Content Collections

Status: Production Ready ✅ Last Updated: 2025-11-07 Dependencies: None Latest Versions: @content-collections/core@0.12.0, @content-collections/vite@0.2.7, zod@3.23.8

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What is Content Collections?

Content Collections transforms local content files (Markdown/MDX) into type-safe TypeScript data with automatic validation at build time.

Problem it solves: Manual content parsing, lack of type safety, runtime errors from invalid frontmatter.

How it works:

1. Define collections in content-collections.ts (name, directory, Zod schema)
2. CLI/plugin scans filesystem, parses frontmatter, validates against schema
3. Generates TypeScript modules in .content-collections/generated/
4. Import collections: import { allPosts } from "content-collections"

Perfect for: Blogs, documentation sites, content-heavy apps with Cloudflare Workers, Vite, Next.js.

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Quick Start (5 Minutes)

1. Install Dependencies

# Bun (recommended)
bun add -d @content-collections/core @content-collections/vite zod

# npm
npm install -D @content-collections/core @content-collections/vite zod

# pnpm
pnpm add -D @content-collections/core @content-collections/vite zod

2. Configure TypeScript Path Alias

Add to tsconfig.json:

{
  "compilerOptions": {
    "paths": {
      "content-collections": ["./.content-collections/generated"]
    }
  }
}

3. Configure Vite Plugin

Add to vite.config.ts:

import { defineConfig } from "vite";
import react from "@vitejs/plugin-react";
import contentCollections from "@content-collections/vite";

export default defineConfig({
  plugins: [
    react(),
    contentCollections(), // MUST come after react()
  ],
});

4. Update .gitignore

.content-collections/

5. Create Collection Config

Create content-collections.ts in project root:

import { defineCollection, defineConfig } from "@content-collections/core";
import { z } from "zod";

const posts = defineCollection({
  name: "posts",
  directory: "content/posts",
  include: "*.md",
  schema: z.object({
    title: z.string(),
    date: z.string(),
    description: z.string(),
    content: z.string(),
  }),
});

export default defineConfig({
  collections: [posts],
});

6. Create Content Directory

mkdir -p content/posts

Create content/posts/first-post.md:

---
title: My First Post
date: 2025-11-07
description: Introduction to Content Collections
---

# My First Post

Content goes here...

7. Import and Use

import { allPosts } from "content-collections";

console.log(allPosts); // Fully typed!

Result: Type-safe content with autocomplete, validation, and HMR.

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Critical Rules

✅ Always Do:

1. Add path alias to tsconfig.json - Required for imports to work
2. Add .content-collections to .gitignore - Generated files shouldn't be committed
3. Use Standard Schema validators - Zod, Valibot, ArkType supported
4. Include content field in schema - Required for frontmatter parsing
5. Await compileMDX in transforms - MDX compilation is async
6. Put contentCollections() after react() in Vite - Plugin order matters

❌ Never Do:

1. Commit .content-collections directory - Always generated, never committed
2. Use non-standard validators - Must support StandardSchema spec
3. Forget to restart dev server after config changes - Required for new collections
4. Use sync transforms with async operations - Transform must be async
5. Double-wrap path alias - Use content-collections not ./content-collections
6. Import from wrong package - @content-collections/core for config, content-collections for data

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Known Issues Prevention

Issue #1: Module not found: 'content-collections'

Error: Cannot find module 'content-collections' or its corresponding type declarations

Why it happens: Missing TypeScript path alias configuration.

Prevention:

Add to tsconfig.json:

{
  "compilerOptions": {
    "paths": {
      "content-collections": ["./.content-collections/generated"]
    }
  }
}

Restart TypeScript server in VS Code: Cmd+Shift+P → "TypeScript: Restart TS Server"

Source: Common user error

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Issue #2: Vite Constant Restart Loop

Error: Dev server continuously restarts, infinite loop.

Why it happens: Vite watching .content-collections directory changes, which triggers regeneration.

Prevention:

1. Add to .gitignore:

.content-collections/

2. Add to vite.config.ts (if still happening):

export default defineConfig({
  server: {
    watch: {
      ignored: ["**/.content-collections/**"],
    },
  },
});

Source: GitHub Issue #591 (TanStack Start)

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Issue #3: Transform Types Not Reflected

Error: TypeScript types don't match transformed documents.

Why it happens: TypeScript doesn't automatically infer transform function return type.

Prevention:

Explicitly type your transform return:

const posts = defineCollection({
  name: "posts",
  // ... schema
  transform: (post): PostWithSlug => ({ // Type the return!
    ...post,
    slug: post._meta.path.replace(/\.md$/, ""),
  }),
});

type PostWithSlug = {
  // ... schema fields
  slug: string;
};

Source: GitHub Issue #396

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Issues #4-8: Advanced Troubleshooting

Additional issues covered in references/advanced-troubleshooting.md:

Issue	Error	Quick Fix
#4	Collection not updating	Verify glob pattern, restart dev server
#5	MDX/Shiki errors	Use compatible versions (shiki ^1.0.0)
#6	MDX path aliases fail	Use relative paths in MDX imports
#7	Unclear validation errors	Add custom Zod error messages
#8	Ctrl+C doesn't stop	Use kill -9 or separate watch command

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Configuration Patterns

Pattern	Use Case	Template
Basic Blog	Single collection, Markdown only	templates/content-collections.ts
Multi-Collection	Posts + Docs, nested folders	templates/content-collections-multi.ts
Transform Functions	Computed fields (slug, readingTime)	See references/transform-cookbook.md
MDX + React	Syntax highlighting, React components	templates/content-collections-mdx.ts

For detailed schema patterns (dates, tags, validation), load references/schema-patterns.md.

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React Component Integration

Using Collections in React

import { allPosts } from "content-collections";

export function BlogList() {
  return (
    <ul>
      {allPosts.map((post) => (
        <li key={post._meta.path}>
          <h2>{post.title}</h2>
          <p>{post.description}</p>
          <time>{post.date}</time>
        </li>
      ))}
    </ul>
  );
}

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Rendering MDX Content

import { MDXContent } from "@content-collections/mdx/react";

export function BlogPost({ post }: { post: { mdx: string } }) {
  return (
    <article>
      <MDXContent code={post.mdx} />
    </article>
  );
}

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Cloudflare Workers Deployment

Content Collections is perfect for Cloudflare Workers (build-time only, no runtime filesystem). Use template templates/wrangler.toml for config.

Pattern: vite build → wrangler deploy (Vite plugin handles content-collections automatically)

For detailed deployment guide, load references/deployment-guide.md.

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Bundled Resources

Templates (9 copy-paste files)

content-collections.ts, content-collections-multi.ts, content-collections-mdx.ts, tsconfig.json, vite.config.ts, BlogList.tsx, BlogPost.tsx, blog-post.md, wrangler.toml

Scripts

init-content-collections.sh - One-command automated setup

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Dependencies

Required

{
  "devDependencies": {
    "@content-collections/core": "^0.12.0",
    "@content-collections/vite": "^0.2.7",
    "zod": "^3.23.8"
  }
}

Optional (MDX)

{
  "devDependencies": {
    "@content-collections/markdown": "^0.1.4",
    "@content-collections/mdx": "^0.2.2",
    "shiki": "^1.0.0"
  }
}

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Official Documentation

• Official Site: https://www.content-collections.dev
• Documentation: https://www.content-collections.dev/docs
• GitHub: https://github.com/sdorra/content-collections
• Vite Plugin: https://www.content-collections.dev/docs/vite
• MDX Integration: https://www.content-collections.dev/docs/mdx

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Package Versions (Verified 2025-11-07)

Package	Version	Status
@content-collections/core	0.12.0	✅ Latest stable
@content-collections/vite	0.2.7	✅ Latest stable
@content-collections/mdx	0.2.2	✅ Latest stable
@content-collections/markdown	0.1.4	✅ Latest stable
zod	3.23.8	✅ Latest stable

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Quick Troubleshooting

Problem	Solution
TypeScript can't find module	Add path alias to tsconfig.json, restart TS server
Vite keeps restarting	Add .content-collections/ to .gitignore
Changes not reflecting	Restart dev server, verify glob pattern
MDX compilation errors	Check Shiki version compatibility
Validation errors unclear	Add custom Zod error messages

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When to Load References

Reference	Load When...
schema-patterns.md	Setting up complex schemas, date validation, optional fields
transform-cookbook.md	Adding computed fields, async transforms, slugs
mdx-components.md	Integrating React components in MDX, syntax highlighting
deployment-guide.md	Deploying to Cloudflare Workers or other platforms
advanced-troubleshooting.md	Issues #4-8 (file watching, path aliases, process hanging)

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Complete Setup Checklist

• Installed @content-collections/core and @content-collections/vite
• Installed zod for schema validation
• Added path alias to tsconfig.json
• Added contentCollections() to vite.config.ts (after react())
• Added .content-collections/ to .gitignore
• Created content-collections.ts in project root
• Created content directory (e.g., content/posts/)
• Defined collection with Zod schema
• Created first content file with frontmatter
• Imported collection in React component
• Verified types work (autocomplete)
• Tested hot reloading (change content file)