在使用Angular 12中的FormControls时，可以在内嵌两个FormArrays的formGroup中使用。以下是具体的代码示例：

1. 创建表单模型并初始化数据

import { Component, OnInit } from '@angular/core';
import { FormBuilder, FormGroup, FormArray } from '@angular/forms';

@Component({
  selector: 'app-nested-form-array',
  templateUrl: './nested-form-array.component.html',
  styleUrls: ['./nested-form-array.component.css']
})
export class NestedFormArrayComponent implements OnInit {
  myForm: FormGroup;

  constructor(private fb: FormBuilder) { }

  ngOnInit() {
    this.myForm = this.fb.group({
      customers: this.fb.array([
        this.fb.group({
          name: '',
          orders: this.fb.array([
          ])
        })
      ])
    });

    this.addOrder();
  }

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

  get orders() {
    return this.customers.controls[0].get('orders') as FormArray;
  }

  addOrder() {
    this.orders.push(this.fb.group({
      product: '',
      quantity: ''
    }));
  }
}

2. 在HTML模板中使用表单控件并显示数据

  

    

      Name:
      
    
    

      

        

          Product:
          
        
        

          Quantity:
          
        
      
    
  

在以上示例代码中，我们创建了一个FormGroup，并在其内部嵌套了两个FormArray，分别为“customers”和“orders”