Angular 6 管道 RxJs 操作符链接 3 个依赖的 observables [英] Angular 6 pipe RxJs operator to chain 3 dependant observables

问题描述

我有 3 个依赖的 Rest API 资源(比如 observables)，如下所示:

I have 3 dependent Rest API resources (lets say observables) like this:

第一个 observable 将一个项目作为用户数组生成，如下所示:

1st observable produces one item as array of users, like this:

getUsers(): Observable<User[]>
    [
      {
        "id": 1,
        "name": "Peter",
        "surname": "Smith"
      },
      {
        "id": 2,
        "name": "John",
        "surname": "Wayne"
      },
      ...
    ]

2nd observable 可用于获取分配给用户的地址，因此输入参数为用户 ID，并以地址数组的形式返回一项:

2nd observable can be used to fetch addresses assigned to user, so the input parameter is User ID, and returns a one item as array of addresses:

getUserAddresses(user_id: string): Observable<Address[]>
    [
      {
        "id": 1,
        "city": "London",
        "street": "Wicombe 34"
      },
      {
        "id": 2,
        "city": "Paris",
        "street": "La fever 20"
      },
      ...
    ]

3rd observable 可用于获取分配给用户的公司，因此输入参数为用户 ID，并以公司数组形式返回一项:

3rd observable can be used to fetch companies assigned to user, so the input parameter is User ID, and returns a one item as array of companies:

getUserCompanies(user_id: string): Observable<Company[]>
    [
      {
        "id": 1,
        "name": "Fintch CO",
        "state": "France"
      },
      {
        "id": 2,
        "name": "C&C inc.",
        "state": "USA"
      },
      ...
    ]

<小时>

我想将这 3 个 observable 链接成一个，它将再次作为一个项目产生结果，其中将包含用户数组及其附加地址数组和公司数组，如下所示:

---

I want to chain these 3 observables into one which will produce the result again as one item, that will contain array of users with their additional addresses arrays and companies array, like following:

    [
      {
        "id": 1,
        "name": "Peter",
        "surname": "Smith",
        "addreesses": 
               [
                 {
                   "id": "1",
                   "city": "London",
                   "street": "Wicombe 34"
                 },
                 {
                   "id": "2",
                   "city": "",
                   "street": "La fever 20"
                 }
               ],
        "companies": 
               [
                 {
                   "id": "1",
                   "name": "Fintch CO",
                   "state": "France"
                 },
                 {
                   "id": "2",
                   "name": "C&C inc.",
                   "state": "USA"
                 }
               ]
        }
      },
      {
        "id": 2,
        "name": "John",
        "surname": "Wayne",
        "addresses": [...],
        "companies": [...],
      },
      ...
    ]

在带有 RxJs 6 的 Angular 6 中，操作符应该如何组合来实现这一点?非常感谢您的建议.

How should look like the operators composite to achieve that in Angular 6 with RxJs 6? Thanks a lot for advice.

推荐答案

这样的事情可以工作

getUsers()
.pipe(
  switchMap(users => from(users)),
  mergeMap(user => forkJoin(getAddresses(user.id), getCompanies(user.id))
                   .pipe(map(data => ({user, addresses: data[0], companies: data[1] })))
  tap(data => data.user.addresses = data.addresses),
  tap(data => data.user.companies = data.companies),
  map(data => data.user),
  toArray()
  )
)

应用于不同用例的类似链在这里有更详细的解释.

Applied to a different use case a similar chain is explained in more details here.

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