Resource

A resource turns a particular data schema to an interactive entity repository. In principle, a resource is a collection of data entities that conform to the specified schema. Through resources you can find or update data easily.

In background, resources handle building and executing SPARQL queries, data retrieval and transformation according to the data schema.

Creating a resource

A resource requires a schema, a context, and a query engine. If you do not specify context or engine, default ones will be used.

import { type Context, createResource } from "ldkit";

const context: Context = {
  sources: ["https://example.com/sparql"],
};

const resource = createResource(MySchema, context); // will use default query engine

Resource usage

The examples below show a simple Person resource on top of DBpedia - a collection of entities of type dbo:Person that have a name, an abstract and a birth date.

Create a resource to query persons

import { type Context, createResource } from "ldkit";
import { dbo, rdfs, xsd } from "ldkit/namespaces";

const context: Context = {
  sources: ["https://example.com/sparql"],
};

// Create a schema
const PersonSchema = {
  "@type": dbo.Person,
  name: rdfs.label,
  abstract: dbo.abstract,
  birthDate: { "@id": dbo.birthDate, "@type": xsd.date },
} as const;

// Create a resource using the data schema and context above
const Person = createResource(PersonSchema, context);

List all matched persons

// List all persons
const persons = await Person.find();
for (const person of persons) {
  console.log(person.name); // string
  console.log(person.birthDate); // Date
}

// Get total count of all persons
const count = await Person.count();
console.log(count); // number

Get a particular entity

// Get a particular person identified by IRI
const ada = await Person.findByIri("http://dbpedia.org/resource/Ada_Lovelace");
console.log(ada?.name); // string "Ada Lovelace"
console.log(ada?.birthDate); // Date object of 1815-12-10

Data manipulation - insert, update and delete

When modifying data, you can use the native data format specified by the data schema. The data gets transformed to RDF behind the scenes.

// Insert a new person
Person.insert({
  $id: "http://dbpedia.org/resource/Alan_Turing",
  name: "Alan Turing",
  birthDate: new Date("1912-06-23"),
});

// Modify a person's name
Person.update({
  $id: "http://dbpedia.org/resource/Alan_Turing",
  name: "Not Alan Turing",
});

// Delete a person
Person.delete("http://dbpedia.org/resource/Alan_Turing");

Data manipulation - insert or update raw data

If the provided data update methods are not sufficient, there are special methods insertData and deleteData where you can pass raw data in RDF data format according to the RDF/JS data specification. You can use the included DataFactory implementation, or use your own.

import { DataFactory } from "ldkit/rdf";

const df = new DataFactory();
const quad = df.quad(
  df.namedNode("http://dbpedia.org/resource/Alan_Turing")
  df.namedNode(rdfs.label),
  df.literal("Maybe Not Alan Turing")
);
await Person.insertData([quad]); // quad added to the database