Working with arrays

The LDkit library provides a simple and intuitive way to work with arrays in linked data contexts. This section focuses on the manipulation of array elements, including adding and removing elements.

Initializing and Defining Models

Before working with arrays, initialize your data source and define your data schema. Examples below make use of a Director schema, having a director name and a list of movies:

import { type Context, createLens, createNamespace } from "ldkit";

// Create a custom namespace
const ns = createNamespace(
  {
    "iri": "http://ns/",
    "prefix": "ns",
    "terms": [
      "name",
      "movie",
    ],
  } as const,
);

// Create a schema
const DirectorSchema = {
  name: ns.name,
  movies: {
    "@id": ns.movie,
    "@array": true,
  },
} as const;

const Directors = createLens(DirectorSchema);

// Add a director with a an empty list of movies
await Directors.insert({
  $id: "https://Quentin_Tarantino",
  name: "Quentin Tarantino",
  movies: [],
});

Updating arrays

To modify array elements, use the Lens.update method. This method supports different operations.

Setting an Array: Replace the entine array with a new set of elements

await Directors.update({
  $id: "https://Quentin_Tarantino",
  movies: {
    $set: ["Pulp Fiction", "Reservoir Dogs"],
  },
});

Adding Elements: Append new elements to the array

await Directors.update({
  $id: "https://Quentin_Tarantino",
  movies: {
    $add: ["Kill Bill", "Kill Bill 2"],
  },
}); // The `movies` is now ["Pulp Fiction", "Reservoir Dogs", "Kill Bill", "Kill Bill 2"]

Removing Elements: Remove specific elements from the array

await Directors.update({
  $id: "https://Quentin_Tarantino",
  movies: {
    $remove: ["Reservoir Dogs"],
  },
}); // The `movies` is now ["Pulp Fiction", "Kill Bill", "Kill Bill 2"]

Setting an Empty Array: Clear all elements from the array

await Directors.update({
  $id: "https://Quentin_Tarantino",
  movies: {
    $set: [], // Remove all movies
  },
});

Working with Multiple Entitites

You can also perform array updates on multiple entities simultaneously using a single SPARQL query.

await Directors.insert({
  $id: "https://David_Fincher",
  name: "David Fincher",
  movies: ["Fight Club", "The Social Network"],
});

await Directors.update({
  $id: "https://Quentin_Tarantino",
  movies: {
    $set: ["Inglorious Basterds"],
  },
}, {
  $id: "https://David_Fincher",
  movies: {
    $add: ["The Curious Case of Benjamin Button"],
  },
});