feat(router): add ability to provide meta tags

apps/blog-app/src/app/blog/models.ts

@@ -0,0 +1,6 @@
+export interface PostAttributes {
+  title: string;
+  slug: string;
+  description: string;
+  coverImage: string;
+}

apps/blog-app/src/app/blog/resolvers.ts

@@ -0,0 +1,44 @@
+import { ActivatedRouteSnapshot, ResolveFn } from '@angular/router';
+import { MetaTag } from '@analogjs/router';
+import { injectContentFiles } from '@analogjs/content';
+import { PostAttributes } from './models';
+
+// temporary
+function injectActivePostAttributes(
+  route: ActivatedRouteSnapshot
+): PostAttributes {
+  return injectContentFiles<PostAttributes>().find(
+    (contentFile) =>
+      contentFile.filename === `/src/content/${route.params['slug']}.md`
+  )!.attributes;
+}
+
+export const postTitleResolver: ResolveFn<string> = (route) =>
+  injectActivePostAttributes(route).title;
+
+export const postMetaResolver: ResolveFn<MetaTag[]> = (route) => {
+  const postAttributes = injectActivePostAttributes(route);
+
+  return [
+    {
+      name: 'description',
+      content: postAttributes.description,
+    },
+    {
+      name: 'author',
+      content: 'Analog Team',
+    },
+    {
+      property: 'og:title',
+      content: postAttributes.title,
+    },
+    {
+      property: 'og:description',
+      content: postAttributes.description,
+    },
+    {
+      property: 'og:image',
+      content: postAttributes.coverImage,
+    },
+  ];
+};

apps/blog-app/src/app/routes/blog.ts

@@ -2,26 +2,26 @@ import { Component } from '@angular/core';
 import { RouterLink, RouterOutlet } from '@angular/router';
 import { injectContentFiles } from '@analogjs/content';
 import { NgFor } from '@angular/common';
+import { RouteMeta } from '@analogjs/router';
+import { PostAttributes } from '../blog/models';
+
+export const routeMeta: RouteMeta = {
+  title: 'Analog Blog',
+  meta: [{ name: 'description', content: 'Analog Blog Posts' }],
+};
 
-interface MyAttributes {
-  title: string;
-  slug: string;
-}
 @Component({
-  selector: 'blog',
   standalone: true,
   imports: [RouterOutlet, RouterLink, NgFor],
   template: `
-    <ng-container *ngFor="let attribute of fileAttributes">
-      <a [routerLink]="attribute.slug"> {{ attribute.title }}</a> |
+    <ng-container *ngFor="let post of posts">
+      <a [routerLink]="post.attributes.slug"> {{ post.attributes.title }}</a> |
     </ng-container>
     <a routerLink="/about">About</a>
 
     <router-outlet></router-outlet>
   `,
 })
 export default class BlogComponent {
-  public fileAttributes = injectContentFiles<MyAttributes>().map(
-    (file) => file.attributes
-  );
+  readonly posts = injectContentFiles<PostAttributes>();
 }

apps/blog-app/src/app/routes/blog/[slug].ts

@@ -1,19 +1,25 @@
 import { injectContent, MarkdownComponent } from '@analogjs/content';
 import { AsyncPipe, NgIf } from '@angular/common';
 import { Component } from '@angular/core';
-import { BlogAttributes } from '../../../lib/blog-attributes';
+import { RouteMeta } from '@analogjs/router';
+import { PostAttributes } from '../../blog/models';
+import { postMetaResolver, postTitleResolver } from '../../blog/resolvers';
+
+export const routeMeta: RouteMeta = {
+  title: postTitleResolver,
+  meta: postMetaResolver,
+};
 
 @Component({
-  selector: 'blog-post',
   standalone: true,
   imports: [MarkdownComponent, AsyncPipe, NgIf],
   template: `
-    <ng-container *ngIf="contentFile$ | async as cf">
-      <h1>{{ cf.attributes.title }}</h1>
-      <analog-markdown [content]="cf.content"></analog-markdown>
+    <ng-container *ngIf="post$ | async as post">
+      <h1>{{ post.attributes.title }}</h1>
+      <analog-markdown [content]="post.content"></analog-markdown>
     </ng-container>
   `,
 })
 export default class BlogPostComponent {
-  public contentFile$ = injectContent<BlogAttributes>();
+  readonly post$ = injectContent<PostAttributes>();
 }

apps/blog-app/src/content/2022-12-27-my-first-post.md

@@ -1,6 +1,8 @@
 ---
 title: My First Post
 slug: 2022-12-27-my-first-post
+description: My First Post Description
+coverImage: https://images.unsplash.com/photo-1493612276216-ee3925520721?ixlib=rb-4.0.3&ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&auto=format&fit=crop&w=464&q=80
 ---
 
 Hello

apps/blog-app/src/content/2022-12-31-my-second-post.md

@@ -1,6 +1,8 @@
 ---
 title: My Second Post
 slug: 2022-12-31-my-second-post
+description: My Second Post Description
+coverImage: https://images.unsplash.com/photo-1481627834876-b7833e8f5570?ixlib=rb-4.0.3&ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&auto=format&fit=crop&w=928&q=80
 ---
 
 - [Home](/)

packages/router/src/index.ts

@@ -5,4 +5,5 @@ export {
   injectRouter,
 } from './lib/define-route';
 export { RouteMeta } from './lib/models';
-export { provideFileRouter } from './lib/provide-file-routes';
+export { provideFileRouter } from './lib/provide-file-router';
+export { MetaTag } from './lib/meta-tags';

packages/router/src/lib/meta-tags.spec.ts

@@ -0,0 +1,227 @@
+import { Component, ENVIRONMENT_INITIALIZER } from '@angular/core';
+import { Route, Router, RouterOutlet } from '@angular/router';
+import { fakeAsync, TestBed, tick } from '@angular/core/testing';
+import { RouterTestingModule } from '@angular/router/testing';
+import { map, timer } from 'rxjs';
+import {
+  MetaTag,
+  ROUTE_META_TAGS_KEY,
+  setMetaTagsOnRouteChange,
+} from './meta-tags';
+import { DOCUMENT } from '@angular/common';
+import { expect } from 'vitest';
+
+describe('setMetaTagsOnRouteChange', () => {
+  function setup() {
+    @Component({
+      standalone: true,
+      imports: [RouterOutlet],
+      template: '<router-outlet></router-outlet>',
+    })
+    class TestComponent {}
+
+    const parentMetaTagValues = {
+      charset: 'utf-8',
+      httpEquivRefresh: '1000',
+      description: 'Parent Description',
+      keywords: 'Analog, Angular',
+      ogTitle: 'Parent Og:Title',
+      ogImage: 'https://example.com',
+    };
+
+    const childMetaTagValues = {
+      charset: 'ascii',
+      httpEquivRefresh: '3000',
+      httpEquivContentSec: "default-src 'self'",
+      description: 'Child Description',
+      author: 'Analog Team',
+      ogTitle: 'Child Og:Title',
+      ogDescription: 'Child Og:Description',
+    };
+
+    const routes: Route[] = [
+      {
+        path: '',
+        component: TestComponent,
+        data: {
+          [ROUTE_META_TAGS_KEY]: [
+            { charset: parentMetaTagValues.charset },
+            {
+              httpEquiv: 'refresh',
+              content: parentMetaTagValues.httpEquivRefresh,
+            },
+            { name: 'description', content: parentMetaTagValues.description },
+            { name: 'keywords', content: parentMetaTagValues.keywords },
+            { property: 'og:title', content: parentMetaTagValues.ogTitle },
+            { property: 'og:image', content: parentMetaTagValues.ogImage },
+          ] as MetaTag[],
+        },
+        children: [
+          {
+            path: 'child',
+            component: TestComponent,
+            resolve: {
+              [ROUTE_META_TAGS_KEY]: () =>
+                timer(1000).pipe(
+                  map(
+                    () =>
+                      [
+                        { charset: childMetaTagValues.charset },
+                        {
+                          httpEquiv: 'refresh',
+                          content: childMetaTagValues.httpEquivRefresh,
+                        },
+                        {
+                          httpEquiv: 'content-security-policy',
+                          content: childMetaTagValues.httpEquivContentSec,
+                        },
+                        {
+                          name: 'description',
+                          content: childMetaTagValues.description,
+                        },
+                        { name: 'author', content: childMetaTagValues.author },
+                        {
+                          property: 'og:title',
+                          content: childMetaTagValues.ogTitle,
+                        },
+                        {
+                          property: 'og:description',
+                          content: childMetaTagValues.ogDescription,
+                        },
+                      ] as MetaTag[]
+                  )
+                ),
+            },
+          },
+        ],
+      },
+    ];
+
+    TestBed.configureTestingModule({
+      imports: [RouterTestingModule.withRoutes(routes)],
+      providers: [
+        {
+          provide: ENVIRONMENT_INITIALIZER,
+          multi: true,
+          useValue: () => setMetaTagsOnRouteChange(),
+        },
+      ],
+    });
+
+    const router = TestBed.inject(Router);
+    const document = TestBed.inject(DOCUMENT);
+
+    const getMetaElements = () => ({
+      charset: document.querySelector('meta[charset]') as HTMLMetaElement,
+      httpEquivRefresh: document.querySelector(
+        'meta[http-equiv="refresh"]'
+      ) as HTMLMetaElement,
+      httpEquivContentSec: document.querySelector(
+        'meta[http-equiv="content-security-policy"]'
+      ) as HTMLMetaElement,
+      description: document.querySelector(
+        'meta[name="description"]'
+      ) as HTMLMetaElement,
+      keywords: document.querySelector(
+        'meta[name="keywords"]'
+      ) as HTMLMetaElement,
+      author: document.querySelector('meta[name="author"]') as HTMLMetaElement,
+      ogTitle: document.querySelector(
+        'meta[property="og:title"]'
+      ) as HTMLMetaElement,
+      ogDescription: document.querySelector(
+        'meta[property="og:description"]'
+      ) as HTMLMetaElement,
+      ogImage: document.querySelector(
+        'meta[property="og:image"]'
+      ) as HTMLMetaElement,
+    });
+
+    return { router, getMetaElements, parentMetaTagValues, childMetaTagValues };
+  }
+
+  it('adds meta tags on initial navigation', fakeAsync(() => {
+    const { router, getMetaElements, parentMetaTagValues } = setup();
+
+    router.navigateByUrl('/');
+    tick();
+
+    const metaElements = getMetaElements();
+    expect(metaElements.charset.getAttribute('charset')).toBe(
+      parentMetaTagValues.charset
+    );
+    expect(metaElements.httpEquivRefresh.content).toBe(
+      parentMetaTagValues.httpEquivRefresh
+    );
+    expect(metaElements.description.content).toBe(
+      parentMetaTagValues.description
+    );
+    expect(metaElements.keywords.content).toBe(parentMetaTagValues.keywords);
+    expect(metaElements.ogTitle.content).toBe(parentMetaTagValues.ogTitle);
+    expect(metaElements.ogImage.content).toBe(parentMetaTagValues.ogImage);
+  }));
+
+  it('merges parent and child meta tags on child route navigation', fakeAsync(() => {
+    const { router, getMetaElements, parentMetaTagValues, childMetaTagValues } =
+      setup();
+
+    router.navigateByUrl('/child');
+    // child meta tags are resolved after 1s
+    tick(1000);
+
+    const metaElements = getMetaElements();
+    expect(metaElements.charset.getAttribute('charset')).toBe(
+      childMetaTagValues.charset
+    );
+    expect(metaElements.httpEquivRefresh.content).toBe(
+      childMetaTagValues.httpEquivRefresh
+    );
+    expect(metaElements.httpEquivContentSec.content).toBe(
+      childMetaTagValues.httpEquivContentSec
+    );
+    expect(metaElements.description.content).toBe(
+      childMetaTagValues.description
+    );
+    expect(metaElements.author.content).toBe(childMetaTagValues.author);
+    expect(metaElements.ogTitle.content).toBe(childMetaTagValues.ogTitle);
+    expect(metaElements.ogDescription.content).toBe(
+      childMetaTagValues.ogDescription
+    );
+    // meta tags inherited from parent route
+    expect(metaElements.keywords.content).toBe(parentMetaTagValues.keywords);
+    expect(metaElements.ogImage.content).toBe(parentMetaTagValues.ogImage);
+  }));
+
+  it('lefts over meta tags from the previous route that are not changed', fakeAsync(() => {
+    const { router, getMetaElements, parentMetaTagValues, childMetaTagValues } =
+      setup();
+
+    router.navigateByUrl('/child');
+    tick(1000);
+
+    router.navigateByUrl('/');
+    tick();
+
+    const metaElements = getMetaElements();
+    expect(metaElements.charset.getAttribute('charset')).toBe(
+      parentMetaTagValues.charset
+    );
+    expect(metaElements.description.content).toBe(
+      parentMetaTagValues.description
+    );
+    expect(metaElements.keywords.content).toBe(parentMetaTagValues.keywords);
+    expect(metaElements.httpEquivRefresh.content).toBe(
+      parentMetaTagValues.httpEquivRefresh
+    );
+    expect(metaElements.ogTitle.content).toBe(parentMetaTagValues.ogTitle);
+    expect(metaElements.ogImage.content).toBe(parentMetaTagValues.ogImage);
+    // meta tags that are not changed
+    expect(metaElements.httpEquivContentSec.content).toBe(
+      childMetaTagValues.httpEquivContentSec
+    );
+    expect(metaElements.author.content).toBe(childMetaTagValues.author);
+    expect(metaElements.ogDescription.content).toBe(
+      childMetaTagValues.ogDescription
+    );
+  }));
+});