show related message to input

this is my codes, how can i display related error message to input i used array for name of input name="name_fa[]", i did like this but its doesnt work

  <input type="text" value="" name="name_fa[]" id="" class="form-control">
            @if ($errors->has('name_fa.'.$key))
            <div class="invalid-feedback">
              <strong></strong>
            </div>
            @endif

via Chebli Mohamed