Merge pull request #364 from sij411/docs/custom-collection (33745bc7) · Commits · sc07 / Fedify Patched

examples/README.md

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		@@ -6,6 +6,7 @@ Currently, there is only few examples, but more examples will be
		added in the future.[^1]

		- [Actor lookup CLI](./actor-lookup-cli/)
		- [Custom collections example](./custom-collections/)
		- [Federated single-user blog](./blog/)
		- [Federated microblog](https://github.com/fedify-dev/microblog), which is
		a final result of

examples/custom-collections/README.md

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		Custom collections example
		==========================

		This example demonstrates how to implement custom collections in Fedify.
		Custom collections allow you to define your own ActivityPub collections with
		custom logic for dispatching items and counting collection sizes.

		~~~~ sh
		deno task codegen # At very first time only
		deno run -A ./main.ts
		~~~~

examples/custom-collections/main.ts

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		import { createFederation, MemoryKvStore, Note } from "@fedify/fedify";

		// Mock data - in a real application, this would query your database
		const POSTS = [
		new Note({
		id: new URL("https://example.com/posts/post-1"),
		content: "ActivityPub is a decentralized social networking protocol...",
		tags: [
		new URL("https://example.com/tags/ActivityPub"),
		new URL("https://example.com/tags/Decentralization"),
		],
		}),

		new Note({
		id: new URL("https://example.com/posts/post-2"),
		content: "Fedify makes it easy to build federated applications...",
		}),

		new Note({
		id: new URL("https://example.com/posts/post-3"),
		content: "WebFinger is a protocol for discovering information...",
		tags: [new URL("https://example.com/tags/ActivityPub")],
		}),

		new Note({
		id: new URL("https://example.com/posts/post-4"),
		content: "HTTP Signatures provide authentication for ActivityPub...",
		}),

		new Note({
		id: new URL("https://example.com/posts/post-5"),
		content: "Understanding ActivityPub's data model is crucial...",
		}),
		];

		function getTagFromUrl(url: string): string {
		const parts = url.split("/");
		return parts[parts.length - 1];
		}

		function getTaggedPostsByTag(tag: string): Note[] {
		return POSTS
		.filter((post) => {
		if (!post.tagIds) {
		return false;
		}
		return post.tagIds.some((tagId) => {
		return getTagFromUrl(tagId.toString()) === tag;
		});
		});
		}

		async function demonstrateCustomCollection(): Promise<Response> {
		// Federation instance created for demonstration
		const federation = createFederation<void>({ kv: new MemoryKvStore() });

		federation.setCollectionDispatcher(
		"TaggedPosts",
		Note,
		"/users/{userId}/tags/{tag}",
		(
		_ctx: { url: URL },
		values: Record<string, string>,
		cursor: string \| null,
		) => {
		if (!values.tag) {
		throw new Error("Missing userId or tag in values");
		}

		// Normally here you would look up posts from a database by user ID and tag name:
		const posts = getTaggedPostsByTag(values.tag);

		if (cursor != null) {
		const idx = Number.parseInt(cursor, 10);
		if (Number.isNaN(idx) \|\| idx > posts.length \|\| idx < 0) {
		return { items: [], nextCursor: null, prevCursor: null };
		}
		return {
		items: idx < posts.length ? [posts[idx]] : [],
		nextCursor: idx < posts.length - 1 ? (idx + 1).toString() : null,
		prevCursor: idx > 0 ? (idx - 1).toString() : null,
		};
		}
		return { items: posts, nextCursor: null, prevCursor: null };
		},
		).setCounter((_ctx, values) => {
		// Return the total count of tagged posts
		const count = getTaggedPostsByTag(values.tag).length;
		return count;
		});

		return await federation.fetch(
		new Request(
		"https://example.com/users/123/tags/ActivityPub",
		{
		headers: {
		Accept: "application/activity+json",
		},
		},
		),
		{
		contextData: undefined,
		},
		);
		}

		if (import.meta.main) {
		const response = await demonstrateCustomCollection();

		if (response.ok) {
		const jsonResponse = await response.json();
		console.log("Custom collection data:", jsonResponse);
		} else {
		const errorText = await response.text();
		console.log("Error response:", errorText);
		}
		}