generateImageMetadata
You can use generateImageMetadata
to generate different versions of one image or return multiple images for one route segment. This is useful for when you want to avoid hard-coding metadata values, such as for icons.
Parameters
generateImageMetadata
function accepts the following parameters:
params
(optional)
An object containing the dynamic route parameters object from the root segment down to the segment generateImageMetadata
is called from.
export function generateImageMetadata({
params,
}: {
params: { slug: string }
}) {
// ...
}
Route | URL | params |
---|---|---|
app/shop/icon.js | /shop | undefined |
app/shop/[slug]/icon.js | /shop/1 | { slug: '1' } |
app/shop/[tag]/[item]/icon.js | /shop/1/2 | { tag: '1', item: '2' } |
app/shop/[...slug]/icon.js | /shop/1/2 | { slug: ['1', '2'] } |
Returns
The generateImageMetadata
function should return an array
of objects containing the image's metadata such as alt
and size
. In addition, each item must include an id
value which will be passed to the props of the image generating function.
Image Metadata Object | Type |
---|---|
id | string (required) |
alt | string |
size | { width: number; height: number } |
contentType | string |
import { ImageResponse } from 'next/og'
export function generateImageMetadata() {
return [
{
contentType: 'image/png',
size: { width: 48, height: 48 },
id: 'small',
},
{
contentType: 'image/png',
size: { width: 72, height: 72 },
id: 'medium',
},
]
}
export default function Icon({ id }: { id: string }) {
return new ImageResponse(
(
<div
style={{
width: '100%',
height: '100%',
display: 'flex',
alignItems: 'center',
justifyContent: 'center',
fontSize: 88,
background: '#000',
color: '#fafafa',
}}
>
Icon {id}
</div>
)
)
}
Examples
Using external data
This example uses the params
object and external data to generate multiple Open Graph images for a route segment.
import { ImageResponse } from 'next/og'
import { getCaptionForImage, getOGImages } from '@/app/utils/images'
export async function generateImageMetadata({
params,
}: {
params: { id: string }
}) {
const images = await getOGImages(params.id)
return images.map((image, idx) => ({
id: idx,
size: { width: 1200, height: 600 },
alt: image.text,
contentType: 'image/png',
}))
}
export default async function Image({
params,
id,
}: {
params: { id: string }
id: number
}) {
const productId = params.id
const imageId = id
const text = await getCaptionForImage(productId, imageId)
return new ImageResponse(
(
<div
style={
{
// ...
}
}
>
{text}
</div>
)
)
}
Version History
Version | Changes |
---|---|
v13.3.0 | generateImageMetadata introduced. |
Next Steps
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