ParseArrayPipe `optional: true` returns unwanted default value `[ '' ]`

Bug Report

Current behavior

console.log(tagIds); prints [ '' ] regardless of DefaultValuePipe. If optional is false, it throws Bad Request exception “Validation failed (parsable array expected)”.

Input Code

@Get()
findSomething(
  @Query(
    'tagIds',
    new DefaultValuePipe([]),
    new ParseArrayPipe({ items: Number, optional: true }),
  )
  tagIds: number[],
) {
  console.log(tagIds);
  // return something
}

Expected behavior

I should be undefined or empty array [].

Possible Solution

Environment

Nest version: 7.6.18

 
For Tooling issues:
- Node version: 12.18.0
- Platform:  Mac

Others:

[jmcdo29]

I’ll leave this here again: https://github.com/nestjs/nest/issues/7926#issuecomment-904097118

[jmcdo29]

I’ll leave this here again: #7926 (comment)

Thankfully, micalevisk provided the repository that you requested so I thought I don’t have to do the exact same thing. Am I wrong? And apparently, this is now a matter of decision, not a bug. So you may close this issue unless you want to discuss further.

When I wrote the original comment, the repository had not been added, or I had missed it because edits don’t show up in emails and I had already been following the conversation. Seeing as we have a reproduction, I can take a look later myself. Thanks for pointing out out