Date deserialization in TRPC mutations not working in edge runtimes

[aldebout]

Cross-posting t3-oss/create-t3-turbo#1110 to get your eyes on it 😉

It looks like superjson silently fails to deserialize Date objects in edge runtimes, only in TRPC mutations (not queries).

More details in the original issue, including repro.

[Skn0tt]

Interesting, thank you! If you can come up with a minimal repro of this that behaves similar to how TRPC uses SuperJSON, but that doesn't include TRPC itself, then i'm happy to take a look and see if there's something to fix here.

[aldebout]

@Skn0tt here is a repro repo https://github.com/aldebout/superjson-edge-repro.
It's the nextjs app start with only superjson added.

To see the issue: pnpm i, pnpm dev, then post

{
    "json": {
        "startDate": "2024-12-20T14:00:00.000Z"
    },
    "meta": {
        "values": {
            "startDate": [
                "Date"
            ]
        }
    }
}

on /api.

If we set the runtime to node (export const runtime = 'nodejs') it works, if we set it to edge (export const runtime 'edge') it fails.

[aldebout]

Playing with it some more, it looks like there's an issue in both serialization and deserialization of Dates in the local nextjs edge runtime. If I serialize { startDate: new Date("2024-12-20T14:00:00.000Z") }, then result.json.startDate instanceof Date is true.

I tried running the tests using environment: 'edge-runtime' in vitest.config.mjs but they're still passing, I'm wondering if I'm missing something.

[Skn0tt]

Take a look at the code around

superjson/src/transformer.ts

Lines 79 to 84 in 0130a80

	simpleTransformation(
	isDate,
	'Date',
	v => v.toISOString(),
	v => new Date(v)
	),

and specifically at the implementation of isDate. I'm not very familiar with the internals of edge-runtime, but I could imagine that their Date implementation behaves slightly different from what SuperJSON expects, and from what happens on Node.js and in the browser. Try testing it exclusively within production - it seems like running edge-runtime locally is very different from prod: https://edge-runtime.vercel.app/#using-the-edge-runtime-locally

[aldebout]

I'll switch the runtime depending on the environment and let you know how it goes.

I was looking into the source code but I'm having issues linking and debugging locally so I'll take a break from that.

FWIW undefined is also broken in this setup, I'm wondering what the pattern is.

[aldebout]

The runtime switch is hard because nextjs requires a statically analyzable export :/

I dug deeper and the issue looks very similar to #242: in my local nextjs edge env,

superjson/src/is.ts

Line 16 in 0130a80

return Object.getPrototypeOf(payload) === Object.prototype;

returns false even though I have a plain object.

I don't really know how to fix this because (as you said) it's not very clear to me what exactly runs nextjs edge locally. In the meantime I think I'll switch to another lib.

[Skn0tt]

I could imagine that the NaN check here doesn't work on Edge runtime:

superjson/src/is.ts

Line 47 in 0130a80

payload instanceof Date && !isNaN(payload.valueOf());

If you or anybody else ends up doing more investigation on this, please post your results. Happy to write a fix.