Next.js: Add metadata

Add static metadata

Export a metadata object from a layout or page file:

import type { Metadata } from 'next'
 
export const metadata: Metadata = {
  title: 'My Blog',
  description: '...',
}
 
export default function Page() {}

Add dynamic metadata

import type { Metadata, ResolvingMetadata } from 'next'
 
type Props = {
  params: Promise<{ slug: string }>
  searchParams: Promise<{ [key: string]: string | string[] | undefined }>
}
 
export async function generateMetadata(
  { params, searchParams }: Props,
  parent: ResolvingMetadata
): Promise<Metadata> {
  const slug = (await params).slug
 
  // fetch post information
  const post = await fetch(`https://api.vercel.app/blog/${slug}`).then((res) =>
    res.json()
  )
 
  return {
    title: post.title,
    description: post.description,
  }
}
 
export default function Page({ params, searchParams }: Props) {}

If your generateMetadata function fetches the same data as the page or layout, you might want to use React’s cache function to deduplicate the requests:

import { cache } from 'react'
import { db } from '@/app/lib/db'
 
// getPost will be used twice, but execute only once
export const getPost = cache(async (slug: string) => {
  const res = await db.query.posts.findFirst({ where: eq(posts.slug, slug) })
  return res
})

Then, in your generateMetadata function and page component:

import { getPost } from '@/app/lib/data'
 
export async function generateMetadata({
  params,
}: {
  params: { slug: string }
}) {
  const post = await getPost(params.slug)
  return {
    title: post.title,
    description: post.description,
  }
}
 
export default async function Page({ params }: { params: { slug: string } }) {
  const post = await getPost(params.slug)
  return <div>{post.title}</div>
}