@fedify/fedify/esm/compat/transformers.js

An ActivityPub server framework

import * as dntShim from "../_dnt.shims.js";
import { getLogger } from "@logtape/logtape";
const logger = getLogger(["fedify", "compat", "transformers"]);
/**
 * An activity transformer that assigns a new random ID to an activity if it
 * does not already have one.  This is useful for ensuring that activities
 * have an ID before they are sent to other servers.
 *
 * The generated ID is an origin URI with a fragment which contains an activity
 * type name with a random UUID:
 *
 * ```
 * https://example.com/#Follow/12345678-1234-5678-1234-567812345678
 * ```
 *
 * @typeParam TContextData The type of the context data.
 * @param activity The activity to assign an ID to.
 * @param context The context of the activity.
 * @return The activity with an ID assigned.
 * @since 1.4.0
 */
export function autoIdAssigner(activity, context) {
    if (activity.id != null)
        return activity;
    const id = new URL(`/#${activity.constructor.name}/${dntShim.crypto.randomUUID()}`, context.origin);
    logger.warn("As the activity to send does not have an id, a new id {id} has " +
        "been generated for it.  However, it is recommended to explicitly " +
        "set the id for the activity.", { id: id.href });
    return activity.clone({ id });
}
/**
 * An activity transformer that dehydrates the actor property of an activity
 * so that it only contains the actor's URI.  For example, suppose we have an
 * activity like this:
 *
 * ```typescript
 * import { Follow, Person } from "@fedify/fedify/vocab";
 * const input = new Follow({
 *   id: new URL("http://example.com/activities/1"),
 *   actor: new Person({
 *     id: new URL("http://example.com/actors/1"),
 *     name: "Alice",
 *     preferredUsername: "alice",
 *   }),
 *   object: new Person({
 *     id: new URL("http://example.com/actors/2"),
 *     name: "Bob",
 *     preferredUsername: "bob",
 *   }),
 * });
 * ```
 *
 * The result of applying this transformer would be:
 *
 * ```typescript
 * import { Follow, Person } from "@fedify/fedify/vocab";
 * const output = new Follow({
 *   id: new URL("http://example.com/activities/1"),
 *   actor: new URL("http://example.com/actors/1"),
 *   object: new Person({
 *     id: new URL("http://example.com/actors/2"),
 *     name: "Bob",
 *     preferredUsername: "bob",
 *   }),
 * });
 * ```
 *
 * As some ActivityPub implementations like Threads fail to deal with inlined
 * actor objects, this transformer can be used to work around this issue.
 * @typeParam TContextData The type of the context data.
 * @param activity The activity to dehydrate the actor property of.
 * @param context The context of the activity.
 * @returns The dehydrated activity.
 * @since 1.4.0
 */
export function actorDehydrator(activity, _context) {
    if (activity.actorIds.length < 1)
        return activity;
    return activity.clone({
        actors: activity.actorIds,
    });
}
/**
 * Gets the default activity transformers that are applied to all outgoing
 * activities.
 * @typeParam TContextData The type of the context data.
 * @returns The default activity transformers.
 * @since 1.4.0
 */
export function getDefaultActivityTransformers() {
    return [
        autoIdAssigner,
        actorDehydrator,
    ];
}