title: How to dynamically add formgroup controls to formarray in angular while the state is managed by ngrx-forms?
body: <p>I am using an ngrx-forms library for managing states of my form.</p>
  <p>This is the library : <a href="https://ngrx-forms.readthedocs.io/" rel="nofollow noreferrer">https://ngrx-forms.readthedocs.io/</a></p>
  <p>It works well with simple inputs for me. But when it comes to dynamic controls, I am not sure how to use it.</p>
  <p>For example, let's say we have a form:</p>
  <pre class="lang-js prettyprint-override"><code>myform = this.fb.group({
    topic: '',
    books: [''],
    languages: [''],
  })
  </code></pre>
  <p>now the languages controls looks like this :</p>
  <blockquote>
  <p>{language: '', code: ''}</p>
  </blockquote>
  <p>How can I dynamically add the above control to the languages array of form builder when the user clicks add languages button? I can do it with a regular FormBuilder. No problem.</p>
  <p>but when it comes to managing state using ngrx coupled with ngrx-forms how can I create a reducer function to add language controls dynamically?</p>