@rdfjs/serializer-jsonld-ext

@rdfjs/serializer-jsonld-ext

JSON-LD serializer that implements the RDF/JS Sink interface and supports different output styles. This package handles the stream processing and uses jsonld.js for the actual serialization process.

Usage

The package exports the serializer as a class, so an instance must be created before it can be used. The .import method, as defined in the RDF/JS specification, must be called to do the actual serialization. It expects a quad stream as argument. The method will return a stream which emits the JSON-LD as a plain object or string.

The constructor accepts an options object with the following optional keys:

• baseIRI: A base IRI given as NamedNode, URL, or string object.
• context: JSON-LD context that will be used for compact, flatten or frame. The context must be given as a plain object. By default {} is used.
• compact: If this flag is true, the jsonld.js compact will be used to process the output.
• flatten: If this flag is true, the jsonld.js flatten will be used to process the output.
• frame: If this flag is true, the jsonld.js frame will be used to process the output.
• skipContext: Removes the @context property from the output. Useful for HTTP server when the media type application/json is used and a context is provided as header link.
• encoding: Defines the encoding of the output. Supported encodings are string and object. By default object is used.
• prettyPrint: Enables pretty printing for string encoding.

It's also possible to pass options as second argument to the .import method. The options from the constructor and the .import method will be merged together.

Example

This example shows how to create a serializer instance and how to feed it with a stream of quads. The output will be processed with compact using the given context and baseIRI. The string emitted by the serializer will be written to the console.

import rdf from '@rdfjs/data-model'
import { Readable } from 'readable-stream'
import SerializerJsonld from '@rdfjs/serializer-jsonld-ext'

const context = {
  '@vocab': 'http://schema.org/'
}

const serializerJsonld = new SerializerJsonld({
  baseIRI: 'http://example.org/',
  context,
  compact: true,
  encoding: 'string',
  prettyPrint: true
})

const input = new Readable({
  objectMode: true,
  read: () => {
    input.push(rdf.quad(
      rdf.namedNode('http://example.org/sheldon-cooper'),
      rdf.namedNode('http://schema.org/givenName'),
      rdf.literal('Sheldon')))
    input.push(rdf.quad(
      rdf.namedNode('http://example.org/sheldon-cooper'),
      rdf.namedNode('http://schema.org/familyName'),
      rdf.literal('Cooper')))
    input.push(rdf.quad(
      rdf.namedNode('http://example.org/sheldon-cooper'),
      rdf.namedNode('http://schema.org/knows'),
      rdf.namedNode('http://example.org/amy-farrah-fowler')))
    input.push(null)
  }
})

const output = serializerJsonld.import(input)

output.on('data', jsonld => {
  console.log(jsonld)
})

/* output:

{
  "@context": {
    "@vocab": "http://schema.org/",
    "@base": "http://example.org/"
  },
  "@id": "sheldon-cooper",
  "familyName": "Cooper",
  "givenName": "Sheldon",
  "knows": {
    "@id": "amy-farrah-fowler"
  }
}
*/