Fix getCollection return new instance in prod (#8022)

bluwy · web-flow · commit c23377caafbc · 2023-08-10T22:13:32.000+08:00
diff --git a/.changeset/smart-nails-push.md b/.changeset/smart-nails-push.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Always return a new array instance from `getCollection` in prod
diff --git a/packages/astro/src/content/runtime.ts b/packages/astro/src/content/runtime.ts
@@ -69,7 +69,8 @@ export function createGetCollection({
 		// Cache `getCollection()` calls in production only
 		// prevents stale cache in development
 		if (import.meta.env.PROD && cacheEntriesByCollection.has(collection)) {
-			entries = cacheEntriesByCollection.get(collection)!;
+			// Always return a new instance so consumers can safely mutate it
+			entries = [...cacheEntriesByCollection.get(collection)!]
 		} else {
 			entries = await Promise.all(
 				lazyImports.map(async (lazyImport) => {
diff --git a/packages/astro/test/content-collections-render.test.js b/packages/astro/test/content-collections-render.test.js
@@ -168,6 +168,22 @@ describe('Content Collections - render()', () => {
 			expect(h2).to.have.a.lengthOf(1);
 			expect(h2.attr('data-components-export-applied')).to.equal('true');
 		});
+
+		it('getCollection should return new instances of the array to be mutated safely', async () => {
+			const app = await fixture.loadTestAdapterApp();
+
+			let request = new Request('http://example.com/sort-blog-collection');
+			let response = await app.render(request);
+			let html = await response.text();
+			let $ = cheerio.load(html);
+			expect($('li').first().text()).to.equal('With Layout Prop');
+
+			 request = new Request('http://example.com/');
+			 response = await app.render(request);
+			 html = await response.text();
+			 $ = cheerio.load(html);
+			expect($('li').first().text()).to.equal('Hello world');
+		})
 	});
 
 	describe('Dev - SSG', () => {
diff --git a/packages/astro/test/fixtures/content/src/pages/sort-blog-collection.astro b/packages/astro/test/fixtures/content/src/pages/sort-blog-collection.astro
@@ -0,0 +1,22 @@
+---
+import { getCollection } from 'astro:content';
+
+const blog = await getCollection('blog');
+
+// Sort descending by title, make sure mutating `blog` doesn't mutate other pages that call `getCollection` too
+blog.sort((a, b) => a.data.title < b.data.title ? 1 : -1)
+---
+<html>
+<head>
+	<title>Index</title>
+</head>
+<body>
+	<h1>Blog Posts</h1>
+
+	<ul>
+		{blog.map(post => (
+			<li>{ post.data.title }</li>
+		))}
+	</ul>
+</body>
+</html>

-Original file line number
+Diff line change
@@ @@ -0,0 +1,5 @@ @@
 +---
 +'astro': patch
 +---
++
 +Always return a new array instance from `getCollection` in prod