带有 rxjs 订阅的 angular 中的“属性是只读的”

Question

我有一个数组问题：
当我尝试在 countBrends() 函数中编辑“brands.count”时，出现错误“count is read only” 。
你有什么建议吗？
代码：

allCars:Car[] 
brands:BrandCB[]
types:TypeCB[]
arr:any[] = [{count:1},{count:2},{count:3}]

constructor( private store:Store<StoreState>){ }

ngOnInit(): void {
    this.store.dispatch(carsActions.getAllCars())
    this.store.dispatch(brandsActions.getBrands())

    this.store.pipe(select(carsSelectors.getAllCars)).subscribe(
        cars => {
            this.allCars = [...cars]
        }
    )
    this.store.pipe(select(brandsSelectors.getBrands)).subscribe(
        brands => {
            this.brands = this.countBrands([...brands])
        }
    )

}

// it counts how many cars there are of the same brand 
// and enters the number in the "count" property of brands
countBrands(brands):BrandCB[]{
    return brands.forEach( brand =>{
        let count = 0
        this.allCars.forEach( car => {
            car.brand == brand.name ? count++ : null
        })
        brand.count = count
    })
}

Answer 1

无论如何，您应该在可能的情况下避免突变。 在这种情况下，我认为您应该通过增加数量来分配品牌的新价值，因为所有状态都是不可变的，您不能只在组件中分配新价值。