在整个长管道中传递/保持值的理智方法 [英] sane way to pass/keep a value throughout a long pipe

问题描述

假设我有以下 rxjs 管道:

Assuming i have the following rxjs pipe:

start$.pip(
    map((id)=> {}), //I want to save the "id" value to be used in the end of the pipe
    map(...),
    switchMap(...),
    map(...),
    switchMap(...),
    map(...),
    switchMap(...),
    switchMap(...)//I need the original "id" value here
).subscribe()

有没有办法在整个 pip 中保留id"值，以便它可以在管道的末端使用?

Is there a way to keep the 'id" value throughout the pip so it can be used at the end of the pipe?

动机:经常出现在 NGRX 效果中，我想使用触发源操作的原始负载数据来生成新操作.

Motivation: It comes often in NGRX effects where i want to use the original payload data of the triggering source action for generating the new action.

推荐答案

我认为正确的做法是再做一次闭包

I think the correct way is to make another closure

const processId = (id) => observableOf(id)
  .pipe(
    map(() => { ... }),
    map(...),
    switchMap(...),
    map(...),
    switchMap(...),
    map(...),
    switchMap(...),
    switchMap(...) // Use id here
  );

const getPipe = () => start$
  .pipe(switchMap(processId));

在 getPipe 中存储局部变量作为副作用是可以的，但如果 start$ Observable 发出更多值，它可能会中断.

Storing local variable as a side effect in getPipe is OK, but it can break if start$ Observable emits more values.

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