Allow using image as an external import

packages/astro/src/content/template/virtual-mod.mjs

@@ -5,7 +5,8 @@ import {
 	createGetEntryBySlug,
 } from 'astro/content/runtime';
 
-export { z } from 'astro/zod';
+import { z } from 'astro/zod';
+export { z };
 
 export function defineCollection(config) {
 	return config;
@@ -38,3 +39,49 @@ export const getEntryBySlug = createGetEntryBySlug({
 	getCollection,
 	collectionToRenderEntryMap,
 });
+
+export function image() {
+	let astroContext = undefined;
+	const str = z.string();
+	const _parse = str._parse;
+	str._parse = function(ctx){
+		// Walk up the parents until we find the Astro context.
+		let parent = ctx.parent;
+		while(parent) {
+			if(parent.astro) {
+				astroContext = parent.astro;
+				break;
+			} else {
+				parent = parent.parent;
+			}
+		}
+		return _parse.call(this, ctx);
+
+	}
+	return str.transform(async (imagePath, ctx) => {
+		const {
+			settings,
+			pluginContext,
+			filePath: entryFilePath
+		} = astroContext;
+		const resolvedFilePath = (await pluginContext.resolve(imagePath, entryFilePath))?.id;
+		const metadata = await emitESMImage(
+			resolvedFilePath,
+			pluginContext.meta.watchMode,
+			pluginContext.emitFile,
+			settings
+		);
+
+		if (!metadata) {
+			ctx.addIssue({
+				code: 'custom',
+				message: `Image ${imagePath} does not exist. Is the path correct?`,
+				fatal: true,
+			});
+
+			return z.NEVER;
+		}
+
+		return metadata;
+	});
+}

packages/astro/src/content/utils.ts

@@ -83,6 +83,16 @@ export async function getEntryData(
 			: collectionConfig.schema;
 
 	if (schema) {
+		// Override _processInputParams so we can pass down our own context.
+		const _processInputParams = schema._processInputParams;
+		schema._processInputParams = function(input: any) {
+			const out = _processInputParams.call(this, input);
+			out.ctx.astro = {
+				settings, pluginContext,
+				filePath: entry._internal.filePath
+			};
+			return out;
+		};
 		// Catch reserved `slug` field inside schema
 		// Note: will not warn for `z.union` or `z.intersection` schemas
 		if (typeof schema === 'object' && 'shape' in schema && schema.shape.slug) {