it should appear as a http://www.w3.org/2001/XMLSchema#dateTime in Fedora.

[kimpham54]

hi @dannylamb, If I wanted to test this ticket/work on it is the issue happening on the 8.x-1.x branch or is it on the commit that the CLAW repo uses, https://github.com/Islandora-CLAW/jsonld/tree/eeec5aada39480615aa328eff2b0d5390dd75309? Which branch should I work off of?

[whikloj]

@kimpham54 you should work off of 8.x-1.x. But so you are aware @ajs6f was looking at this too and I thought that @DiegoPino had done some work on this. So he may have a simple solution up his sleeve.

[dannylamb]

@kimpham54 Eventually, the commit hashes that the CLAW repo uses will be for releases. So if you wanted to work off a commit tied to particular release version, that'd be the way to go. But mainline development should go off of the 8.x-1.x branch as @whikloj suggested.

FWIW we're not keeping up on updating the CLAW repo very well. Ideally it'd be some sort of automated process, but for now, I wouldn't trust them.

[ajs6f]

Yes, @DiegoPino definitely has some ideas here and should be pinged before work goes forward.

[kimpham54]

Thanks all for the information. I'll still try to take a look out of interest

[whikloj]

For the reference of whomever might take this on. I noted that if you alter the rdf mapping you can add a datatype: property which is added to the field in the JSON-LD as @type.

See Islandora IRC logs 2017-06-15 starting at 09:52

[DiegoPino]

@whikloj @ajs6f wonder about the @en part now. Also, i will fix some data types in absence of explicit typing as i did here: https://github.com/Islandora-CLAW/jsonld/blob/8.x-1.x/src/ContextGenerator/JsonldContextGenerator.php#L321-L422 Will have a pull for tomorrow.

[DiegoPino]

@whikloj @ajs6f since i'm here and have a fix in hand, wonder if there are other miss typed properties you have seen around before making the pull request?

[whikloj]

@DiegoPino just wondering if you are still in here. I was doing some digging around and using the getFieldsRdf inside FieldItemNormalizer (right after this }) I was able to change this:

[
  {
    "@id": "http://localhost:8000/node/1?_format=jsonld",
    "@type": [
      "http://pcdm.org/models#Object",
      "http://schema.org/ImageObject"
    ],
    "http://pcdm.org/models#hasFile": [
      {
        "@id": "http://localhost:8000/media/1?_format=jsonld"
      }
    ],
    "http://purl.org/dc/terms/description": [
      {
        "@language": "en",
        "@value": "This is some content"
      }
    ],
    "http://purl.org/dc/terms/title": [
      {
        "@language": "en",
        "@value": "Test Image"
      }
    ],
    "http://schema.org/author": [
      {
        "@id": "http://localhost:8000/user/1?_format=jsonld"
      }
    ],
    "http://schema.org/dateCreated": [
      {
        "@language": "en",
        "@value": "2017-07-12T13:43:27+00:00"
      }
    ],
    "http://schema.org/dateModified": [
      {
        "@language": "en",
        "@value": "2017-07-12T13:44:16+00:00"
      }
    ]
  },
  {
    "@id": "http://localhost:8000/user/1?_format=jsonld",
    "@type": [
      "http://schema.org/Person"
    ]
  },
  {
    "@id": "http://localhost:8000/media/1?_format=jsonld",
    "@type": [
      "http://pcdm.org/use#ServiceFile"
    ]
  }
]

to this

[
  {
    "@id": "http://localhost:8000/node/1?_format=jsonld",
    "@type": [
      "http://pcdm.org/models#Object",
      "http://schema.org/ImageObject"
    ],
    "http://pcdm.org/models#hasFile": [
      {
        "@id": "http://localhost:8000/media/1?_format=jsonld"
      }
    ],
    "http://purl.org/dc/terms/description": [
      {
        "@type": "xsd:string",
        "@value": "This is some content"
      }
    ],
    "http://purl.org/dc/terms/title": [
      {
        "@type": "xsd:string",
        "@value": "Test Image"
      }
    ],
    "http://schema.org/author": [
      {
        "@id": "http://localhost:8000/user/1?_format=jsonld"
      }
    ],
    "http://schema.org/dateCreated": [
      {
        "@type": "xsd:dateTime",
        "@value": "2017-07-12T13:43:27+00:00"
      }
    ],
    "http://schema.org/dateModified": [
      {
        "@type": "xsd:dateTime",
        "@value": "2017-07-12T13:44:16+00:00"
      }
    ]
  },
  {
    "@id": "http://localhost:8000/user/1?_format=jsonld",
    "@type": [
      "http://schema.org/Person"
    ]
  },
  {
    "@id": "http://localhost:8000/media/1?_format=jsonld",
    "@type": [
      "http://pcdm.org/use#ServiceFile"
    ]
  }
]

I had to stop adding the @language property if there was an @type one, apparently JSON-LD doesn't like that.

Still need to expand the namespaces, but I wanted to see how you were doing. If you're close then I'll move on, but if you have more tasks than time I might be able to figure this out.

[DiegoPino]

@whikloj go for it, no worries. I had this open question

wonder if there are other miss typed properties you have seen around before making the pull request?

and then i forgot about it because i'm a flawed, over-committed, and flawed (again) human being. Do you plan to remove language at all?

[DiegoPino]

And @whikloj yep, my approach was exactly that, use the context generator code, so cool

[whikloj]

@DiegoPino I had left @language in there, but the json-ld.org/playground threw an error when parsing the resulting output because I had both @type and @language.

In the Spec I read this:

Language associations are only applied to plain strings. Typed values or values that are subject to type coercion are not language tagged.

So I guess we could leave @language if there is no @type because we would assume it is a string literal. What do you think?

[ajs6f]

That "no language for a non-string-typed literal" rule comes right out of RDF, so it's even more general than JSON-LD.

[dannylamb]

Resolved via Islandora/jsonld@36f37cb