title: Setting validators on formgroup
body: <p>Ive looked at multiple questions and all the answers are for setting the validators on a form group. I know how to this using the form builder as shown below.</p>
  
  <pre><code> this.userForm = this.fb.group({
    id: '',
    firstName: ['', [Validators.required]],
    lastName: ['', [Validators.required]],
    email: ['', [Validators.required]],
    phoneNumber: ['', [Validators.required]],
    jobTitle: ['', [Validators.required]],
    team: ['', [Validators.required]],
    passwords: this.fb.group({
      password: '',
      confirmPassword: ''
    },{
      validator: Validators.compose([PasswordValidators.MatchPassword, PasswordValidators.PasswordRequirements])
    }),
    userValues: this.fb.array([])
  });
  </code></pre>
  
  <p>Now my component has two modes, add and edit. If the mode is add then the password controls should use the required validator. I check the mode and if its not in edit mode i want to update the validators on the passwords formgroup to include the required validator. I have tried this in the ngInit event as shown below.</p>
  
  <pre><code> // if not edit mode then the password fields are required, so we overwrite the default validators.
  if(!this.isEditMode)
  {
    console.log("user form mode: " + this.isEditMode)
    const passwordForm = &lt;FormGroup&gt;this.userForm.controls['passwords'];
  
     // try to set the validators on the form group as a whole.
    passwordForm.setValidators([PasswordValidators.MatchPassword, PasswordValidators.PasswordRequirements, Validators.required]);
    // try to set the password on the individual control.
    passwordForm.controls['password'].setValidators([PasswordValidators.MatchPassword, PasswordValidators.PasswordRequirements, Validators.required]);
  
  }
  </code></pre>
  
  <p>Now the first attempt where i try to update the validators in the form group as a while makes no difference. The second attempt where we update the individual form control causes my validator to throw exceptions. So is it possible for me to apply it to the form group without having to change the way my validator works. The validator can be seen below.</p>
  
  <pre><code>import { AbstractControl, ValidatorFn } from '@angular/forms';
  
  export class PasswordValidators {
  
      static MatchPassword(AC: AbstractControl){
          let password = AC.get('password').value; // to get value in input tag
          let confirmPassword = AC.get('confirmPassword').value; // to get value in input tag
  
           if(!password || password == "")
           {
               return null;
           }
  
           if(password != confirmPassword) {
               AC.get('confirmPassword').setErrors( {MatchPassword: true} );
           } else {
               return null;
           }
      }
  
      // Ensures the password meets the minimum standard. Password should be at least 8 char, contain one numeric, one character, and one special character.
      static PasswordRequirements(AC: AbstractControl) {
          let password = AC.get('password').value;
  
          if(!password || password == "")
          {
              return null;
          }
  
          if(password != password.match("^(?=.*?[A-Z])(?=.*?[a-z])(?=.*?[0-9])(?=.*?[#?!@$%^&amp;*-]).{8,}$")) {
              AC.get('password').setErrors({PasswordRequirements: true})
          } else {
              return null;
          }
  
      }
  }
  </code></pre>
  
  <p>Any suggestions on how i can achieve this would be great. Cheers.</p>