Angular 4 remove required validator conditionally

Question

In Angular 4 app I have a form model like this:

this.form = this._fb.group({
    title: [\'\', [Validators.required, Validators.minLength(3), Validators.maxLengt         


        

Answer 1

this.fromName.get("formControlName").setValidators([Validators.required]);//setting validation
this.fromName.get("formControlName").setErrors({'required':true});//error message
this.fromName.updateValueAndValidity();//update validation


this.fromName.get("formControlName").clearValidators([Validators.required]);//clear validation
this.fromName.get("formControlName").setErrors(null);//updating error message
this.fromName.updateValueAndValidity();//update validation