What are the advanced features of TypeScript class-validator?

What are the advanced features of TypeScript class-validator?

TypeScript class-validator offers several advanced features like custom decorators, validation groups, and asynchronous validation. Would you like to explore any specific feature?

Can you explain how to create custom decorators?

Sure! To create a custom decorator, you can use the registerDecorator function. This allows you to define your own validation logic. Would you like a code example?

Yes, please provide a code example.

Here's a simple example:

import { registerDecorator, ValidationOptions } from 'class-validator';

export function IsPositive(validationOptions?: ValidationOptions) {
    return function (object: Object, propertyName: string) {
        registerDecorator({
            name: 'isPositive',
            target: object.constructor,
            propertyName: propertyName,
            options: validationOptions,
            validator: {
                validate(value: any) {
                    return typeof value === 'number' && value > 0;
                },
            },
        });
    };
}

This custom decorator checks if a number is positive. Would you like to know more about validation groups?

What are validation groups?

Validation groups allow you to group validations and apply them conditionally. This is useful for scenarios where different validations are needed for different contexts.