Conditional Validation¶

The conditional validation decorator (@ValidateIf) can be used to ignore the validators on a property when the provided condition function returns false. The condition function takes the object being validated and must return a boolean.

Basic Usage¶

import { ValidateIf, IsNotEmpty } from 'class-validator';

export class Post {
    otherProperty: string;

    @ValidateIf(o => o.otherProperty === 'value')
    @IsNotEmpty()
    example: string;
}

In this example, the validation rules applied to example won't be run unless the object's otherProperty is "value".

Important Notes¶

When the condition is false, all validation decorators are ignored, including @IsDefined
The condition function takes the object being validated as a parameter
The condition function must return a boolean
Multiple @ValidateIf decorators can be used on the same property

Advanced Example¶

import { ValidateIf, IsNotEmpty, IsString } from 'class-validator';

export class User {
    @IsString()
    type: string;

    @ValidateIf(o => o.type === 'admin')
    @IsNotEmpty()
    adminKey: string;

    @ValidateIf(o => o.type === 'user')
    @IsNotEmpty()
    userKey: string;
}