JSON-LD simplification into JSON

[rokf]

Hello,

I'm working on a project (data space) where we're dealing with JSON-LD documents, more specifically with NGSI-LD APIs and Smart Data Models in various JSON(-LD) forms.

If you take a look at https://ngsild.org/ there's an A Simple Example section. We'd like to build a "pipeline" that could simplify any form of a valid JSON-LD document (normalised, etc.) into its simplest form (ideally pure JSON).

We'd then take that and validate it with the JSON schema for a specific data model provided by Smart Data Models (schema.json) and store it into a PostgreSQL compatible database, where we'd apply a compatible schema file for the model (schema.sql).

Let's take a look at the Device model for example. We'd like to be able to take any of the JSON-LD or pure JSON files from the model's example folder, simplify it down to its "purest" form (potentially with json-gold), validate it with the official JSON schema file for the model, and store it into a compatible PostgreSQL table, which would be created using the official SQL schema file for the model.

We're trying to figure out if json-gold is something that could help us with that. So far we've only experimented a bit and haven't yet tried all the options.

Any kind of hints / pointers / tips will be appreciated.

Thank you!

[rokf]

Alright, I believe that I've made some progress with my understanding of JSON-LD and the various operations related to JSON-LD documents.

If I for example take a JSON-LD document that's in the normalized and compacted form already nothing will happen if I run Compact against it with the appropriate (full) context - as expected.

proc := ld.NewJsonLdProcessor()
options := ld.NewJsonLdOptions("")
// Ignore the details of these options, I've been experimenting. They're not relevant to the result.
options.OutputForm = "application/json"
options.CompactArrays = true
options.UseNativeTypes = true
options.ProduceGeneralizedRdf = true
options.OmitGraph = true

compactedDoc, err := proc.Compact(
	"https://raw.githubusercontent.com/smart-data-models/dataModel.Device/refs/heads/master/Device/examples/example-normalized.jsonld",
	map[string]interface{}{
		"@context": []interface{}{
			"https://raw.githubusercontent.com/smart-data-models/dataModel.Device/master/context.jsonld",
			"https://uri.etsi.org/ngsi-ld/v1/ngsi-ld-core-context.jsonld",
		},
	},
	options,
)
if err != nil {
	panic(err)
}

ld.PrintDocument("JSON-LD compaction succeeded", compactedDoc)

This means that I'll still be left with nested objects with types and all that stuff.

{
  "@context": [
    "https://raw.githubusercontent.com/smart-data-models/dataModel.Device/master/context.jsonld",
    "https://uri.etsi.org/ngsi-ld/v1/ngsi-ld-core-context.jsonld"
  ],
  "batteryLevel": {
    "type": "Property",
    "value": 0.75
  },
  "controlledAsset": {
    "object": "urn:ngsi-ld::wastecontainer-Osuna-100",
    "type": "Relationship"
  },
  "controlledProperty": {
    "type": "Property",
    "value": [
      "fillingLevel",
      "temperature"
    ]
  },
  "dateFirstUsed": {
    "type": "Property",
    "value": {
      "@value": "2014-09-11T11:00:00Z",
      "type": "DateTime"
    }
  },
  ...
}

Flattening / simplifying / getting rid of these isn't in the scope of this library if I understand correctly since the format doesn't have anything to do with JSON-LD but rather NGSI-LD?

I'll check the NGSI-LD documentation if the process of simplifying these has a name and any specifications or official implementations.