fix(runtime): check head+content component before throwing an error (#11141)

* fix(runtime): check head+content component before throwing an error

* add test

.changeset/silver-bananas-move.md

@@ -0,0 +1,13 @@
+---
+"astro": patch
+---
+
+Fixes an internal error that prevented the `AstroContainer` to render the `Content` component.
+
+You can now write code similar to the following to render content collections:
+
+```js
+const entry = await getEntry(collection, slug);
+const { Content } = await entry.render();
+const content = await container.renderToString(Content);
+```

packages/astro/src/runtime/server/render/astro/render.ts

@@ -148,6 +148,25 @@ async function callComponentAsTemplateResultOrResponse(
 
 	if (factoryResult instanceof Response) {
 		return factoryResult;
+	} 
+	// we check if the component we attempt to render is a head+content
+	else if (isHeadAndContent(factoryResult)) {
+		// we make sure that content is valid template result
+		if (!isRenderTemplateResult(factoryResult.content)) {
+			throw new AstroError({
+				...AstroErrorData.OnlyResponseCanBeReturned,
+				message: AstroErrorData.OnlyResponseCanBeReturned.message(
+					route?.route,
+					typeof factoryResult
+				),
+				location: {
+					file: route?.component,
+				},
+			});
+		}
+
+		// return the content
+		return factoryResult.content;
 	} else if (!isRenderTemplateResult(factoryResult)) {
 		throw new AstroError({
 			...AstroErrorData.OnlyResponseCanBeReturned,
@@ -158,7 +177,7 @@ async function callComponentAsTemplateResultOrResponse(
 		});
 	}
 
-	return isHeadAndContent(factoryResult) ? factoryResult.content : factoryResult;
+	return factoryResult;
 }
 
 // Recursively calls component instances that might have head content

packages/astro/test/container.test.js

@@ -9,6 +9,8 @@ import {
 	renderComponent,
 	renderHead,
 	renderSlot,
+	createHeadAndContent,
+	renderTemplate
 } from '../dist/runtime/server/index.js';
 
 const BaseLayout = createComponent((result, _props, slots) => {
@@ -140,6 +142,54 @@ describe('Container', () => {
 		assert.match(result, /Bar name/);
 	});
 
+	it('Renders content and head component', async () => {
+		const Page = createComponent(
+			(result, _props, slots) => {
+
+				return createHeadAndContent(
+					'',
+					renderTemplate`${renderComponent(
+						result,
+						'BaseLayout',
+						BaseLayout,
+						{},
+						{
+							default: () => render`
+							${maybeRenderHead(result)}
+							${renderSlot(result, slots['custom-name'])}
+							${renderSlot(result, slots['foo-name'])}
+							`,
+							head: () => render`
+						${renderComponent(
+								result,
+								'Fragment',
+								Fragment,
+								{ slot: 'head' },
+								{
+									default: () => render`<meta charset="utf-8">`,
+								}
+							)}
+					`,
+						}
+					)}`
+			);
+			},
+			'Component2.astro',
+			undefined
+		);
+
+		const container = await experimental_AstroContainer.create();
+		const result = await container.renderToString(Page, {
+			slots: {
+				'custom-name': 'Custom name',
+				'foo-name': 'Bar name',
+			},
+		});
+
+		assert.match(result, /Custom name/);
+		assert.match(result, /Bar name/);
+	});
+
 	it('Renders props', async () => {
 		const Page = createComponent(
 			(result, props, _slots) => {