@treecg/tree-metadata-extraction

TREE metadata extraction

This library handles the extraction of TREE metadata from RDF data.

Installation

Node

const extractMetadata = require('@treecg/tree-metadata-extraction').extractMetadata

typescript

import { extractMetadata } from '@treecg/tree-metadata-extraction';

Usage

// quads is an array of RDF Quads (RDF.Quad[])
const metadata = extractMetadata(quads)

// Retrieve extracted collections metadata
for (const collectionId of metadata.collections.keys()) {
  const collection = metadata.collections.get(collectionId)
}

// Retrieve extracted nodes metadata
for (const nodeId of metadata.nodes.keys()) {
  const node = metadata.nodes.get(nodeId)
}

// Retrieve extracted relations metadata
for (const relationId of metadata.relations.keys()) {
  const relation = metadata.relations.get(relationId)
}

Extracted metadata

In this section, the extracted fields per class are listed. In the case an Object is returned, it can have arbitrary fields that are not listed below.

Object	Metadata field	type	referenced object type
Collection	@id	string
	@type	[ string ]
	view	[ URI ]	Node
	subset	[ URI ]	Node
	member	[ URI ]	Member
	shape	[ Shape ]
	totalItems	[ Literal ]
	import	[ URI ]
	importStream	[ URI ]
	conditionalImport	[ ConditionalImport ]
	...	[ any ]
Node	@id	string
	@type	[ string ]
	relation	[ URI ]	Relation
	search	[ object ]
	retentionPolicy	[ RetentionPolicy ]
	import	[ object ]
	importStream	[ object ]
	conditionalImport	[ ConditionalImport ]
	...	[ any ]
Relation	@id	string
	@type	[ string ]
	remainingItems	[ Literal ]
	path	[ object ]	shacl:propertyPath
	value	[ object ]
	node	[ URI ]	Node
	import	[ URI ]
	importStream	[ URI ]
	conditionalImport	[ ConditionalImport ]
Member	...	[ any ]
Shape	...	[ any ]	shacl:NodeShape / shex:Shape
IriTemplate	...	[ any ]	hydra:IriTemplate
ConditionalImport	path	[ object ]	shacl:propertyPath
	import	[ URI ]
	importStream	[ URI ]
RetentionPolicy	@type	[ string ]
	amount	[ Literal ]
	versionKey	[ object ]
	path	[ object ]	shacl:propertyPath
	value	[ object ]
Literal	@value	[ string ]
	@type	[ string ]
	@language	[ string ]
URI	@id	string
object	@id	string
	...	[ any ]

Note: Blank node URIs can be returned as a URI. 
We expect any additional data used in combination with the extracted metadata to be retrieved from the same rdfjs data factory.

Examples

Retrieve the ids of all members of all collections available in the quad array.

// Parse the input into a quad array
const quads = parse(input)

// Extract the tree metadata from the quad array
const metadata = extractMetadata(quads)

const memberIds = []

// Retrieve extracted collections metadata
for (const collectionId of metadata.collections.keys()) {
  // Get the collection object
  const collection = metadata.collections.get(collectionId)
  // Map the member URIs to extract the @id values
  const memberURIs = collection.member.map(uri => uri["@id"])
  // Store the @id values
  memberIds = memberIds.concat(memberURIs)
}

return memberIds