Validation issues during overriding fields

[JonathanLoscalzo]

Is there an existing issue for this?

• I have searched the existing issues

Current behavior

I'm working on setting up a validation inheritance chain between UpdateDto, CreateDto, and BaseDto for my request payloads.

I recently migrated from NestJS v8 to v11.
This code used to work in v8, but that's not the main point now. What I'd really like is a more robust and reliable approach for validating complex, related types across inherited DTOs.

Sure, I could re-write all my DTOs from scratch—but I'm mid-migration, and I suspect some behavior might have changed in newer versions, which would be completely fair.

So ideally, I’m looking for:

• A better pattern or example to handle validation cleanly across inherited DTOs.
• An explanation of any known differences in validation behavior (e.g., with PartialType, PickType, OmitType, etc.) between NestJS versions.
• A way to avoid having validations silently overridden or skipped in child classes.

First, the initial code (check the gists for unit testing):

export class Base {
  @IsString()
  @Length(2, 100)
  subject?: string;
}

export class Create extends Base {
  @IsNotEmpty()
  subject: string;
}

export class UpdatePartialType extends PartialType(Create) {}

export class UpdatePartialWithPickType extends IntersectionType(
  PartialType(Create),
  PickType(Create, ['subject']),
) {}

export class UpdatePartialWithOmitType extends IntersectionType(
  OmitType(PartialType(Create), ['subject']),
  PickType(Create, ['subject']),
) {}

• Create: when there is a new object (new Create()), it validates the "not empty" decorator. But it fails validating string and length from Base.
• UpdatePartialType: it works fine when the object is "empty" (just new). But, Base validations were missing
• UpdatePartialWithPickType: when the object is new, IMO it should fail. But it doesn't. Neither it has the Base validations.
• UpdatePartialWithOmitType: better here, when the object is new, subject fails (not empty). But it continues skipping Base validations.

I have a lot of DTOs chains like these. I have detected just one, but I imagine there are others and, the lack of good testing, it might be a nightmare for next weeks.

The issue are:

• How could I force UpdatePartial*classes to have all the validations in the chain.
• Are there a config to force that? its a problem of typescript? new behavior of decorators?

The code has some tests to visualize these inconvenientes or misunderstandings from my side.
Moreover, I've opened a question issue on class-validator here: typestack/class-validator#2608

Minimum reproduction code

https://gist.github.com/JonathanLoscalzo/c6b4e804230b3231e1a9dc8fb32c1d9c

Steps to reproduce

1. create an empty nest project
2. copy the gists
3. run the tests

Expected behavior

• Validation on fields should be chained during inheritance, instead of overwritten
• If it can't be solved or is a new behavior, leave a comment or an info section describing the situation

Package version

@nestjs/mapped-types@2.1.0, @nestjs/*@11.0.7

Node.js version

v22.15.0

In which operating systems have you tested?

• macOS
• Windows
• Linux

Other

No response

[JonathanLoscalzo]

for class-validator@0.11.1 is working correctly. Current version is 0.14.2.