Resource Handlers

Resources are TypeScript classes that extend the Resource base class. Override only the methods you need — every method has a safe HTTP default.

import { Resource } from "resource-machine";

class ArticleResource extends Resource {
  private article: Article | null = null;

  override async allowedMethods() {
    return ["GET", "HEAD", "PUT", "DELETE"];
  }

  override async resourceExists() {
    // Cache the DB lookup on `this` — reused by contentTypesProvided
    this.article = await db.find(this.req.params.id ?? "");
    return this.article !== null;
  }

  override async contentTypesProvided() {
    return {
      "application/json": () => JSON.stringify(this.article),
    };
  }
}

Per-Request Instantiation

The router holds the class. The decision machine calls new ArticleResource(req, res) for each incoming request. This means:

• this.req and this.res are available in every method.
• this is a natural cache for data fetched during one decision (like resourceExists) and reused in a later one (like contentTypesProvided).
• There is no shared mutable state between concurrent requests.

Available in All Methods

Defaults

If you do not override a method, it falls back to a default that produces correct HTTP behavior for a read-only resource:

See Resource Functions for the full list.