javascript - 将多个可观察数组组合成新的对象数组

Question

我有 3 个如下所示的可观察数组。

persons = [
   {
      "firstName":"john",
      "lastName":"public",
      "locationID":"1",
      "departmentID":"100"
   },
   {
      "firstName":"sam",
      "lastName":"smith",
      "locationID":"2",
      "departmentID":"101"
   }
]

departments = [{"departmentID": "100",
               "name": "development"
               },
               {"departmentID": "101",
                "name": "sales"
               }]

locations = [{"locationID": "1", "name": "chicago"},
              {"locationID":"2", "name": "ny"}]

我正在尝试将这 3 个组合成下面的结果，

result = [
   {
      "firstName":"john",
      "lastName":"public",
      "location":"development",
      "department":"sales"
   },
   {
      "firstName":"sam",
      "lastName":"smith",
      "location":"ny",
      "department":"sales"
   }
]

为了获得预期的结果，我在 persons observable 上使用了 map 函数来提供新的对象数组。

this.store<Person>('persons')
.map(function(person){
     let p = new personDetail()
     p.firstName = person.firstName,
     p.lastName = person.lastName
     return p;
})

PersonDetail 对象具有 firstName、lastName、location 和 department 属性。如何查找可观察的部门并获取 departmentID 的匹配行以获取部门名称？

我是 rxjs 库的新手，请告诉我是否有更好的方法来达到预期的结果。

Answer 1

因为您很可能希望从远程服务获取部门和位置列表(发出另一个 HTTP 请求)，所以我也会立即使用 Observables 来完成。

Observable.from(persons)
    .mergeMap(person => {
        let department$ = Observable.from(departments)
            .filter(department => department.departmentID == person.departmentID);

        let location$ = Observable.from(locations)
            .filter(location => location.locationID == person.locationID);

        return Observable.forkJoin(department$, location$, (department, location) => {
            return {
                'firstName': person.firstName,
                'lastName': person.lastName,
                'location': location.name,
                'department': department.name,
            };
        });
    })
    .toArray()
    .subscribe(result => console.log(result));

这会打印到控制台:

[ { firstName: 'john',
    lastName: 'public',
    location: 'chicago',
    department: 'development' },
  { firstName: 'sam',
    lastName: 'smith',
    location: 'ny',
    department: 'sales' } ]

有两个 Observables department$ 和 location$ 被 filter() 运算符过滤以获得唯一具有匹配 ID 的项目.那么forkJoin()运算符(operator)等待直到它们都完成。运算符 mergeMap() 然后重新发出从 forkJoin() 返回的值。在 toArray() 的最后，我们将所有项目收集到一个数组中。

代替Observable.from(...)，您可以获得您需要的任何服务(例如http.get(...))。

查看现场演示:https://jsbin.com/nenekup/4/edit?js,console

类似问题:Merge subarrays using Observables和 Subscribing to a nested Observable