Question

为什么我收到此错误 无法设置未定义的属性“标题” 这是我的代码 https://stackblitz.com/edit/angular-pkd3qr?file=src%2Fapp%2Fapp.component.ts

import { Component } from '@angular/core';


interface DropDownModel {
  displayName: string;
  value: string;
}

interface DropdownModelWithtitle {
  title: string;
  dropDownOptions: DropDownModel[];
}

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
})
export class AppComponent  {
  name = 'Angular';
  typeOfProofObj: DropdownModelWithtitle;
  constructor(){
    this.typeOfProofObj.title = "ss";
    this.typeOfProofObj.dropDownOptions = [{displayName:'ss',value:'sss'}];

  }

}

我正在尝试将值插入变量中，那么如何解决此问题？

Answer 1

您需要先初始化typeOfProofObj变量，然后尝试访问其属性。

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
})
export class AppComponent  {
  name = 'Angular';
  typeOfProofObj: DropdownModelWithtitle = { title: null, dropDownOptions: null };

  constructor() {
     this.typeOfProofObj.title = "ss";
     this.typeOfProofObj.dropDownOptions = [ {displayName: 'ss', value: 'sss'} ];    
  }

}

Answer 2

您可以将DropdownModelWithTitle从接口更改为类，并将typeOfProofObj设置为新的DropdownModelWithTitle（）

interface DropDownModel {
  displayName: string;
  value: string;
 }

 class DropdownModelWithtitle {
  title: string;
  dropDownOptions: DropDownModel[];
 }

 @Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
  })
 export class AppComponent  {
   name = 'Angular';
   typeOfProofObj = new DropdownModelWithtitle();
   constructor(){
     this.typeOfProofObj.title = "ss";
     this.typeOfProofObj.dropDownOptions = [{displayName:'ss',value:'sss'}];

 }

}

Answer 3

另外，如果您对具有太多属性的变量有疑问，并且通过名称访问所有属性并不重要，则可以使用

typeOfProofObj : any = {}

无法在角度6中设置未定义的属性“标题”

3 个答案: