angular - 订阅不是函数错误

Question

我正在尝试订阅来自服务的可观察对象，它构建时没有错误，但在浏览器中查看时出现错误“this.service.getBanners(...).subscribe is not a function”。

服务:

import { Injectable } from '@angular/core';
import { Observable } from 'rxjs';

@Injectable()

export class BannerService {

    banners: any = ['1','2','3'];

    constructor(
    ) {}

    getBanners(): Observable<any[]> {
        return this.banners;
    }

    setBanners(banners: any[]): void {
        this.banners = banners;
    }

}

组件:

import { Component, ViewEncapsulation, OnInit } from '@angular/core';
import { Observable } from 'rxjs';
import { BannerService } from './../banner/banner.service';

@Component({
    selector: '.banner',
    templateUrl: './banner.component.html',
    styleUrls: ['./banner.component.sass'],
    encapsulation: ViewEncapsulation.None
})

export class BannerComponent implements OnInit {

    banners: any[];

    constructor(private bannerService: BannerService){

    }

    ngOnInit() {
        this.bannerService.getBanners().subscribe(banners => this.banners = banners);
    }
}

知道我做错了什么吗？

Answer 1

您应该返回一个 observable ，而不是返回一个数组:

对于 Angular <= 5.x.x

getBanners(): Observable<any[]> {
    return Observable.of(this.banners);
}

对于 Angular >= 6.x.x

getBanners(): Observable<any[]> {
    return of(this.banners);
}

Reference