我对angular 2/4和一般的web开发还不熟悉。我有一张表格,它收集购买表格中不同产品的信息。
我已经构建了一个变体的表单组的formarray,如下面的html所示。

<form [formGroup]="this.purchaseInvoiceItemVariantsForm" novalidate>
    <div formArrayName="variants">
        <div *ngFor="let variant of this.purchaseInvoiceItemVariantsForm.controls.variants.controls; let i = index">
            <div [formGroupName]="i">
                <md-input-container>
                    <input mdInput placeholder="Product Code"  formControlName="productBarcode" class="input--small" [readonly]="this.mode == 'view'">
                </md-input-container>
                <md-input-container>
                    <input mdInput placeholder="Color" formControlName="variant1" class="input--small" [readonly]="this.mode == 'view'" required>
                </md-input-container>
                <md-input-container>
                    <input mdInput placeholder="Size" formControlName="variant2" class="input--small" [readonly]="this.mode == 'view'" required>
                </md-input-container>
                <md-input-container>
                    <input mdInput placeholder="MRP" formControlName="mrp" class="input--small" [readonly]="this.mode == 'view'">
                </md-input-container>
                <md-input-container>
                    <input mdInput placeholder="Purchase Price" formControlName="purchasePrice" class="input--small" [readonly]="this.mode == 'view'"
                        required>
                </md-input-container>
                <md-input-container>
                    <input mdInput placeholder="Sell Price" formControlName="sellPrice" class="input--small" [readonly]="this.mode == 'view'"
                        required>
                </md-input-container>
                <md-input-container>
                    <input mdInput placeholder="Quantity" formControlName="variantQuantity" class="input--small" [readonly]="this.mode == 'view'" required>
                </md-input-container>
                <md-input-container>
                    <input mdInput placeholder="Discount" formControlName="variantDiscount" class="input--small" [readonly]="this.mode == 'view'">
                </md-input-container>
                <button md-icon-button (click)="removeVariant(i)" color="warn" *ngIf="purchaseInvoiceItemVariantsForm.controls.variants.length > 1 && this.mode != 'view'"><md-icon>delete</md-icon></button>
            </div>
        </div>

现在,一旦用户添加了3个变体,我希望能够监听formcontrol“productbarcode”的valuechanges,以便从数据库中获取颜色和大小的详细信息。
有什么建议可以做到这一点吗?
提前谢谢!
当做,
纳维

最佳答案

我们可以做一个版本的valueChanges,当variants-数组长度为a>= 3时开始监听。然后我们听条码的每一个变化。
我假设您有一个函数,可以在其中向variants数组添加新控件,我们可以在那里实现它:

addVariant() {
  // code here for adding control

  // check length
  if(this.purchaseInvoiceItemVariantsForm.get('variants').length >= 3) {
    // iterate each object in array
    for(let val of this.purchaseInvoiceItemVariantsForm.get('variants').controls) {
      // listen to changes in each barcode, if change, do something!
      val.get('productBarcode').valueChanges.subscribe(data => {
      console.log(val.get('productBarcode').value)
      // do something!
      })
    }
  }
}

Demo

09-17 09:15