From 26c80eeb16bb4f47784b168cb25fb0095a2d1259 Mon Sep 17 00:00:00 2001
From: Ian Marlier <marlier@gmail.com>
Date: Thu, 25 Jul 2024 16:37:13 -0400
Subject: [PATCH] GTM dataLayer parameter should take an object, not an array
 of strings (#66339)

<!-- Thanks for opening a PR! Your contribution is much appreciated.
To make sure your PR is handled as smoothly as possible we request that
you follow the checklist sections below.
Choose the right checklist for the change(s) that you're making:

## For Contributors

### Improving Documentation

- Run `pnpm prettier-fix` to fix formatting issues before opening the
PR.
- Read the Docs Contribution Guide to ensure your contribution follows
the docs guidelines:
https://nextjs.org/docs/community/contribution-guide

### Adding or Updating Examples

- The "examples guidelines" are followed from our contributing doc
https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md
- Make sure the linting passes by running `pnpm build && pnpm lint`. See
https://github.com/vercel/next.js/blob/canary/contributing/repository/linting.md

### Fixing a bug

- Related issues linked using `fixes #number`
- Tests added. See:
https://github.com/vercel/next.js/blob/canary/contributing/core/testing.md#writing-tests-for-nextjs
- Errors have a helpful link attached, see
https://github.com/vercel/next.js/blob/canary/contributing.md

### Adding a feature

- Implements an existing feature request or RFC. Make sure the feature
request has been accepted for implementation before opening a PR. (A
discussion must be opened, see
https://github.com/vercel/next.js/discussions/new?category=ideas)
- Related issues/discussions are linked using `fixes #number`
- e2e tests added
(https://github.com/vercel/next.js/blob/canary/contributing/core/testing.md#writing-tests-for-nextjs)
- Documentation added
- Telemetry added. In case of a feature if it's used or not.
- Errors have a helpful link attached, see
https://github.com/vercel/next.js/blob/canary/contributing.md

## For Maintainers

- Minimal description (aim for explaining to someone not on the team to
understand the PR)
- When linking to a Slack thread, you might want to share details of the
conclusion
- Link both the Linear (Fixes NEXT-xxx) and the GitHub issues
- Add review comments if necessary to explain to the reviewer the logic
behind a change

### What?

### Why?

### How?

Closes NEXT-
Fixes #

-->

fixes #64364

As noted in the bug, the `dataLayer` parameter to the GoogleTagManager
third-party component should be an object (which gets passed to
`JSON.stringify()` at
https://github.com/vercel/next.js/blob/canary/packages/third-parties/src/google/gtm.tsx#L43),
and not an array of strings.

(I'm speculating a bit, but assuming that the original intent was that
an object could be serialized and passed to the component, but then the
call to stringify was added to the component as well.)

I'm not thrilled about duplicating the JSONValue type, which also exists
in `packages/next/src/server/config-shared.ts`, but wasn't sure whether
it would be preferred to export from there -- this doesn't feel like
it's likely to be an issue, but I'm perfectly happy to change

---------

Co-authored-by: Sam Ko <sam@vercel.com>
---
 packages/third-parties/src/types/google.ts | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/packages/third-parties/src/types/google.ts b/packages/third-parties/src/types/google.ts
index 30a4e9f28a464..aaae926d2a5c6 100644
--- a/packages/third-parties/src/types/google.ts
+++ b/packages/third-parties/src/types/google.ts
@@ -5,9 +5,16 @@ declare global {
   }
 }
 
+type JSONValue =
+  | string
+  | number
+  | boolean
+  | JSONValue[]
+  | { [key: string]: JSONValue }
+
 export type GTMParams = {
   gtmId: string
-  dataLayer?: string[]
+  dataLayer?: { [key: string]: JSONValue }
   dataLayerName?: string
   auth?: string
   preview?: string