在我的ThreadService类中,我有一个函数getThreads(),它返回一个Observable< Thread []>用我所有的线程.

现在,我希望我的函数的另一个版本,我的线程被选定的主题过滤：function getSelectedThemeThreads(theme：Theme).

我尝试使用运算符映射和过滤器但是我有以下错误消息属性’主题’在类型’Thread []上不存在.

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.

解决方法:

我举了一个这个StackBlitz / angular6-filter-result的例子

主要思想是在map()中过滤,因为过滤器将获得一个对象数组.

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