title: Angular form validation failed, caused some problems?
body: <p>I have this form or formarray and book model:</p>
  
  <pre><code>class Book {
    id: number;
    active: boolean;
    name: string;
  }
  </code></pre>
  
  <pre><code>bookForm: FormGroup;
  
  results: Book[];
  
  ngOnInit() {
    this.results = [
      {id: 1, active: true, name: aaa},
      {id: 2, active: true, name: bbb},
      {id: 3, active: true, name: ccc},
    ];
  
    this.bookForm = this.fb.group({
      bookArray: this.fb.array(results.map(res =&gt; this.fb.group({
        id: [res.id],
        active: [res.active],
        name: [res.name, {
          validators: [BookValidators.required(`name`)],
          asyncValidators: [BookValidators.unique(`name`, (value: string) =&gt; {
                return this.service.checkNameUnique(value, res.id);
          })],
          updateOn: 'blur'
        }]
      })))
    });
  }
  </code></pre>
  
  <p>So I initiate formArray with the existing results and show this formArray tables</p>
  
  <pre><code>id   active   name
  1     true    aaa
  2     true    bbb
  3     true    ccc 
  </code></pre>
  
  <p>in this table, the name column is editable. When I edit <code>'aaa'</code> to <code>'bbb'</code>, the form validation will fail obviously, cause it has unique validation with <code>updateOn: 'blur'</code>. question is: if I keep this change: <code>'aaa' -&gt; 'bbb'</code>. then click other name fields, other name fields cannot be edited. This seems reasonable, But I just don't need it.</p>