fetchToken response error: TypeError: immutable

[phil-w]

Dexie Cloud works great with the built-in magic code email auth, but I want to make it work with my own existing authorization. I'm using the Dexie Cloud, and Sveltekit latest versions. I configured the fetchTokens function, and provided it a POST endpoint which is being hit correctly with the "claims" correctly filled in, and the public key is there too. The sign in POST is being made to the Dexie Cloud end point, which is this:

Token Request

// Request token from Dexie Cloud database.
const tokenResponse = await fetch(`https://${PUBLIC_DEXIE_DB}/token`, {
 	method: "POST",
 	headers: { "Content-Type": "application/json", "Accept": "application/json"  	},
 	body: JSON.stringify({
 		grant_type: "client_credentials", scopes: ["ACCESS_DB"], public_key,
 		client_id: DEXIE_CLIENT_ID, client_secret: DEXIE_CLIENT_SECRET, claims: claims
 	})
})
...
setHeaders({'cache-control':'no-store'}) 	    // Not sure I really care about this.
return tokenResponse	                            // Return token to client.

Token Response

I can examine the response structure, which has cookies in it and other stuff. It looks ok.
The sample Dexie Cloud code has a callback like this below.

fetchTokens: (p) => {
	fetch(`${baseUrl}/api/user/dexie`, {
		method: 'POST', credentials: 'same-origin',
		headers: { 'Content-Type': 'application/json' }, body: JSON.stringify(p)
  	}).then(res => res.)
}

Crash Dump

{
  error: TypeError: immutable
      at appendHeader (node:internal/deps/undici/undici:2848:15)
      at _Headers.append (node:internal/deps/undici/undici:2979:16)
      at Module.add_cookies_to_headers (D:\Sveltkit\node_modules\@sveltejs\kit\src\runtime\server\cookie.js:247:11)
      at D:\Sveltkit\node_modules\@sveltejs\kit\src\runtime\server\respond.js:330:6
      at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
      at async authorizationHandle (D:\Sveltkit\src\hooks.server.js:43:11)
      at async cors (D:\Sveltkit\src\hooks.server.js:125:19)
      at async Module.respond (D:\Sveltkit\node_modules\@sveltejs\kit\src\runtime\server\respond.js:319:20)
      at async file:///D:/Sveltkit/node_modules/@sveltejs/kit/src/exports/vite/dev/index.js:524:22,
  route: '/api/user/dexie',
...
}

Remembering that this is a fetch which is forwarding the results of the first fetch, it seems like it's failing because it's trying to tinker with the response, adding cookies or headers, looking at the crash. So I tried to clone "res", then pass the clone back, but that doesn't help.

• Sveltekit uses (I think) it's own fetch, so it's possible my problems are related to that.
• Has anyone made this work with Sveltekit, or otherwise have any ideas how I can hack around this?

[phil-w]

Some progress:

1. I wrote a thing which bypasses the Dexit proxy, doing the "token request" fetch when I press a button . It calls https://${PUBLIC_DEXIE_DB}/token directly and looks at what comes back. It didn't work, until....
2. I changed the return tokenResponse from that endpoint to return new Response(tokenResponse.body), and it returns with a body which looks like {"type":"tokens","accessToken":"eyJhbGciOi... which I'm guessing is what I want.
3. I added an await on the front of the fetch request, else that's definitely not going to work!

[phil-w]

Got it. I'm mixing promises with waits, numpty error.

The fetchTokens callback should be:

fetchTokens: async (p) => {
	const r = await fetch(`${baseUrl}/api/user/dexie`, {
		method: 'POST', credentials: 'same-origin',
		headers: { 'Content-Type': 'application/json' }, body: JSON.stringify(p)
  	})
	return await r.json()
}
~~

Job done in **Sveltekit**.