Question

如果控制台向我显示以下内容，如何解决subcribe（）对我的app.component的问题：错误TypeError：无法读取未定义的属性“ subscribe” 在AppComponent.push ../ src / app / app.component.ts.AppComponent.ngOnInit

数据服务：

   import { Injectable } from '@angular/core';
   import { Http, Response } from '@angular/http';

   import { Injectable } from '@angular/core';
   import { Observable, Subject, ReplaySubject } from 'rxjs';
   import { from, of, range } from 'rxjs/create';
   import { map, filter, switchMap } from 'rxjs/operators';


 @Injectable({
    providedIn: 'root'
    })


export class DataService {

  constructor(private http: Http) { }

  fetchData(){
    this.http.get('assets/ninjas.json').pipe(
     map((res) => return res.json()))}}

应用组件：

import { Component } from '@angular/core';
import { DataService } from './data.service';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})

export class AppComponent {
  title = 'app';
  ninjas = [];

  constructor(private newService: DataService){ }

  ngOnInit(){
   this.newService.fetchData().subscribe(
    (data) => this.ninjas = data;
   );
  }
 }

Answer 1

返回服务中的可观察物，

 fetchData(){
    return this.http.get('assets/ninjas.json').pipe(
     map((res) => return res.json()))}}

Answer 2

只需删除“管道”即可，您不需要它：

    let min = (a,b) => 
      if (a < b) {
        return a;
      }
      else if (b < a) {
        return b;
      }
      else {
        console.log("error");
      };

Angular Subscribe（）返回未定义

2 个答案: