Angular 2 conditional Validators.required?

Question

How should I go about conditionally requiring a form field? I made a custom validator, but the conditional variables that I pass to the custom validator are static and remai

Answer 1

I created a validator that accepts a function callback which allows me to make the validator reusable, but I can't seem to find a good way to make sure I call updateValueAndValidity() on the control with this validator without having to manually call it when the other control's value changes.

Validator

export class ValidationService {
    static conditionalRequired = (isRequiredFunction: Function) => {
        return (control: Control) => {
           if (!control.value && isRequiredFunction())
           ...

Component Page

private myControl1: Control = 
    new Control("", ValidationService.conditionalRequired(() => 
        { return this && this.model && this.model.SomeProperty === 'SomeValue' } ));

private myControl2: Control = 
    new Control("", 
    ValidationService.conditionalRequired(this.isControl2Required.bind(this)));

isControl2Required() { 
    return someCondition;
}