Angular:'找不到'object'类型的不同支持对象'[object Object]'.NgFor 仅支持绑定到 Iterables，例如 Arrays' [英] Angular: 'Cannot find a differ supporting object '[object Object]' of type 'object'. NgFor only supports binding to Iterables such as Arrays'

问题描述

我创建了一个 angular 应用程序，它从一个 json 文件中获取数据.但是我在以 html 显示数据时遇到问题.很多变量都是荷兰语，我很抱歉.我对这一切也有点陌生:)

I've created an angular app which gets data from a json file. But I'm having issues with showing the data in html. A lot of variables are in dutch, I'm sorry for that. I'm also a bit new to all of this :)

这是我的服务:

import {Injectable} from '@angular/core';
import {Http, RequestOptions, Response, Headers} from '@angular/http';
import {Observable} from "rxjs";
import {Afdelingen} from "./models";

@Injectable()
export class AfdelingService {
  private afdelingenUrl = '/assets/backend/afdelingen.json';
    constructor(private http: Http) {
      }

      getAfdelingen(): Observable<Afdelingen[]> {
        return this.http.get(this.afdelingenUrl)
          .map(this.extractData)
          .catch(this.handleError);
      }

      private extractData(res: Response) {
        let body = <Afdelingen[]>res.json();
        return body || {};
      }

      private handleError(error: any): Promise<any> {
        console.error('An error occurred', error);
        return Promise.reject(error.message || error);
      }

      addAfdeling(afdelingsNaam: string, afdeling: any): Observable<Afdelingen> {
        let body = JSON.stringify({"afdelingsNaam": afdelingsNaam, afdeling: afdeling});
        let headers = new Headers({'Content-Type': 'application/json'});
        let options = new RequestOptions({headers: headers});
        return this.http.post(this.afdelingenUrl, body, options)
          .map(res => <Afdelingen> res.json())
          .catch(this.handleError)
      }
    }

这是我的 json 文件的一部分:

This is part of my json file:

{
  "afdelingen": [
    {
      "afdelingsNaam": "pediatrie",
      "kamernummer": 3.054,
      "patientid": 10001,
      "patientennaam": "Joske Vermeulen",
      "reden": "Appendicitis",
      "opname": "12/05/2017",
      "ontslag": "28/06/2017",
      "behandelingstype": "nazorg",
      "behandelingsomschrijving": "wondverzorging",
      "behandelingsdatum": "10/06/2017",
      "behandelingstijd": "10:20",
      "vegitarisch": false,
      "Opmerkingen": "",
      "sanitair": true,
      "kinderverzorgingsruimte": false,
      "salon": true,
      "hulp": true,
      "width": 5,
      "height": 5
    },
    {
      "afdelingsNaam": "pediatrie",
      "kamernummer": 3.055,
      "patientid": 10002,
      "patientennaam": "Agnes Vermeiren",
      "reden": "Beenbreuk",
      "opname": "18/05/2017",
      "ontslag": "30/06/2017",
      "behandelingstype": "nazorg",
      "behandelingsomschrijving": "wondverzorging",
      "behandelingsdatum": "10/06/2017",
      "behandelingstijd": "10:20",
      "vegitarisch": true,
      "Opmerkingen": "",
      "sanitair": true,
      "kinderverzorgingsruimte": false,
      "salon": true,
      "hulp": false,
      "width": 5,
      "height": 5
    }]}

组件:

import {Component, OnInit, Input} from '@angular/core';
import {Afdelingen} from "../models";
import {AfdelingService} from "../afdeling.service";
import {PatientService} from "../patient.service";


@Component({
  selector: 'app-afdeling',
  templateUrl: './afdeling.component.html',
  styleUrls: ['./afdeling.component.css']
})
export class AfdelingComponent implements OnInit {

 afdeling: Afdelingen[];
 errorMessage:string;

  constructor(private afdelingService: AfdelingService, private patientService: PatientService) { }

  ngOnInit() {
    this.getData()
  }

  getData() {
    this.afdelingService.getAfdelingen()
      .subscribe(
        data => {
          this.afdeling = data;
          console.log(this.afdeling);
        }, error => this.errorMessage = <any> error);

  }
}

和 html:

<ul>
  <li *ngFor="let afd of afdeling">
    {{afd.patientid}}
  </li>
</ul>

推荐答案

如报错信息所述，ngFor只支持Array等可迭代对象，所以不能使用对于 Object.

As the error messages stated, ngFor only supports Iterables such as Array, so you cannot use it for Object.

改变

private extractData(res: Response) {
  let body = <Afdelingen[]>res.json();
  return body || {};       // here you are return an object
}

到

private extractData(res: Response) {
  let body = <Afdelingen[]>res.json().afdelingen;    // return array from json file
  return body || [];     // also return empty array if there is no data
}

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