Angular 6 表单数组补丁值的值变化

Question

下面是我的 FormArray，我想根据另一个输入的值变化来更新一个输入。每当用户更改产品时，服务将获取价格和 taxPercent，需要为表单数组中的该索引修补，当添加数量时，我想修补 totalAmount。当它只是一个 formControlElements 通过订阅各自的 valueChanges 和路径各自的字段时，这很容易。我怎样才能在 FormArray 中做同样的事情？

<div formArrayName="products" *ngFor="let product of productsArray.controls; let i=index">
      <div [formGroupName]="i">
          <div class="form-row">

              <div class="form-group col-md-4">
                  <label for="product">Product</label>
                  <select formControlName="pdt"  class="form-control" >
                      <option [value]="pdt.productPriceId" *ngFor="let pdt of productPrice">{{pdt.productName}}  -  {{pdt.size}}</option>
                  </select>
              </div>

              <div class="form-group col-md-1">
                <label for="price">Price</label>
                <input type="text" class="form-control" formControlName="price" id="price">
              </div>
              <div class="form-group col-md-1">
                <label for="taxPercent">Tax %</label>
                <input type="text" class="form-control" formControlName="taxPercent" id="taxPercent">
              </div>

              <div class="form-group col-md-1">
                <label for="quantity">Qty</label>
                <input type="text" class="form-control" formControlName="quantity" id="quantity">
              </div>

              <div class="form-group col-md-1">
                <label for="totalAmount">Amt</label>
                <input type="text" class="form-control" formControlName="totalAmount" id="totalAmount">
              </div>

            <div class="form-group col-md-1">
                <span>
                  <button class="btn btn-primary" (click)=addProduct()>Add</button>
                </span>
            </div>
            <div class="form-group col-md-1">
              <span>
                <button class="btn btn-primary" (click)=removeProduct(i)>Remove</button>
              </span>
          </div>
        </div>
      </div>
    </div>

My Value Changes 订阅 FormControl 如下所示。但我不确定如何为 FormArray

做同样的事情

this.billingForm.get('products[0].pdt').valueChanges.subscribe(
      (value) => {

          console.log(value);
          let taxPercentVal: Number = 0;
          let priceVal: Number = 0;
          this.productPrice.forEach(function (val) {
            if(value == val.productPriceId)
            {
              taxPercentVal = val.taxPercent;
              priceVal = val.price;
            }
          });

          this.billingForm.patchValue({
            products: {
              taxPercent: taxPercentVal,
              price: priceVal,
              quantity: '',
              totalAmount: '' 
            }
          })



      }
    );



    this.billingForm.get('products.quantity').valueChanges.subscribe((value) => {
          console.log(value);
          let taxPer = this.billingForm.value.products.taxPercent;
          console.log(taxPer);
          let pr = this.billingForm.value.products.price;
          console.log(pr);
          let qty = value;
          console.log(qty);
          let totAmt = (pr * qty) + ((pr * qty) / taxPer);
          console.log(totAmt);
          this.billingForm.patchValue({
            products: {
              totalAmount: totAmt
            }
          })
    })

Answer 1

您可能想在更改事件上添加一个功能。如下所示：

<div class="form-group col-md-4">
                  <label for="product">Product</label>
                  <select formControlName="pdt"  class="form-control" **(change)="onChange($event)"** >
                      <option [value]="pdt.productPriceId" *ngFor="let pdt of productPrice">{{pdt.productName}}  -  {{pdt.size}}</option>
                  </select>
</div>

您应该能够在那里捕获新产品，并可以使用数据绑定更新您的其余字段。希望对您有所帮助！

Angular 6 表单数组补丁值的值变化

Angular 6 Form Array Patch Values on Value Changes

typescript

angular

angular-reactive-forms

formarray