Angular2中带有rxjs映射的嵌套http请求

我是Rxjs的新手（一般来说是Angular2），我很难理解Rxjs的精妙之处

我想对GitLab API进行两个REST调用：

接收某个用户的所有组（通过gitlab.com/api/v4/groups）。这将返回一个JSON，如下所示：

[ { "id": 1511397, "name": "some name", "parent_id": 1505403, ... }, { "id": 1511403, "name": "some other name", "parent_id": 1505403, ... } ]

因此，基本上我需要遍历第一个请求提供的所有ID，并提供一组组详细信息：

[
 {
 "id": 1511397,
 "name": "group name",
 "parent_id": 1505403,
 "projects": [
     {
         "id": 3099499,
         "description": "project 1"
     },
     {
         "id": 3099489,
         "description": "Project 2"
     }
 ]
 },
 {
 "id": 1194997,
 "name": "a second group name",
 "parent_id": 152393,
 "projects": [
     {
         "id": 9423423,
         "description": "project 3"
     },
     {
         "id": 2394238,
         "description": "Project 4"
     }
 ]
 }
]

---

如何做到这一点？我已经尝试过switchMap、concatMap和MergeMap，但我从来都无法让它工作……

类似的东西。您需要将static Observable.of替换为$http observables

Rx.Observable.of([{userId:1}, {userId:2}])
.switchMap(ids => Rx.Observable.of(...ids))
.mergeMap(userId => {
 return Rx.Observable.of([
   {userId:userId, name:'project1'},
   {userId:userId, name:'project2'}
 ]);
})
.subscribe(x=>console.log(x));

of（[{userId:1}，{userId:2}]）类似于http调用，它给出了u个用户数组 2.switchMap（ids=>Rx.Observable.of（…ids））-为每个用户创建一个单独的Observable

.mergeMap用于调用$http以获取项目的每个可观察用户

---

你可以这样做

getGroups() {
  return this.http.get('gitlab.com/api/v4/groups')
    .map(res => res.json()) // convert to object[]
    .map(res => res.map(g => g.id)) // get all id
    .mergeMap(gid => {
      let gs = [];
      gid.forEach(id => {
        let req = this.http.get(`gitlab.com/api/v4/groups/${id}`);
        gs.push(req);
      });
      return Observable.forkJoin(gs);
    })
    .map(res => { // we have array of Response Object
        return res.map(x => x.json()); // Array.map not Observable map operator.
    });
}

getGroups().subscribe(res => console.log(res))

getGroups() {
  return this.http.get('gitlab.com/api/v4/groups')
    .map(res => res.json()) // convert to object[]
    .map(res => res.map(g => g.id)) // get all id
    .mergeMap(gid => {
      let gs = [];
      gid.forEach(id => {
        let req = this.http.get(`gitlab.com/api/v4/groups/${id}`);
        gs.push(req);
      });
      return Observable.forkJoin(gs);
    })
    .map(res => { // we have array of Response Object
        return res.map(x => x.json()); // Array.map not Observable map operator.
    });
}

getGroups().subscribe(res => console.log(res))