OmitType "omits" @Transform decorators

I’m submitting a…

[ ] Regression 
[x] Bug report
[x] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead post your question on Stack Overflow.

Current behavior

I have a base class DTO for query params(using validation and @Transform decorators). When extending this with OmitType the validation decorators are taken into consideration, but not the @Transform. As a result, cannot create reusable objects and validation fails due to missing transformation(e.g from string to Date etc.)

Extending the class in the “normal” way it works like expected

Edit: Actually this seems to manifest when having a bigger class hierarchy QueryParamsDto ExtraQueryParamsDto extends QueryParamsDto FinalQueryParamsDto extends OmitType(ExtraQueryParamsDto, [‘some_property’])

It seems in the FinalQueryParamsDto tranformation decorators are not picked up if defined in the base class QueryParamsDto

[shahen94]

Seems still actual

"@nestjs/common": "^8.2.4",
"@nestjs/config": "^1.1.6",
"@nestjs/core": "^8.2.4",
"@nestjs/swagger": "^5.1.4",

export class FindAllQueryDto {
  @ApiPropertyOptional()
  @IsString()
  @IsOptional()
  userId?: string;

  @Transform(({ value }) => Array.isArray(value) ? value : [value])
  @ApiPropertyOptional()
  @IsString({ each: true })
  @IsOptional()
  enterprisesIds?: string[];
}

export class FilterUsersDto extends OmitType(FindAllQueryDto, ['userId']) {}

In the controller

@Get('users')
getUsers(@Query() query: FilterUsersDto) {
  console.log(query.enterprisesIds); // will not be converted array
}

curl http://localhost:3000/users?enterprisesIds=helloWorld

Expected

enterprisesIds should be [ 'helloWorld' ]

Actual

enterprisesIds equals helloWorld

[jmcdo29]

If it’s still actually happened does someone want to provide a minimum reproduction repository like Kamil has already asked?