@IsOptional() + @NotEquals(null) not working

I want to validate displayName with optional and not equal null but it not working. it does not validate @NotEquals(null).

export class UpdateDto implements Partial<UserEntity> {
  @ApiProperty()
  @IsOptional()
  @NotEquals(null)
  displayName?: string;
}

this case is pass input:

{
 displayName: null
}

[tmtron]

Recommended I suggest, that you remove @NotEquals(null) and set skipMissingProperties to true in the validation options
see this Stackblitz example

Alternative

When you want to use the default validation options, you can use ValidateIf to make it work:

export class UpdateDto {
  @IsString()
  @NotEquals(null)
  @ValidateIf((object, value) => value !== undefined)
  displayName?: string;
}

This will pass the validation when displayName is undefined or a string, but fail for null.

see this Stackblitz example

[lock[bot]]

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