Takes a JSON specification and outputs a production-ready Next.js application with routes, layouts, server-side rendering, and metadata—no manual scaffolding required.
Best for: Engineers building multi-page apps from AI-generated specs or JSON templates.
Creator's repository · vercel-labs/json-render
License: Apache-2.0
---
name: next
description: Next.js renderer for json-render that turns JSON specs into full Next.js applications with routes, layouts, SSR, and metadata. Use when working with @json-render/next, building Next.js apps from JSON specs, or creating AI-generated multi-page applications.
---
# @json-render/next
Next.js renderer that converts JSON specs into full Next.js applications with routes, pages, layouts, metadata, and SSR support.
## Quick Start
```bash
npm install @json-render/core @json-render/react @json-render/next
```
### 1. Define Your Spec
```typescript
// lib/spec.ts
import type { NextAppSpec } from "@json-render/next";
export const spec: NextAppSpec = {
metadata: {
title: { default: "My App", template: "%s | My App" },
description: "A json-render Next.js application",
},
layouts: {
main: {
root: "shell",
elements: {
shell: { type: "Container", props: {}, children: ["nav", "slot"] },
nav: { type: "NavBar", props: { links: [
{ href: "/", label: "Home" },
{ href: "/about", label: "About" },
]}, children: [] },
slot: { type: "Slot", props: {}, children: [] },
},
},
},
routes: {
"/": {
layout: "main",
metadata: { title: "Home" },
page: {
root: "hero",
elements: {
hero: { type: "Card", props: { title: "Welcome" }, children: [] },
},
},
},
"/about": {
layout: "main",
metadata: { title: "About" },
page: {
root: "content",
elements: {
content: { type: "Card", props: { title: "About Us" }, children: [] },
},
},
},
},
};
```
### 2. Create the App
```typescript
// lib/app.ts
import { createNextApp } from "@json-render/next/server";
import { spec } from "./spec";
export const { Page, generateMetadata, generateStaticParams } = createNextApp({
spec,
loaders: {
// Server-side data loaders (optional)
loadPost: async ({ slug }) => {
const post = await getPost(slug as string);
return { post };
},
},
});
```
### 3. Wire Up Route Files
```tsx
// app/[[...slug]]/page.tsx
export { Page as default, generateMetadata, generateStaticParams } from "@/lib/app";
```
```tsx
// app/[[...slug]]/layout.tsx
import { NextAppProvider } from "@json-render/next";
import { registry, handlers } from "@/lib/registry";
export default function Layout({ children }: { children: React.ReactNode }) {
return (
<html lang="en">
<body>
<NextAppProvider registry={registry} handlers={handlers}>
{children}
</NextAppProvider>
</body>
</html>
);
}
```
## Key Concepts
### NextAppSpec
The top-level spec defines an entire Next.js application:
- **metadata**: Root-level SEO metadata (title template, description, OpenGraph)
- **layouts**: Reusable layout element trees (each must include a `Slot` component)
- **routes**: Route definitions keyed by URL pattern
- **state**: Global initial state shared across all routes
### Route Patterns
Routes use Next.js URL conventions:
- `"/"` -- home page
- `"/about"` -- static route
- `"/blog/[slug]"` -- dynamic segment
- `"/docs/[...path]"` -- catch-all segment
- `"/settings/[[...path]]"` -- optional catch-all segment
### Layouts
Layouts wrap page content. Every layout MUST include a `Slot` component where page content will be rendered. Layouts are defined once in `spec.layouts` and referenced by routes via the `layout` field.
### Built-in Components
- **Slot**: Placeholder in layouts where page content is rendered
- **Link**: Client-side navigation link (wraps `next/link`)
### Built-in Actions
- **setState**: Update state value. Params: `{ statePath, value }`
- **pushState**: Append to array. Params: `{ statePath, value, clearStatePath? }`
- **removeState**: Remove from array by index. Params: `{ statePath, index }`
- **navigate**: Client-side navigation. Params: `{ href }`
### Data Loaders
Server-side async functions that run in the Server Component before rendering. Results are merged into the page's initial state.
```typescript
createNextApp({
spec,
loaders: {
loadPost: async ({ slug }) => {
const post = await db.post.findUnique({ where: { slug } });
return { post };
},
},
});
```
### SSR
Pages are server-rendered automatically. The `createNextApp` `Page` component is an async Server Component that:
1. Matches the route from the spec
2. Runs server-side data loaders
3. Generates metadata
4. Passes the resolved spec to the client renderer for hydration
### Entry Points
- `@json-render/next` -- Client components (NextAppProvider, PageRenderer, Link)
- `@json-render/next/server` -- Server utilities (createNextApp, matchRoute, schema)
## API Reference
### Server Exports (`@json-render/next/server`)
- `createNextApp(options)` -- Create Page, generateMetadata, generateStaticParams
- `schema` -- Custom schema for Next.js apps (for AI catalog generation)
- `matchRoute(spec, pathname)` -- Match a URL to a route spec
- `resolveMetadata(spec, route)` -- Resolve metadata for a route
- `slugToPath(slug)` -- Convert catch-all slug array to pathname
- `collectStaticParams(spec)` -- Collect static params for all routes
### Client Exports (`@json-render/next`)
- `NextAppProvider` -- Context provider for registry and handlers
- `PageRenderer` -- Renders a page spec with optional layout
- `NextErrorBoundary` -- Error boundary component
- `NextLoading` -- Loading state component
- `NextNotFound` -- Not-found component
- `Link` -- Built-in navigation component (wraps next/link)