Class-validator: @IsOptional() + @NotEquals(null) not working

[chutiphon-k]

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
}

[vlapo]

What are your ValidatorOptions https://github.com/typestack/class-validator#passing-options. Maybe you skip missing properties.

[chutiphon-k]

I don't set ValidatorOptions. I use the default.

[tmtron]

This does not work, because @IsOptional() notices that the value is null and then all other validators (including @NotEquals(null)) are ignored

@IsOptional() docs:

Checks if given value is empty (=== null, === undefined) and if so, ignores all the validators on the property.

I could also not make this work the other way around: Stackoverflow: "How to allow null, but forbid undefined?"

[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

[chutiphon-k]

Great, it works. 😄

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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