feat: experimental content collection JSON schemas

.changeset/slow-items-heal.md

@@ -0,0 +1,34 @@
+---
+"astro": minor
+---
+
+Adds experimental JSON Schema support for content collections of with `type: 'data'`.
+
+To enable this feature, add the experimental flag:
+
+```
+{
+  experimental: {
+    contentCollectionJSONSchemas: true,
+  },
+}
+```
+
+To be able to use the schemas, you need to adapt your zod definition and reference it inside the json manually:
+
+```diff
+const test = defineCollection({
+	type: 'data',
+	schema: z.object({
++		"$schema": z.string().optional(),
+    test: z.string()
+	}),
+});
+```
+
+```json
+{
+  "$schema": "../../../.astro/schemas/collections/test.json",
+  "test": "test"
+}
+```

packages/astro/package.json

@@ -176,7 +176,8 @@
     "vitefu": "^0.2.5",
     "which-pm": "^2.1.1",
     "yargs-parser": "^21.1.1",
-    "zod": "^3.22.4"
+    "zod": "^3.22.4",
+    "zod-to-json-schema": "^3.22.4"
   },
   "optionalDependencies": {
     "sharp": "^0.32.6"

packages/astro/src/@types/astro.ts

@@ -1640,6 +1640,25 @@ export interface AstroUserConfig {
 		 */
 		contentCollectionCache?: boolean;
 
+		/**
+		 * @docs
+		 * @name experimental.contentCollectionJSONSchema
+		 * @type {boolean}
+		 * @default `false`
+		 * @version 4.5.0
+		 * @description
+		 * Enables generation of JSON Schema files for content collections of type `data`.
+		 *
+		 * ```js
+		 * {
+		 * 	experimental: {
+		 * 		contentCollectionJSONSchema: true,
+		 * 	},
+		 * }
+		 * ```
+		 */
+		contentCollectionJSONSchema?: boolean;
+
 		/**
 		 * @docs
 		 * @name experimental.clientPrerender

packages/astro/src/content/types-generator.ts

@@ -1,5 +1,6 @@
 import glob from 'fast-glob';
 import { bold, cyan } from 'kleur/colors';
+import { zodToJsonSchema } from 'zod-to-json-schema';
 import type fsMod from 'node:fs';
 import * as path from 'node:path';
 import { fileURLToPath, pathToFileURL } from 'node:url';
@@ -310,6 +311,7 @@ export async function createContentTypesGenerator({
 				contentConfig: observable.status === 'loaded' ? observable.config : undefined,
 				contentEntryTypes: settings.contentEntryTypes,
 				viteServer,
+				settings
 			});
 			invalidateVirtualMod(viteServer);
 		}
@@ -352,6 +354,7 @@ async function writeContentFiles({
 	contentEntryTypes,
 	contentConfig,
 	viteServer,
+	settings
 }: {
 	fs: typeof fsMod;
 	contentPaths: ContentPaths;
@@ -360,6 +363,7 @@ async function writeContentFiles({
 	contentEntryTypes: Pick<ContentEntryType, 'contentModuleTypes'>[];
 	contentConfig?: ContentConfig;
 	viteServer: Pick<ViteDevServer, 'hot'>;
+	settings: AstroSettings;
 }) {
 	let contentTypesStr = '';
 	let dataTypesStr = '';
@@ -419,6 +423,29 @@ async function writeContentFiles({
 				for (const entryKey of Object.keys(collection.entries).sort()) {
 					const dataType = collectionConfig?.schema ? `InferEntrySchema<${collectionKey}>` : 'any';
 					dataTypesStr += `${entryKey}: {\n	id: ${entryKey};\n  collection: ${collectionKey};\n  data: ${dataType}\n};\n`;
+					if(settings.config.experimental.contentCollectionJSONSchema) {
+						if (collectionConfig) {
+							// writing inside loop makes sense for the json schema, since we want to have a file per collection
+							const collectionSchemasDir = new URL('./schemas/collections/', contentPaths.cacheDir);
+							if (!fs.existsSync(collectionSchemasDir)) {
+								fs.mkdirSync(collectionSchemasDir, { recursive: true });
+							}
+
+							if (collectionConfig?.schema)
+								await fs.promises.writeFile(
+									new URL(`./${collectionKey.replace(/"/g, '')}.json`, collectionSchemasDir),
+									JSON.stringify(
+										zodToJsonSchema(collectionConfig?.schema, {
+											name: collectionKey.replace(/"/g, ''),
+											markdownDescription: true,
+											errorMessages: true,
+										}),
+										null,
+										2
+									)
+								);
+						}
+					}
 				}
 				dataTypesStr += `};\n`;
 				break;

packages/astro/src/core/config/schema.ts

@@ -60,6 +60,7 @@ const ASTRO_CONFIG_DEFAULTS = {
 	experimental: {
 		optimizeHoistedScript: false,
 		contentCollectionCache: false,
+		contentCollectionJSONSchema: false,
 		clientPrerender: false,
 		globalRoutePriority: false,
 		i18nDomains: false,
@@ -492,6 +493,10 @@ export const AstroConfigSchema = z.object({
 				.boolean()
 				.optional()
 				.default(ASTRO_CONFIG_DEFAULTS.experimental.contentCollectionCache),
+			contentCollectionJSONSchema: z
+				.boolean()
+				.optional()
+				.default(ASTRO_CONFIG_DEFAULTS.experimental.contentCollectionJSONSchema),
 			clientPrerender: z
 				.boolean()
 				.optional()