feat: support the post alias for short links.

src/content/config.ts

@@ -64,6 +64,7 @@ const postsCollection = defineCollection({
     date: z.date(),
     updated: z.date().optional(),
     comments: z.boolean().optional().default(true),
+    alias: z.array(z.string()).optional().default([]),
     tags: z.array(z.string()).optional().default([]),
     category: z.string(),
     summary: z.string().optional().default(''),

src/content/posts/2024/2024-09-04-third-bloom-in-sex.mdx

@@ -1,6 +1,10 @@
 ---
 title: 梅开三度 - 莲动妙处
 slug: third-bloom-in-sex
+alias:
+  - pa-pa-pa
+  - pia-pia-pia
+  - papapa
 date: 2024-09-04 15:42:12
 updated: 2024-09-04 15:50:12
 tags:

src/helpers/schema.ts

@@ -94,13 +94,21 @@ if (!options.isProd() && missingCovers.length > 0) {
   console.warn(missingCovers);
 }
 
-// Validate the posts and pages' slug. They should be unique globally.
+// Validate the posts and pages' slug and alias. They should be unique globally.
 const postsSlugs = new Set<string>();
 for (const post of posts) {
   if (postsSlugs.has(post.slug)) {
     throw new Error(`Duplicate post slug: ${post.slug}`);
   }
   postsSlugs.add(post.slug);
+
+  for (const alias of post.alias) {
+    if (postsSlugs.has(alias)) {
+      throw new Error(`Duplicate alias ${alias} in post ${post.slug}`);
+    }
+
+    postsSlugs.add(alias);
+  }
 }
 for (const page of pages) {
   if (postsSlugs.has(page.slug)) {

src/middleware.ts

@@ -2,7 +2,21 @@ import { posts } from '@/helpers/schema';
 import { urlJoin } from '@/helpers/tools';
 import { defineMiddleware } from 'astro:middleware';
 
-const mappings = new Map<string, string>(posts.map((post) => [urlJoin('/', post.slug), post.permalink]));
+const mappings = new Map<string, string>();
+
+const rewrites = posts.map((post) => ({
+  sources: [
+    urlJoin('/', post.slug),
+    ...post.alias.flatMap((alias) => [urlJoin('/', alias), urlJoin('/posts/', alias)]),
+  ],
+  target: post.permalink,
+}));
+
+for (const rewrite of rewrites) {
+  for (const source of rewrite.sources) {
+    mappings.set(source, rewrite.target);
+  }
+}
 
 export const onRequest = defineMiddleware(({ request: { method }, url: { pathname }, redirect }, next) => {
   // This is used for redirect my old blog posts to a new mapping.