在Angular 4反应形式中检查多行自定义验证器

我有一个非常简单的问题，我无法解决.首先，我有一个批准数量的成分.该成分有多个有效期.但是，我要检查我的转让数量"到期日是否不超过批准数量.

I have a very simple problem which I can't get it. First, I have an ingredient which has an approved quantity. And that ingredient has several expiration dates. However, I want to check if my expiration dates which has the "quantity to transfer" is not more than the approved quantity.

我应该如何检查?我已经完成了一些我无法比较的零件，因为它必须对照一个批准的数量检查几行要转移的数量".这是下面的代码链接:

How should I check this? I already finished some parts BUT this one I couldn't compare since it has to check several rows of "quantity to transfer" against the one approved quantity. Here's the code link below:

此处有分叉链接

customValidator(group: any) {
    if ((group.controls.transfer_qty.value > group.parent.parent.controls.approved_qty.value)) {
      return { out1: true }
    }
    if ((group.controls.transfer_qty.value > group.controls.available_qty.value)) {
      return { out2: true }
    }
    return null;
  }