RxJS 6获取Observable数组的过滤列表

Question

在我的ThreadService类中，我有一个函数getThreads()，它向我返回Observable<Thread[]>所有线程。

现在，我想拥有另一个版本的函数，其线程由选定的主题过滤：function getSelectedThemeThreads(theme: Theme)。

我尝试了与运算符map，filter但是出现以下错误消息Property 'theme' does not exist on type 'Thread[]。

在我正在处理的代码下面：

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Observable, of } from 'rxjs';
import { catchError } from 'rxjs/operators';
import { Thread } from '../models/thread.model';
import { Theme } from '../models/theme.model';

@Injectable({
  providedIn: 'root'
})
export class ThreadService {
  private threadsUrl = 'api/threads';

constructor(private http: HttpClient) { }

getThreads(): Observable<Thread[]> {
  return this.http.get<Thread[]>(this.threadsUrl);
}

getSelectedThemeThreads(): Observable<Thread[]> {
  return this.http.get<Thread[]>(this.threadsUrl).pipe(
    map(threads => threads),
    filter(thread => thread.theme.id === theme.id)
  );
}

在此先感谢您的帮助。

Answer 1

我以这个StackBlitz为例/ angular6-filter-result

主要思想是进行过滤，map()因为过滤器将获得对象数组。

getSelectedThemeThreads(theme: string): Observable<Flower[]> {
    return this.http.get<Flower[]>(this.threadsUrl).pipe(
      map(result =>
        result.filter(one => one.theme === theme)
      )
    )
  }