Question

我开始在Rxjs中使用BehaviorSubject，在这方面经验有限。到目前为止，我能够获取组件中的根级参数，但访问嵌套对象会导致“无法读取未定义的属性x”。

类：

export class Basket extends X23Object {
    public BasketId: number;
    public UserID: number;
    public User: User;
    public BasketLines: BasketLine[] = [];
}

export class BasketLine extends X23Object {
    public BasketLineId: number;
    public BasketId: number;
    public ProductId: number;
    public Quantity: number;
    public Product: Product;
    public Price: number;
    public Name: string;
}
export class Product extends X23Object {
    public ProductId: number;
    public CategoryId: number;
    public Name: string;
    public Code: string;
    public Price: number;
    public Details: string;
    public Images: Image[];
    public Category: Category;
}

BasketBackendService

GetBasket() {
    return this.authHttp.get(this.apiUrl + 'api/GetBasketByUser?id=' + parseInt(this.decodedJwt['userId']), { headers: contentHeaders });
}

BasketService

private _lines: BehaviorSubject<BasketLine[]> = new BehaviorSubject([new BasketLine]);
get getLines() {
    return this._lines.asObservable();
}
loadBasket() {
    this.basketBackendService.GetBasket()
        .subscribe(
            response => {
                let lines = <BasketLine[]>response.json().basket.BasketLines;

                this._lines.next(lines);
            },
            error => console.log(error.text())
        );
}

模板（摘录）

<tr *ngFor="let line of basketService.getLines | async">
    <td><img class="login-logo" src="{{ line.Product.Images[0].ThumbUrl }}" width="100%" /></td>
    <td><a [routerLink]="['Product', { id: line.ProductId }]"> {{ line.Product.Code }} </a></td>
    <td><a [routerLink]="['Product', { id: line.ProductId }]">{{ line.Product.Name }}</a></td>
    <td class="text-right">{{ line.Price | currency:'GBP':true:'.2-2' }}</td>
    <td class="text-center">{{ line.Quantity }}</td>
    <td class="text-right">{{ line.Quantity * line.Price | currency:'GBP':true:'.2-2' }}</td>
    <td><button (click)="DeleteLine(line.BasketLineId)">Remove</button></td>
</tr>

如果删除深层嵌套对象的引用，我会返回预期的结果。

我正在尝试使用BehaviorSubject来更新多个组件，但不确定这是否是最佳解决方案！

Answer 1

代码对我来说很好，我想通过“深嵌套”你的意思是例如line.Product.Code。如果它适用于line.Quantity，则问题很可能不在BehaviorSubject中，而在于数据结构中。

我不知道您的特定用例是什么，但您根本不需要同时使用BehaviorSubject或async管道。

对于BasketService，您只能使用：

export class BasketService {
    lines: BasketLine[];

    // ...

    loadBasket() {
        this.basketBackendService.GetBasket().subscribe(
            response => {
                this.lines = <BasketLine[]>response.json().basket.BasketLines;
            },
            error => console.log(error.text())
        );
    }
}

然后只用：

渲染它

<tr *ngFor="let line of basketService.lines">
    // ...
</tr>

Rxjs在actsubject中包含深层嵌套的对象

1 个答案: