fix: pass emulated entry to getCollection filter function (#12875)

* fix: pass emulated entry to getCollection filter function

* Add test

4 files changed, 32 insertions, 8 deletions

diff --git a/.changeset/rotten-baboons-roll.md b/.changeset/rotten-baboons-roll.md
new file mode 100644
index 000000000..e7e142259
--- /dev/null
+++ b/.changeset/rotten-baboons-roll.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fixes a bug in emulated legacy collections where the entry passed to the getCollection filter function did not include the legacy entry fields.
diff --git a/packages/astro/src/content/runtime.ts b/packages/astro/src/content/runtime.ts
index ea1527106..aa6b63be3 100644
--- a/packages/astro/src/content/runtime.ts
+++ b/packages/astro/src/content/runtime.ts
@@ -96,15 +96,20 @@ export function createGetCollection({
 			for (const rawEntry of store.values<DataEntry>(collection)) {
 				const data = updateImageReferencesInData(rawEntry.data, rawEntry.filePath, imageAssetMap);
 
-				const entry = {
+				let entry = {
 					...rawEntry,
 					data,
 					collection,
 				};
+
+				if (entry.legacyId) {
+					entry = emulateLegacyEntry(entry);
+				}
+
 				if (hasFilter && !filter(entry)) {
 					continue;
 				}
-				result.push(entry.legacyId ? emulateLegacyEntry(entry) : entry);
+				result.push(entry);
 			}
 			return result;
 		} else {
@@ -272,19 +277,18 @@ type DataEntryResult = {
 
 type EntryLookupObject = { collection: string; id: string } | { collection: string; slug: string };
 
-function emulateLegacyEntry(entry: DataEntry) {
+function emulateLegacyEntry({ legacyId, ...entry }: DataEntry & { collection: string }) {
 	// Define this first so it's in scope for the render function
 	const legacyEntry = {
 		...entry,
-		id: entry.legacyId!,
+		id: legacyId!,
 		slug: entry.id,
 	};
-	delete legacyEntry.legacyId;
 	return {
 		...legacyEntry,
 		// Define separately so the render function isn't included in the object passed to `renderEntry()`
 		render: () => renderEntry(legacyEntry),
-	};
+	} as ContentEntryResult;
 }
 
 export function createGetEntry({
@@ -334,7 +338,7 @@ export function createGetEntry({
 			const { default: imageAssetMap } = await import('astro:asset-imports');
 			entry.data = updateImageReferencesInData(entry.data, entry.filePath, imageAssetMap);
 			if (entry.legacyId) {
-				return { ...emulateLegacyEntry(entry), collection } as ContentEntryResult;
+				return emulateLegacyEntry({ ...entry, collection });
 			}
 			return {
 				...entry,
diff --git a/packages/astro/test/fixtures/legacy-content-collections/src/pages/collections.json.js b/packages/astro/test/fixtures/legacy-content-collections/src/pages/collections.json.js
index 67bafdb93..16350c5ad 100644
--- a/packages/astro/test/fixtures/legacy-content-collections/src/pages/collections.json.js
+++ b/packages/astro/test/fixtures/legacy-content-collections/src/pages/collections.json.js
@@ -9,8 +9,17 @@ export async function GET() {
 	const withUnionSchema = stripAllRenderFn(await getCollection('with-union-schema'));
 	const withSymlinkedContent = stripAllRenderFn(await getCollection('with-symlinked-content'));
 	const withSymlinkedData = stripAllRenderFn(await getCollection('with-symlinked-data'));
+	const filtered = stripAllRenderFn(await getCollection('without-config', (entry) => entry.slug));
 
 	return new Response(
-		devalue.stringify({ withoutConfig, withSchemaConfig, withSlugConfig, withUnionSchema, withSymlinkedContent, withSymlinkedData }),
+		devalue.stringify({
+			withoutConfig,
+			withSchemaConfig,
+			withSlugConfig,
+			withUnionSchema,
+			withSymlinkedContent,
+			withSymlinkedData,
+			filtered,
+		}),
 	);
 }
diff --git a/packages/astro/test/legacy-content-collections.test.js b/packages/astro/test/legacy-content-collections.test.js
index 613d76e1e..e4327ceb3 100644
--- a/packages/astro/test/legacy-content-collections.test.js
+++ b/packages/astro/test/legacy-content-collections.test.js
@@ -55,6 +55,12 @@ describe('Legacy Content Collections', () => {
 				);
 			});
 
+			it('Passes legacy entry to filter function', async () => {
+				assert.ok(json.hasOwnProperty('filtered'));
+				assert.ok(Array.isArray(json.filtered));
+				assert.ok(json.filtered.length > 0);
+			});
+
 			it('Returns `with schema` collection', async () => {
 				assert.ok(json.hasOwnProperty('withSchemaConfig'));
 				assert.equal(Array.isArray(json.withSchemaConfig), true);