Asymmetrik/ngx-starter

import { Attribute, Directive, forwardRef } from '@angular/core';
import { AbstractControl, NG_VALIDATORS, ValidationErrors, Validator } from '@angular/forms';

@Directive({
    selector:
        '[notWhitespace][formControlName],[notWhitespace][formControl],[notWhitespace][ngModel]',
    providers: [
        {
            provide: NG_VALIDATORS,
            useExisting: forwardRef(() => NotWhitespaceValidator),
            multi: true
        }
    ],
    standalone: true
})
export class NotWhitespaceValidator implements Validator {
    constructor(@Attribute('notWhitespace') public notWhitespace: string) {}

    validate(c: AbstractControl): ValidationErrors | null {
        const value = c.value;

        if (value && value.trim().length === 0)
            return {
                notWhitespace: false
            };
        return null;
    }
}