在Angular视图中显示异步数据。

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英文:

display async data in the angular view

问题

我正在从API后端获取数据,并在Angular中将其内容显示在我的视图中,

对于服务,我正在使用可观察对象

export class PropertyService {
  apiUrl: string = environment.domain;

  constructor(private http: HttpClient) {}

  private _propertyDetailedInfo = new Subject();
  propertyDetailedInfo$: any = this._propertyDetailedInfo.asObservable();
  updatePropertyDetailedInfo(data: any) {
    this._propertyDetailedInfo.next(data);
    this.propertyDetailedInfo$ = data;
  }

  gerPropertyDetailedInfo(id: string) {
    const res = this.http.get(`${this.apiUrl}/property?id=${id}`);
    res.subscribe((val) => {
      this.updatePropertyDetailedInfo(val);
      console.log(this.propertyDetailedInfo$);
    });
  }
}

我在组件中订阅它

export class PropertySpecsComponent implements OnInit {
  propertyInfo!: any; 
  constructor(private propertyService: PropertyService) {}
  ngOnInit() {
    this.propertyService.gerPropertyDetailedInfo('90949d476fb');
    this.propertyService.propertyDetailedInfo$.subscribe((res: any) => {
      this.propertyInfo = res;
      console.log(
        ` flexibleCancellation : ${this.propertyInfo.flexibleCancellation}`
      );
    });
  }
}

console.log可以工作并显示我正在寻找的内容,甚至可以通过管道显示在视图中,我正在得到TRUE的值,但是在ng-for中无法读取它

在Angular视图中显示异步数据。

它的代码是

在Angular视图中显示异步数据。

我得到的错误是

在Angular视图中显示异步数据。

我尝试将数据对象静态地插入并将其存储在服务中(我没有使用可观察对象),可以通过json管道显示数据,也可以工作{{ propertyInfo.flexibleCancellation | json }},但对于*ngIf="propertyInfo.flexibleCancellation"不起作用

对我来说,async管道不起作用

*ngIf="propertyInfo.flexibleCancellation | async" 我得到:

在Angular视图中显示异步数据。

英文:

i am fetching the data form an API beck-end and displaying its content in to my view in angular,

for the service i am using observables

export class PropertyService {
  apiUrl: string = environment.domain;

  constructor(private http: HttpClient) {}

  private _propertyDetailedInfo = new Subject();
  propertyDetailedInfo$: any = this._propertyDetailedInfo.asObservable();
  updatePropertyDetailedInfo(data: any) {
    this._propertyDetailedInfo.next(data);
    this.propertyDetailedInfo$ = data;
  }


  gerPropertyDetailedInfo(id: string) {
    const res = this.http.get(`${this.apiUrl}/property?id=${id}`);
    res.subscribe((val) => {
      this.updatePropertyDetailedInfo(val);
      console.log(this.propertyDetailedInfo$);
    });
  }
}

and i am subscribing to it in the Component

export class PropertySpecsComponent implements OnInit {
  propertyInfo!: any; 
  constructor(private propertyService: PropertyService) {}
  ngOnInit() {
    
    this.propertyService.gerPropertyDetailedInfo('90949d476fb');
    this.propertyService.propertyDetailedInfo$.subscribe((res: any) => {
      this.propertyInfo = res;
      console.log(
        ` flexibleCancellation : ${this.propertyInfo.flexibleCancellation}`
      );
    });
  }
}

the console.log works and displays what i am looking and even can be displayed in the view with the pipe i am getting the value of TRUE for but is cant red the in ng-for

在Angular视图中显示异步数据。

the code for it:

在Angular视图中显示异步数据。

error i am getting:

在Angular视图中显示异步数据。

i trayed to insert the data-object staticly and stored it in service (i did not use observebols) that works displaying the data using json pipe aslo works {{ propertyInfo.flexibleCancellation | json }}

but not for *ngIf="propertyInfo.flexibleCancellation"

using aysinc pipe dos not work for me

*ngIf="propertyInfo.flexibleCancellation | async" i get: 

在Angular视图中显示异步数据。

答案1

得分: 1

使用可选链接是一种解决方案,无需使用异步管道

*ngIf="propertyInfo?.flexibleCancellation"

英文:

using optional chaining is a solution no need to use async pipe

*ngIf="propertyInfo?.flexibleCancellation" 

答案2

得分: 1

问题分析

可能是在可观察对象的响应被发出之前,您的组件视图已经被渲染。那时,属性 propertyInfo 是未定义的,因为它没有初始值。在您的模板中,对 propertyInfo 调用 flexibleCancellation 会导致 JavaScript 错误,因为 propertyInfo 还没有定义。

可能的解决方案:

1- 使用可选链,就像ibrahimgb的回答中那样

*ngIf="propertyInfo?.flexibleCancellation"

2- 将依赖于 propertyInfo 的模板部分包装在 *ngIf

<ng-container *ngIf=&quot;propertyInfo&quot;>
...
</ng-container>

如果属性未定义,则显示加载旋转器

3- 将空对象设置为 propertyInfo 的初始值

propertyInfo: any = {};
英文:

Problem Analysis

Probably the view of your component is rendered before the response of the observable is emitted. At that time the proprerty propertyInfo is undefined as it does not have an initial value. In your template the call of flexibleCancellation on propertyInfo leads to a javascript error, becasue propertyInfo is not yet defined.

Possible Solutions:

1- Use optional Chaining like in ibrahimgb's answer

*ngIf=&quot;propertyInfo?.flexibleCancellation&quot;

2- Wrap the part of the template that depends on propertyInfo in an *ngIf

&lt;ng-container *ngIf=&quot;propertyInfo&quot;&gt;
...
&lt;/ng-container&gt;

And display a loading spinner if the property is undefined

3- Set an empty object as initial Value for propertyInfo

propertyInfo: any = {};

答案3

得分: 1

视图在设置您的 propertyInfo 变量的值之前已开始渲染。使用 *ngIf 检查该值是否未定义可能会解决该问题。

英文:

The view is getting rendered before the value of your propertyInfo variable is set. Checking whether that value is undefined using *ngIf will solve the issue hopefully.

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  • 本文由 发表于 2023年6月14日 23:26:44
  • 转载请务必保留本文链接:https://go.coder-hub.com/76475201.html
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