Angular ReactiveForms 没有获得动态价值

Question

我在 Angular 中使用反应式表单，并且我有这个 FormArray，我可以从中获取除 product_total 之外的所有值。

<tbody formArrayName="products">
  <tr *ngFor="let phone of productForms.controls; let i=index" [formGroupName]="i">
      <th scope="row">{{i+1}}</th>
      <td><input type="text" class="form-control" placeholder="Product Code" formControlName="product_code"></td>
      <td><input type="text" class="form-control" placeholder="Product Name" formControlName="product_name"></td>
      <td><input type="number" class="form-control" placeholder="Price" formControlName="product_price" #price></td>
      <td><input type="number" class="form-control"  formControlName="product_quantity" value="1" #quantity></td>
      <td><input type="number" class="form-control" value="{{(price.value || 0) * (quantity.value || 1)}}" formControlName="product_total" disabled></td>
    </tr>
  </tbody>

如何为打字稿代码中的每个表单组获取product_total 值？ 附言我在 HTML 代码中获取值，但不是在打字稿代码中

打字稿代码是：

constructor(private fb: FormBuilder) { }

ngOnInit() {
const product = this.fb.group({
  product_code: [],
  product_name: [],
  product_price: [],
  product_quantity: [1],
  product_total: []
});

this.myForm = this.fb.group({
  customer_name: '',
  customer_phone: '',
  customer_address: '',
  products: this.fb.array([product]),
  subtotal: Number,
  discount: Number,
  cgst: Number,
  sgst: Number,
  total_price: Number,
});
}

get productForms() {
  return this.myForm.get('products') as FormArray;
}


async submitForm() {
    const myForm = this.myForm.value;
    this.invoice = {
      products: myForm.products,
    };
    console.log(this.invoice.products);

  }

Answer 1

已编辑，之前的代码有 {{ }}，但如果我们使用 [value] 就不用放 {{ }}，更新代码

你不必总属于formGroup

<input type="number" class="form-control" disabled
    [value]="phone.get('product_price').value *( phone.get('product_quantity').value)" >

如果您认为有必要，您可以在提交时制作地图

submit(form){
   if (form.valid)
   {
      let data={
             //all properties of for.value
             ...form.value,
             //but products was products "mappeated"
             products:form.value.products.map(v=>{
             return {
               //Which each product, return 
               ...v,   //all de properties of products +
               total:v.product_price*v.product_quantity  //total
          }})
        }

      console.log(data);
   }

Answer 2

我有一个类似的逻辑要实现。我在控制器中使用了这样的东西：

ngOnInit() {
    this.formGroup = this.formBuilder.group({
        price: ['', [Validators.required]],
        quantity: ['', [Validators.required]],
        total: ''
    });

    this.formGroup.valueChanges.subscribe(change => {
        this.priceChanges()
    })
}

priceChanges() {
    let price = parseFloat(this.formGroup.value.price);
    let quantity = parseInt(this.formGroup.value.quantity);

    if (!isNaN(price) && !isNaN(quantity)) {
        let totalCost = (price * quantity).toFixed(2);
        this.formGroup.controls['total'].setValue(totalCost, { emitEvent: false })
    }
}

处理 FormArray 的编辑版本：

请注意在您的两个输入中添加的(ngModelChange)="detectValueChange(i)"：

<tbody formArrayName="products">
    <tr *ngFor="let phone of productForms.controls; let i=index" [formGroupName]="i">
        <th scope="row">{{i+1}}</th>
        <td> <input type="text" class="form-control" placeholder="Product Code" formControlName="product_code"></td>
        <td> <input type="text" class="form-control" placeholder="Product Name" formControlName="product_name"></td>
        <td><input type="number" class="form-control" placeholder="Price" formControlName="product_price" #price (ngModelChange)="detectValueChange(i)"></td>
        <td><input type="number" class="form-control" formControlName="product_quantity" value="1" #quantity (ngModelChange)="detectValueChange(i)"></td>
        <td><input type="number" class="form-control" value="{{(price.value || 0) * (quantity.value || 1)}}" formControlName="product_total" disabled></td>
    </tr>
</tbody>

然后，类似于我原来的解决方案，但现在在 'products' 数组上进行索引

detectValueChange(index: number){
    let controls = this.formGroup.get('products') as FormArray;
    this.changeTotal(controls[index])
}

changeTotal(control) {
    let price = parseFloat(control.value.product_price);
    let quantity = parseInt(control.value.product_quantity);
    if (!isNaN(price) && !isNaN(quantity)) {
        let totalCost = (price * quantity).toFixed(2);
        control['product_total'].setValue(totalCost, { emitEvent: false })
    }
}