在订阅方法中构建父子对象

Question

我有一个 Angular 组件，它订阅了一个由 Angular 服务返回的可观察对象。

组件： help.component.ts

import { WikiService } from '../../../services/wiki.service';

import { WikiTree } from '../../../interfaces/WikiTree';

export class HelpComponent implements OnInit {

    wikiTree$: Observable<WikiTree>
    wikiChildTree$: Observable<WikiTree>

    public infoCards: Array<Object>;

    constructor(private wikiService: WikiService) {}

    ngOnInit() {
            this.wikiTree$ = this.wikiService.GetWikiHierarchy();
            this.wikiTree$.subscribe((data)=>{
            const newInfoCards = data.page.results.map(result => (
            {
              "image": "",
              "title": result.title,
              "titleLink": "/page/wiki/"+ result.id,
              "children": []  /*TODO: Populate this array with a Service call based on result.id*/
            }))
            this.infoCards = [...this.infoCards,...newInfoCards]
          },
          (err) => {
            console.log(err);
          }
       );
    }

wikiTree$ Observable 具有以下JSON，转换为 TypeScript：

{
    "page": {
        "results": [
            {
                "id": "123456789",
                "type": "page",
                "status": "current",
                "title": "Start here",
                "extensions": {
                    "position": 0
                },
                "_links": {
                    "webui": "/display/MYSPACE/Start+here",
                    "edit": "/pages/resumedraft.action?draftId=123456789",
                    "tinyui": "/x/BQD2Mw",
                    "self": "https://wiki.abc.com/rest/api/content/123456789"
                },
                "_expandable": {
                    "container": "/rest/api/space/MYSPACE",
                    "metadata": "",
                    "operations": "",
                    "children": "/rest/api/content/123456789/child",
                    "restrictions": "/rest/api/content/123456789/restriction/byOperation",
                    "history": "/rest/api/content/123456789/history",
                    "ancestors": "",
                    "body": "",
                    "version": "",
                    "descendants": "/rest/api/content/123456789/descendant",
                    "space": "/rest/api/space/MYSPACE"
                }
            },
            {
                "id": "567890123",
                "type": "page",
                "status": "current",
                "title": "FAQ",
                "extensions": {
                    "position": 1
                },
                "_links": {
                    "webui": "/display/MYSPACE/FAQ",
                    "edit": "/pages/resumedraft.action?draftId=567890123",
                    "tinyui": "/x/HQD2Mw",
                    "self": "https://wiki.abc.com/rest/api/content/567890123"
                },
                "_expandable": {
                    "container": "/rest/api/space/MYSPACE",
                    "metadata": "",
                    "operations": "",
                    "children": "/rest/api/content/567890123/child",
                    "restrictions": "/rest/api/content/567890123/restriction/byOperation",
                    "history": "/rest/api/content/567890123/history",
                    "ancestors": "",
                    "body": "",
                    "version": "",
                    "descendants": "/rest/api/content/567890123/descendant",
                    "space": "/rest/api/space/MYSPACE"
                }
            }
        ],
        "start": 0,
        "limit": 25,
        "size": 2,
        "_links": {
            "self": "https://wiki.abc.com/rest/api/content/998877665/child/page"
        }
    },
    "_links": {
        "base": "https://wiki.abc.com",
        "context": "",
        "self": "https://wiki.abc.com/rest/api/content/998877665/child"
    },
    "_expandable": {
        "attachment": "/rest/api/content/998877665/child/attachment",
        "comment": "/rest/api/content/998877665/child/comment"
    }
}

打字稿：WikiTree.ts

export interface WikiTree {
    page: Page;
    _links: Links;
    _expandable: Expandable;
  }
  export interface Page {
    results?: (ResultsEntity)[] | null;
    start: number;
    limit: number;
    size: number;
    _links: Links1;
  }
  export interface ResultsEntity {
    id: string;
    type: string;
    status: string;
    title: string;
    extensions: Extensions;
    _links: Links2;
    _expandable: Expandable1;
  }
  export interface Extensions {
    position: number;
  }
  export interface Links2 {
    webui: string;
    edit: string;
    tinyui: string;
    self: string;
  }
  export interface Expandable1 {
    container: string;
    metadata: string;
    operations: string;
    children: string;
    restrictions: string;
    history: string;
    ancestors: string;
    body: string;
    version: string;
    descendants: string;
    space: string;
  }
  export interface Links1 {
    self: string;
  }
  export interface Links {
    base: string;
    context: string;
    self: string;
  }
  export interface Expandable {
    attachment: string;
    comment: string;
  }

我想通过调用基于其父项的服务来填充 children 数组 result.id

例如：调用将是 Wiki 服务中的一个函数，returns 一个可观察对象。

this.wikiChildTree$ = this.wikiService.GetWikiHierarchy(result.id);

根据 wikiChildTree$ observable 中返回的数据，我想创建一个 title 和 link 对象的数组。因此，infoCards 对象数组将反映一个 JSON 对象，如下所示：

[{
        "image": "",
        "title": "Start here",
        "titleLink": "/page/wiki/123456789",
        "children": [{
            "title": "Storm",
            "link": "/page/wiki/660431"
        },
        {
            "title": "Weather",
            "link": "/page/wiki/660432"
        }]
},
{
        "image": "",
        "title": "FAQ",
        "titleLink": "/page/wiki/567890123",
        "children": [{
            "title": "Cloud",
            "link": "/page/wiki/450433"
        },
        {
            "title": "Sunshine",
            "link": "/page/wiki/120432"
        }]
}
]

这就像进行父子异步调用，以获取子数据。

我已经阅读了 forkjoin 和 mergemap，但不确定这里的实现。我怎么做？

Answer 1

所以基本上你应该可以这样做：

ngOnInit() {
       this.wikiTree$ = this.wikiService.GetWikiHierarchy().pipe(
          switchMap(data => 
             forkJoin(data.page.results.map(result => this.wikiService.GetWikiHierarchy(result.id))).pipe(
                map(children => ({data, children}))
             )
          )
       ).subscribe(({data, children}) => {
            const newInfoCards = data.page.results.map((result, i) => (
            {
              "image": "",
              "title": result.title,
              "titleLink": "/page/wiki/"+ result.id,
              "children": children[i]
            }))
            this.infoCards = [...this.infoCards,...newInfoCards]
          },
          (err) => {
            console.log(err);
          }
       );
}

说明：

你加载this.wikiService.GetWikiHierarchy();
您使用 同时为每个结果加载所有 this.wikiService.GetWikiHierarchy(result.id) forkJoin.
您将两个地方的加载数据映射到 object {data, children} where data - 第一次调用的结果 children - 第二个 forkJoin 的结果（children 或 child[][ 的数组]).
之后你需要加入 data.page.results 和 children（这是数组的数组） . 希望对您有所帮助。

Answer 2

向 Amir 的回答添加了 return 数据以消除错误。 map 函数需要 return 一个 wikiTree 类型的可观察对象。

ngOnInit() {
       this.wikiTree$ = this.wikiService.GetWikiHierarchy().pipe(
          switchMap(data => 
             forkJoin(data.page.results.map(result => this.wikiService.GetWikiHierarchy(result.id))).pipe(
                map(children => ({data, children}))
             )
          )
       ).subscribe((data, children) => {
            const newInfoCards = data.page.results.map((result, i) => (
            {
              "image": "",
              "title": result.title,
              "titleLink": "/page/wiki/"+ result.id,
              "children": children[i]
            }))
            this.infoCards = [...this.infoCards,...newInfoCards]
            return data
          },
          (err) => {
            console.log(err);
          }
       );
}

在订阅方法中构建父子对象

Building Parent Child object inside subscribe method

typescript

angular

angular5