PonyfillBlob and nestjs class transformer package

[kanopa]

Describe the bug

I am working on a NestJS (fastify) project that uses a schema-first approach for GraphQL and I want to implement a file upload feature. For DTO validation, I am using class-validator in combination with class-transformer, and I am applying a global validation pipe via NestJS's ValidationPipe from the @nestjs/common module.

I am encountering an issue when handling file uploads. Specifically, I receive a TypeError: Cannot read properties of undefined (reading 'length') related to PonyfillBlob. This error occurs because class-transformer attempts to create an instance of the class and encounters undefined properties, which leads to this error.

To Reproduce Steps to reproduce the behavior:

I create a demo repository with problem https://github.com/kanopa/yoga-nests-upload-issue

Maybe its better to type blobParts as nullable (private blobParts?: BlobPart[]) and add nullable to condition on 51 line?

if (blobParts?.length === 1 && isBlob(blobParts[0])) {
      return blobParts[0] as PonyfillBlob;
    }

[ardatan]

Thanks for the reproduction but could you give instructions for the reproduction?

[kanopa]

Thanks for the reproduction but could you give instructions for the reproduction?

Of course, i create repo with reproduction. Call mutation filesUpload with files as parameters, you can use any files for your choise :) Server starts on localhost:3000/graphql I prefer using altair gql client for test upload mutations

[ardatan]

Fixed in https://github.com/ardatan/whatwg-node/commit/d26157339f3896509e45cb5c73aa61164d262d56