javascript - Angular 2主题不是函数

Question

尝试与 2 个组件通信我以为我可以进行 http 调用，然后可以对主题进行 mergeMap 或 switchMap？

有点像

import {Subject} from 'rxjs/Subject';

 constructor(private _http: HttpClient) {
    this.populateList = new Subject<Blog[]>();
 }

getBlogs(){
  return this._http.get(this.blogsURL+'blogs')
       .map((result: Response ) => {
       this.blogs = result['blogs'];
    return this.blogs;
  }).switchMap((blogs)=>this.populateList.next(blogs))
}

但是我得到:

You provided 'undefined' where a stream was expected. You can provide an Observable, Promise, Array

我在尝试订阅主题时遇到错误:

 this.blogsService.populateList()
      .subscribe((res)=>{
      console.log(res)
  })

this.blogsService.populateList is not a function

我正在寻找一种在 http 调用后更新 View 的方法

Answer 1

你需要像这样订阅不带()。因为它不是一个函数。惊喜

 this.blogsService.populateList.subscribe()

并像这样重写第一个函数，因为您不需要切换映射，您只需要做的就是填充列表的副作用。

getBlogs(){
  return this._http.get(this.blogsURL+'blogs')
       .map((result: Response ) => {
       this.blogs = result['blogs'];
    return this.blogs;
  }).do((blogs)=>this.populateList.next(blogs))
}