title: Patching Items Doesn't Update Validity in Angular
body: <p>I've a problem because after i submit the form, even though there's a value, the "field is required" doesn't disappear. It supposed to disappear. Is there something wrong with my validity? Please see this link <a href="https://stackblitz.com/edit/patch-info-using-id-and-index-vfryh6?file=app/app.component.ts" rel="nofollow noreferrer">See this link</a></p>
  
  <blockquote>
    <p>TS</p>
  </blockquote>
  
  <pre><code>patchValues(id, i) {
  let x = (&lt;FormArray&gt;this.addForm.controls['rows']).at(i);
  
  const selectedIngredient = this.ingredients.find(y =&gt; y.id == id);
  
  x.patchValue({
    unit_price: selectedIngredient.price
  });
  </code></pre>
  
  <p>}</p>