Describe the feature you'd like to request

Basically I automated the client to parse every object with a File into FormData and did the splitLink, but sadly there's no way to automate this on the server, so I always need to verify and parse on the input (something that I can end up forgeting, specially in larger projects).

Example of client code:

export const client = createTRPCClient<AppRouter>({
	links: [
		function formDataLink() {
			return ({ op, next }) => {
				return observable((observer) => {
					if (!containsFile(op.input as Record<string, unknown>)) {
						op.input = objectToFormData(op.input);
					}
					return next(op).subscribe({
						next(value) {
							observer.next(value);
						},
						error(err) {
							observer.error(err);
						},
						complete() {
							observer.complete();
						},
					});
				});
			};
		},
		loggerLink(),
		splitLink({
			condition: (op) => isNonJsonSerializable(op.input),
			true: httpLink({
				transformer: transformer,
				url: `${getBaseUrl()}/api/trpc`,
			}),
			false: httpBatchLink({
				transformer: transformer,
				url: `${getBaseUrl()}/api/trpc`,
			}),
		}),
	],
});

Describe the solution you'd like to see

Currently, transformer is not called when you pass a FormData and goes directly into the input validation. I would suggest a way to handle non string/json in the server. Maybe transformFormData?

Describe alternate solutions

• Always remember to wrap input into zfd.formData
• Hack a way to pass the correct body to trpc in the server before it reaches it.

Additional information

No response

👨‍👧‍👦 Contributing

• 🙋‍♂️ Yes, I'd be down to file a PR implementing this feature!