[Content collections] Support type guards on getCollection() filter (…

…#5970) * fix: respect type guards from collection filter * chore: changeset
withastro · Jan 25, 2023 · dabce6b · dabce6b
1 parent b53e071
commit dabce6b
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Showing 2 changed files with 8 additions and 3 deletions.
diff --git a/.changeset/strong-hotels-sort.md b/.changeset/strong-hotels-sort.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Add type guard support to filters on `getCollection()`
diff --git a/packages/astro/src/content/template/types.d.ts b/packages/astro/src/content/template/types.d.ts
@@ -44,10 +44,10 @@ declare module 'astro:content' {
 	): E extends ValidEntrySlug<C>
 		? Promise<CollectionEntry<C>>
 		: Promise<CollectionEntry<C> | undefined>;
-	export function getCollection<C extends keyof typeof entryMap>(
+	export function getCollection<C extends keyof typeof entryMap, E extends CollectionEntry<C>>(
 		collection: C,
-		filter?: (data: CollectionEntry<C>) => boolean
-	): Promise<CollectionEntry<C>[]>;
+		filter?: (entry: CollectionEntry<C>) => entry is E
+	): Promise<E[]>;
 
 	type InferEntrySchema<C extends keyof typeof entryMap> = import('astro/zod').infer<
 		Required<ContentConfig['collections'][C]>['schema']