applesauce-loaders

A collection of loader classes to make loading common events from multiple relays easier.

Replaceable event loader

The ReplaceableLoader class can be used to load profiles (kind 0), contact lists (kind 3), and any other replaceable (1xxxx) or parameterized replaceable event (3xxxx)

import { Observable } from "rxjs";
import { EventStore } from "applesauce-core";
import { ReplaceableLoader } from "applesauce-loaders/loaders";

export const eventStore = new EventStore();

// Create a method to let the loaders use nostr-tools relay pool
function nostrRequest(relays: string[], filters: Filter[]) {
  return new Observable((observer) => {
    const sub = pool.subscribe(filters, {
      onevent: (event) => observer.next(event),
      oneose: () => {
        sub.close();
        observer.complete();
      },
    });

    return () => sub.close();
  });
}

// create method to load events from the cache relay
function cacheRequest(filters: Filter[]) {
  return new Observable((observer) => {
    const sub = cacheRelay.subscribe(filters, {
      onevent: (event) => observer.next(event),
      oneose: () => {
        sub.close();
        observer.complete();
      },
    });
  });
}

const replaceableLoader = new ReplaceableLoader(rxNostr, {
  bufferTime: 1000,
  // check the cache first for events
  cacheRequest: cacheRequest,
  // lookup relays are used as a fallback if the event cant be found
  lookupRelays: ["wss://purplepag.es/"],
});

// start the loader by subscribing to it
replaceableLoader.subscribe((packet) => {
  // send all loaded events to the event store
  eventStore.add(packet.event, packet.from);
});

// start loading some replaceable events
replaceableLoader.next({
  kind: 0,
  pubkey: "3bf0c63fcb93463407af97a5e5ee64fa883d107ef9e558472c4eb9aaaefa459d",
  relays: ["wss://pyramid.fiatjaf.com/"],
});

// load a parameterized replaceable event
replaceableLoader.next({
  kind: 30000,
  pubkey: "3bf0c63fcb93463407af97a5e5ee64fa883d107ef9e558472c4eb9aaaefa459d",
  identifier: "list of bad people",
  relays: ["wss://pyramid.fiatjaf.com/"],
});

// if no relays are provided only the cache and lookup relays will be checked
replaceableLoader.next({
  kind: 3,
  pubkey: "3bf0c63fcb93463407af97a5e5ee64fa883d107ef9e558472c4eb9aaaefa459d",
});

// passing a new relay will cause it to be loaded again
replaceableLoader.next({
  kind: 0,
  pubkey: "3bf0c63fcb93463407af97a5e5ee64fa883d107ef9e558472c4eb9aaaefa459d",
  relays: ["wss://relay.westernbtc.com/"],
});

// or force it to load it again from the same relays
replaceableLoader.next({
  kind: 0,
  pubkey: "3bf0c63fcb93463407af97a5e5ee64fa883d107ef9e558472c4eb9aaaefa459d",
  relays: ["wss://pyramid.fiatjaf.com/"],
  force: true,
});
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