title: Angular How to patch value in the form array
body: <p>I am using Angular8 and reactive forms. My ngOnInit is:</p>
  <pre class="lang-js prettyprint-override"><code>ngOnInit(): void {
    this.makeForm = this.fb.group(
      year: ['', Validators.required],
      amount: ['', Validators.required],
      desc: ['', Validators.required],
      details: new FormArray([
        this.det(),
      ]
    );
  }
  
  det() {
    return new FormGroup({
      for: new FormControl(''),
      remarks: new FormControl('')
    });
  }
  </code></pre>
  <p>I have the data from the backend to patch the array:</p>
  <pre class="lang-json prettyprint-override"><code> {
    &quot;amount&quot;: 9000,
    &quot;year&quot;: 1996,
    &quot;id&quot;: 1,
    &quot;desc&quot;: &quot;P1&quot;,
    &quot;details&quot;: [
      {
        &quot;id&quot;: 1,
        &quot;remarks&quot;: &quot;ok&quot;,
        &quot;for&quot;: &quot;1&quot;
      },
      {
        &quot;id&quot;: 24,
        &quot;remarks&quot;: &quot;OK&quot;,
        &quot;for&quot;: &quot;1&quot;
      },
      {
        &quot;id&quot;: 25,
        &quot;remarks&quot;: &quot;OK&quot;,
        &quot;for&quot;: &quot;1&quot;
      }
    ]
   }
  
  </code></pre>
  <p>I commonly patch the values with this method:</p>
  <pre class="lang-js prettyprint-override"><code>getppredit() {
    let data:any = this.shareService.ParentShare.value;
    let id = data.id;
    this.dataService.getdataEdit(id)
      .subscribe((result: any) =&gt; {
        let no = result.no;
        let year = result.year;
        this.makeForm.patchValue({
          no: no,
          year: year
        });
    });
  }
  
  </code></pre>
  <p>The above code is used for normal patch, but how to patch the value inside of an array dynamically using Angular8's reactive forms?</p>