错误TypeError:无法读取Object.eval上未定义的属性'_id'[作为updateDirectives]

时间:2018-11-02 16:55:20

标签: angular angular-ngmodel

im在数据绑定_id属性后得到此错误。谁能帮助我。

代码:

<div class="form-group">
  <input type="hidden" name="_id" #_id="ngModel" [(ngModel)]="iphoneService.selectedIphone._id">
</div>

这是iphone服务代码

import { Injectable } from "@angular/core";
import { HttpClient } from "@angular/common/http";
import { Observable } from "rxjs/Observable";
import "rxjs/add/operator/map";
import "rxjs/add/operator/toPromise";

import { Iphone } from "./iphone.model";

@Injectable()
export class IphoneService {
  selectedIphone: Iphone;
  iphones: Iphone[];
  readonly baseUrl = "http://localhost:3000/iphone";

  constructor(private http: HttpClient) {}

  postIphone(iphon: Iphone) {
    return this.http.post(this.baseUrl, iphon);
  }
}

iphon.model在这里

export interface Iphone {
_id: string;
firstName: string;
lastName: string;
email: string;
colorPrefence: string;
contact: string;
country: string;
state: string;
city: string;
zipCode: string;
transactionId: string;
__v: string;

}

这是iphone.component.ts

@Component({
selector: "app-iphone",
templateUrl: "./iphone.component.html",
styleUrls: ["./iphone.component.css"],
providers: [IphoneService]
})
export class IphoneComponent implements OnInit, AfterViewChecked {
constructor(public iphoneService: IphoneService) {}

ngOnInit() {}

onSubmit(form: NgForm) {
this.iphoneService.postIphone(form.value).subscribe(res => {});

}

我认为我收到的错误是由于模型的绑定不正确造成的,但是我无法弄清楚如何解决它。

1 个答案:

答案 0 :(得分:0)

在设计工作流程时遇到一些问题。

首先,您尝试绑定到服务中而不是组件中存在的变量。服务不应负责存储视图状态。视图状态应由组件负责。您需要在组件上有一个变量(例如selectedIphoneId),然后可以在[(ngModel)]中使用该变量。

还删除模板引用#_id=“ngModel的分配。如果您甚至不需要使用它,请摆脱它。您会有类似这样的内容:

<div class="form-group">
    <input type="hidden" name="_id" #_id [(ngModel)]="selectedIphoneId">
  </div>