@prismicio/next/src/pages/redirectToPreviewURL.ts

Helpers to integrate Prismic into Next.js apps

import type { LinkResolverFunction, Client } from "@prismicio/client"

import type { NextApiRequestLike, NextApiResponseLike } from "./types"

export type RedirectToPreviewURLConfig = {
	/** The Prismic client configured for the preview session's repository. */
	// `Pick` is used to use the smallest possible subset of
	// `prismic.Client`. Doing this reduces the surface area for breaking
	// type changes.
	client: Pick<Client, "resolvePreviewURL">

	/**
	 * The `req` object from a Next.js API route.
	 *
	 * @see Next.js API route docs: \<https://nextjs.org/docs/pages/building-your-application/routing/api-routes\>
	 */
	req: NextApiRequestLike

	/**
	 * The `res` object from a Next.js API route.
	 *
	 * @see Next.js API route docs: \<https://nextjs.org/docs/pages/building-your-application/routing/api-routes\>
	 */
	res: NextApiResponseLike

	/**
	 * A Link Resolver used to resolve the previewed document's URL.
	 *
	 * @see To learn more about Link Resolver: {@link https://prismic.io/docs/core-concepts/link-resolver-route-resolver}
	 */
	linkResolver?: LinkResolverFunction

	/**
	 * The default redirect URL if a URL cannot be determined for the previewed document.
	 *
	 * **Note**: If you `next.config.js` file contains a `basePath`, the `defaultURL` option must
	 * _not_ include it. Instead, provide the `basePath` property using the `basePath` option.
	 */
	defaultURL?: string

	/**
	 * The `basePath` for the Next.js app as it is defined in `next.config.js`. This option can be
	 * omitted if the app does not have a `basePath`.
	 *
	 * @remarks
	 *   The Router Handler or API route is unable to detect the app's `basePath` automatically. It
	 *   must be provided to `redirectToPreviewURL()` manually.
	 */
	basePath?: string
}

export async function redirectToPreviewURL(config: RedirectToPreviewURLConfig): Promise<void> {
	const { client, req, res, linkResolver, defaultURL = "/", basePath = "" } = config

	const previewToken = req.query.token?.toString()

	const previewURL = await client.resolvePreviewURL({
		linkResolver,
		defaultURL,
		previewToken,
	})

	res.redirect(basePath + previewURL)

	return
}