Rxjs 使用链早期阶段的先前可观察值

Question

如何使用链早期阶段（不是最后阶段）的可观察值。

我有这样的代码：

deleteGroceryStoreAndItsOwner() {

    this.groceryStoreOwnerService.getGroceryStoreOwnerSummaries(this.city.uuid)
        .flatMap((groceryStoreOwnerSummaries: GroceryStoreOwnerSummary[]) => aircraftUserSummaries.filter(groceryStoreOwnerSummary=> groceryStoreOwnerSummary.user.gender == "Male"))
        .flatMap((groceryStoreOwnerSummary: GroceryStoreOwnerSummary) => this.groceryStoreService.searchGroceryStore(this.city.uuid, groceryStoreOwnerSummary.user.uuid))
        .flatMap((groceryStoreSummary: GroceryStoreSummary) => this.groceryStoreService.getGroceryStore(groceryStoreSummary.uuid))
        .flatMap((groceryStore: GroceryStore) => this.groceryStoreService.deleteGroceryStore(groceryStore))
        .flatMap((groceryStoreOwnerSummary: GroceryStoreOwnerSummary) => this.groceryStoreOwnerService.getGroceryStoreOwner(groceryStoreOwnerSummary)) // here is where i have the problem: how can i use the observable from early stage of the chain?
        .flatMap((groceryStoreOwner: GroceryStoreOwner) => this.groceryStoreOwnerService.deleteGroceryStoreOnwer(groceryStoreOwner))
        .subscribe(() => {
            console.log("deleted grocery store")
            console.log("deleted grocery store owner")
        })
};

在删除第四个平面图中的杂货店后，我需要删除杂货店老板，这是来自第二个平面图的。

注意：

1. 每个删除方法（deleteGroceryStore和deleteGroceryStoreOnwer）都会返回一个Observable。
2. 我的应用程序的角度版本不支持管道，因此请不要使用 .pipe 给出答案。

更新：2022 年 3 月 10 日 我像这样修改了我的代码，但由于某种原因，地图中的代码没有被执行，知道为什么吗？

deleteGroceryStoreAndItsOwner() {
    this.groceryStoreOwnerService.getGroceryStoreOwnerSummaries(this.city.uuid)
        .flatMap((groceryStoreOwnerSummaries: GroceryStoreOwnerSummary[]) => aircraftUserSummaries
            .filter(groceryStoreOwnerSummary => groceryStoreOwnerSummary.user.gender == "Male"))
        .map((groceryStoreOwnerSummary: GroceryStoreOwnerSummary) => {
            this.groceryStoreService.searchGroceryStore(this.city.uuid, groceryStoreOwnerSummary.user.uuid)
                .flatMap((groceryStoreSummary: GroceryStoreSummary) => this.groceryStoreService.getGroceryStore(groceryStoreSummary.uuid))
                .flatMap((groceryStore: GroceryStore) => this.groceryStoreService.deleteGroceryStore(groceryStore))
            this.groceryStoreOwnerService.getGroceryStoreOwner(groceryStoreOwnerSummary)
                .flatMap((groceryStoreOwner: GroceryStoreOwner) => this.groceryStoreOwnerService.deleteGroceryStoreOnwer(groceryStoreOwner))
        })
        .subscribe(() => {
            console.log("deleted grocery store")
            console.log("deleted grocery store owner")
        })
};

我也尝试过这个，但仍然不起作用：

deleteGroceryStoreAndItsOwner() {
    this.groceryStoreOwnerService.getGroceryStoreOwnerSummaries(this.city.uuid)
        .flatMap((groceryStoreOwnerSummaries: GroceryStoreOwnerSummary[]) => aircraftUserSummaries
            .filter(groceryStoreOwnerSummary => groceryStoreOwnerSummary.user.gender == "Male")
            .map((groceryStoreOwnerSummary: GroceryStoreOwnerSummary) => {
                this.groceryStoreService.searchGroceryStore(this.city.uuid, groceryStoreOwnerSummary.user.uuid)
                    .flatMap((groceryStoreSummary: GroceryStoreSummary) => this.groceryStoreService.getGroceryStore(groceryStoreSummary.uuid))
                    .flatMap((groceryStore: GroceryStore) => this.groceryStoreService.deleteGroceryStore(groceryStore))
                this.groceryStoreOwnerService.getGroceryStoreOwner(groceryStoreOwnerSummary)
                    .flatMap((groceryStoreOwner: GroceryStoreOwner) => this.groceryStoreOwnerService.deleteGroceryStoreOnwer(groceryStoreOwner))
            }))
        .subscribe(() => {
            console.log("deleted grocery store")
            console.log("deleted grocery store owner")
        })
};

Answer 1

您可以通过嵌套运算符而不是链接它们来实现此目的。

这是一个不起作用的简化示例：

const teamSummary = userId
  .flatMap(userId  => getUser(userId))
  .flatMap(user    => getManager(user.managerId))
  .flatMap(manager => getDirectReports(manager.id))
  .map(reports     => buildSummary(user, manager, reports)) 
;                  // cannot find name 'user' / 'manager'

当我们嵌套运算符时，所有参数都可以在 map 内访问：

const teamSummary = userId
  .flatMap(userId => getUser(userId)
    .flatMap(user => getManager(user.managerId)
      .flatMap(manager => getDirectReports(manager.id)
        .map(reports => buildSummary(user, manager, reports))
      )
    )
  );

FWIW，这里有一些 StackBlitz