Validate multipart body with @ts-rest/fastify

[mbenedettini]

I was trying to get @ts-rest/fastify to validate a multipart body and ended up making this modification for it to happen.

Am I in the right direction? If so, I'm happy to fix types and add tests to make this a proper contribution.

If not, can you point me how I should address validation for a scenario like this where I have a contract as follows and I'm also using @fastify/multipart to get streams for uploaded files? I couldn't find any other place where to hook up such validation:

import { MultipartFile as MultipartFileFastify } from "@fastify/multipart";
const MultipartFile: z.ZodType<MultipartFileFastify> = z.any();
const Schema = z.object({
  from: z.string(),
  to: z.string(),
  text: z.string().optional(),
  subject: z.string().optional(),
  message: z.string().optional(),
  attachmentStreams: z.array(MultipartFile).optional(),
});

Thanks! Mariano.

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[Gabrola]

Just use attachFieldsToBody: 'keyValues' when registering @fastify/multipart

[mbenedettini]

It doesn't work for the reason I submitted this PR: body values are no longer the values itself but objects from which you need to read the key value.

Here's a minimal proof of concept that reproduces the issue: https://github.com/mbenedettini/ts-rest-fastify-multipart-proof

[Gabrola]

@mbenedettini It's not validating because you are using a pure typescript type for your schema, not a Zod schema. attachFieldsToBody: 'keyValues' will set the values directly in body, not in .value fields.

If you set the body to this it should work.

z.object({
  requiredField: z.string(),
  file: z.instanceof(Buffer),
})

[mbenedettini]

@Gabrola thanks, that works. For the record, this is how I defined the contract:

import { MultipartFile } from "@fastify/multipart";
const Multipart: z.ZodType<MultipartFile> = z.any();
const BodySchema = z.object({
  requiredField: z.string(),
  file: Multipart,
});