角度2-无法读取带有上下文错误上下文的未定义错误的属性"0":[对象对象] [英] Angular 2 - Cannot read property '0' of undefined error with context ERROR CONTEXT: [object Object]

问题描述

我的服务就是这样

getRecords(): Observable<any>{
    return this.http.get(this.fetchAdminData)
                    .map(this.extractData)
                    .catch(this.handleError);
  }

，提取数据如下

private extractData(res: Response) {
    let body = res.json();
    return body || { };
  }

在我的组件中，我称其为

In my component i am calling this as follows

import {Component, OnInit} from '@angular/core'
import {FormsHandler} from '../services/service.forms'


@Component({
  selector: 'form-admin',
  templateUrl: '../partials/form5.html'
})

export class FormAdminComponent implements OnInit {
  public records
  constructor(private formHandler : FormsHandler){
  }

  ngOnInit(){
    this.formHandler.getRecords().subscribe(res => {
      if (res.ok){
        this.records = res.data
        console.log(res)
        console.log(this.records[0])
      }
    })
  }

}

但是在html中按如下所示调用它时会出错

But when this is called on as follows in html it errors

{{records}} // this is working perfectly 
    {{records[0]}}  //Cannot read property '0' of undefined ERROR CONTEXT:    [object Object]

我什至无法访问这样的嵌套对象

also i even cannot access my nested object like this

<tr *ngFor="let record of records">
              <td>{{record.firstName + " "+ record.middleName+ " "+ record.LastName}}</td>
              <td>{{record.BankingDetails.company}} </td> // This results in errorTypeError: Cannot read property 'company' of undefined
              <td>{{record.BankingDetails}} </td> //working fine but resulting in [object Object]

              <td>Pending</td>
              </td>
            </tr>

导致TypeError:无法读取未定义的属性"company"

results in TypeError: Cannot read property 'company' of undefined

我的回答是这样的

Object {ok: true, data: Array[2]}

完整的数据是这样的:

[
 {
"Address": {
"addressLine1":  "nh" ,
"addressLine2":  "nghn" ,
"city":  "ngh" ,
"formStatus": 2 ,
"pinCode":  "ngh" ,
"state":  "nghn"
} ,
"BankingDetails": {
"bankName":  "csdcss" ,
"company":  "cd" ,
"designation":  "kn" ,
"loanAmount":  "csd" ,
"loanPurpose":  "cs" ,
"panCardNumber":  "84894848" ,
"salary":  "55"
} ,
"contact":  "vsd" ,
"date":  "vsd" ,
"dob": Mon Jan 01 1 00:00:00 GMT+00:00 ,
"email": [e-mail], »
"firstName":  "cs" ,
"firstname":  "" ,
"formStatus": 3 ,
"gender":  "male" ,
"id":  "98fd72b9-62fe-4fcd-90d6-f2a5f83c052b" ,
"isAdmin": 1 ,
"lastName":  "vs" ,
"lastname":  "" ,
"middleName":  "vds" ,
"middlename":  "" ,
"month":  "vsd" ,
"password": <binary, 60 bytes, "24 32 61 24 31 30..."> ,
"username":  "" ,
"year":  "vs"
},
...
]

我没有做错什么，因为它可以在console.log上正常工作并打印一个json，但是无法通过html进行访问

i did't getting what am i doing wrong becuase its working fine with console.log and printing a json but is not accessible with html

我也注意到当我使用

{{records}} 

其产生[object Object]

its resulting in [object Object]

我必须明确地写

{{records | json}}

获取我的完整数据

嘿，请告诉我我在做什么错，我想访问我的嵌套元素，例如records.BankingDetails.company

Hey please suggest me what i am doing wrong i want to access my nested elements like records.BankingDetails.company

推荐答案

根据@Akshay Rao的建议，我终于找到了解决此问题的方法 我使用了这些，以便在呈现页面

I finally got a solution to this problem as per @Akshay Rao suggestions i used these so that data is available before rendering of page

<div *ngIf="records">
</div>

也按照@GünterZöchbauer的建议，我确实需要使用像(Elvis)这样的运算符

also as per @Günter Zöchbauer suggestion i do require to use (Elvis) operator like

{{record.BankingDetails?.company}}

，效果很好. 谢谢

这篇关于角度2-无法读取带有上下文错误上下文的未定义错误的属性"0":[对象对象]的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！