feat: improve api for PageIterator and add new ChunkPageIterator

MellKam · Feb 20, 2024 · 025f58d · 025f58d
1 parent cf109b4
commit 025f58d
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Showing 3 changed files with 255 additions and 106 deletions.
diff --git a/endpoints/general.types.ts b/endpoints/general.types.ts
@@ -46,12 +46,12 @@ export type CursorPagingObject<TItem> = {
 		/**
 		 * The cursor to use as key to find the next page of items.
 		 */
-		after: string;
+		after?: string;
 		/**
 		 * The cursor to use as key to find the previous page of items.
 		 */
-		before: string;
-	};
+		before?: string;
+	} | null;
 	/**
 	 * The total number of items available to return.
 	 */

diff --git a/pagination.test.ts b/pagination.test.ts
@@ -1,52 +1,64 @@
-import { PageIterator } from "./pagination.ts";
+import { CursorPageIterator, PageIterator } from "./pagination.ts";
 import { assertEquals } from "std/assert/mod.ts";
 
 type MockArtist = {
-	id: number;
+	id: string;
 	type: "artist";
 	name: string;
 };
 const totalMockItems = 50;
-const mockArtists: MockArtist[] = Array(totalMockItems).fill(0).map((
-	_,
-	i,
-) => ({
-	id: i,
-	type: "artist",
-	name: "Radiohead",
-}));
+const mockArtists: MockArtist[] = Array(totalMockItems)
+	.fill(0)
+	.map((_, i) => ({
+		id: i.toString(),
+		type: "artist",
+		name: "Radiohead",
+	}));
 
 Deno.test("PageIterator: asyncIterator", async () => {
-	const pageIterator = new PageIterator((opts) => {
-		const limit = opts.limit || 20;
-		const offset = opts.offset || 0;
+	const pageIterator = new PageIterator((offset) => {
+		const limit = 20;
 
 		return Promise.resolve({
-			href: "#",
 			items: mockArtists.slice(offset, offset + limit),
-			offset,
 			limit,
 			next: offset + limit < totalMockItems ? "http://example.com" : null,
-			previous: offset > 0 ? "http://example.com" : null,
 			total: totalMockItems,
 		});
 	});
 
-	const iter = pageIterator.asyncIterator();
+	const iter1 = pageIterator[Symbol.asyncIterator]();
 
 	for (let i = 0; i < totalMockItems; i++) {
-		assertEquals(await iter.next(), { done: false, value: mockArtists[i] });
+		const result = await iter1.next();
+		assertEquals(result, {
+			done: false,
+			value: mockArtists[i],
+		});
 	}
-	assertEquals(await iter.next(), {
+	assertEquals(await iter1.next(), {
+		done: true,
+		value: null,
+	});
+
+	const iter2 = pageIterator[Symbol.asyncIterator](-totalMockItems);
+
+	for (let i = 0; i < totalMockItems; i++) {
+		const result = await iter2.next();
+		assertEquals(result, {
+			done: false,
+			value: mockArtists[i],
+		});
+	}
+	assertEquals(await iter2.next(), {
 		done: true,
 		value: null,
 	});
 });
 
 Deno.test("PageIterator: collect", async () => {
-	const pageIterator = new PageIterator((opts) => {
-		const limit = opts.limit || 20;
-		const offset = opts.offset || 0;
+	const pageIterator = new PageIterator((offset) => {
+		const limit = 20;
 
 		return Promise.resolve({
 			href: "#",
@@ -61,4 +73,58 @@ Deno.test("PageIterator: collect", async () => {
 
 	const items = await pageIterator.collect();
 	assertEquals(items, mockArtists);
+
+	const items2 = await pageIterator.collect(10);
+	assertEquals(items2, mockArtists.slice(0, 10));
+});
+
+Deno.test("CursorPageIterator: asyncIterator", async () => {
+	const cursorPageIterator = new CursorPageIterator((opts) => {
+		const limit = 20;
+
+		if (opts.after === undefined) {
+			return Promise.resolve({
+				items: mockArtists.slice(0, limit),
+				next: limit < totalMockItems ? "http://example.com" : null,
+				cursors: {
+					after: mockArtists.at(limit - 1)?.id,
+				},
+			});
+		}
+
+		const afterArtistIndex = mockArtists.findIndex((artist) =>
+			artist.id === opts.after
+		);
+		if (afterArtistIndex === -1) {
+			throw new Error("Invalid cursor");
+		}
+
+		return Promise.resolve({
+			items: mockArtists.slice(
+				afterArtistIndex + 1,
+				afterArtistIndex + 1 + limit,
+			),
+			next: afterArtistIndex + limit < totalMockItems
+				? "http://example.com"
+				: null,
+			cursors: {
+				after: mockArtists.at(afterArtistIndex + limit)?.id,
+			},
+		});
+	});
+
+	const iter = cursorPageIterator[Symbol.asyncIterator]();
+
+	for (let i = 0; i < totalMockItems; i++) {
+		const result = await iter.next();
+		console.log(result);
+		assertEquals(result, {
+			done: false,
+			value: mockArtists[i],
+		});
+	}
+	assertEquals(await iter.next(), {
+		done: true,
+		value: null,
+	});
 });