Exploring techniques for looping through JSON response data in Angular 2 using TypeScript

Question

Exploring techniques for looping through JSON response data in Angular 2 using TypeScript

When I receive this JSON data as a response, I attempt to iterate through it inside the "component template attribute" in order to display the content within an "li" tag HTML.

{
  "items": [
    {
      "aliases": [
        "http://www.xyz.co",
        "http://facebook.xyz.co"
      ],
      "styling": {
        "tag_background_color": "#E0EAF1",
        "tag_foreground_color": "#3E6D8E",
        "link_color": "#0077CC"
      },
      "related_sites": [
        {
          "relation": "meta",
          "api_site_parameter": "meta.xyz",
          "site_url": "http://meta.xyz.co",
          "name": "Meta Stack Overflow"
        },
        {
          "relation": "chat",
          "site_url": "http://chat.xyz.co",
          "name": "Stack Overflow Chat"
        }
      ],
      "markdown_extensions": [
        "Prettify"
      ],
      "launch_date": 1221436800,
      "closed_beta_date": 1217462400,
      "site_state": "normal",
      "high_resolution_icon_url": "https://cdn.sstatic.net/Sites/sxyz/img/<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="92f3e2e2fef7bfe6fde7f1fabffbf1fdfcd2a0bce2fcf5">[email protected]</a>",
      "favicon_url": "https://cdn.sstatic.net/Sites/stackoverflow/img/favicon.ico",
      "icon_url": "https://cdn.sstatic.net/Sites/xyz/img/apple-touch-icon.png",
      "audience": "professional and enthusiast programmers",
      "site_url": "http://xyz.co",
      "api_site_parameter": "xyz",
      "logo_url": "https://cdn.sstatic.net/Sites/stackoverflow/img/logo.png",
      "name": "Stack Overflow",
      "site_type": "main_site"
    },
    {
      "aliases": [
        "http://www.xyz.co",
        "http://facebook.xyzw.co"
      ],
      "styling": {
        "tag_background_color": "#E0EAF1",
        "tag_foreground_color": "#3E6D8E",
        "link_color": "#0077CC"
      },
      "related_sites": [
        {
          "relation": "meta",
          "api_site_parameter": "meta.xyz",
          "site_url": "http://meta.xyz.co",
          "name": "Meta Stack Overflow"
        },
        {
          "relation": "chat",
          "site_url": "http://chat.xyz",
          "name": "Stack Overflow Chat"
        }
      ],
      "markdown_extensions": [
        "Prettify"
      ],
      "launch_date": 1221436800,
      "closed_beta_date": 1217462400,
      "site_state": "normal",
      "high_resolution_icon_url": "https://cdn.sstatic.net/Sites/xyz/img/<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="f8998888949dd58c978d9b90d5919b9796b8cad688969f">[email protected]</a>",
      "favicon_url": "https://cdn.sstatic.net/Sites/sxyz/img/favicon.ico",
      "icon_url": "https://cdn.sstatic.net/Sites/xyz/img/apple-touch-icon.png",
      "audience": "professional and enthusiast programmers",
      "site_url": "http://stackoverflow.co",
      "api_site_parameter": "stackoverflow",
      "logo_url": "https://cdn.sstatic.net/Sites/xyzw/img/logo.png",
      "name": "Stack Overflow",
      "site_type": "main_site"
    }
  ]
}

The JS code snippet is provided below:

@Component({
    selector: 'http-test',
    template: ` 
       <ul>    
          <li *ngFor="#data of httpData>{{data.items.related_sites[0].name}}  //attempting to iterate through the response data.
          </li>
       </ul>
     `,
     providers:[HTTPTestService]

})


export class HTTPTestComponent {
    public httpData;

    constructor (private _httpService: HTTPTestService){}

    getStack(){
      this._httpService.getItemData()
          .subscribe(             
             data =>this.httpData = JSON.stringify(data),
             error => alert(error),
             () =>console.log("finished")
          );
    }
    ngOnInit() {
      this.getStack();
    }
 }

I've made attempts but have been unable to achieve my desired outcome. Any assistance would be greatly appreciated. Thank you.

angular typescript

Answer 1

Answer №1

Give this a shot

  <li *ngFor="let item of serverResponse.items>{{item.related_sites[0].name}}  //testing the iteration of server response data.
  </li>

Answer 2

Give this a shot

  <li *ngFor="let item of serverResponse.items>{{item.related_sites[0].name}}  //testing the iteration of server response data.
  </li>

Answer 3

Answer №2

Check out the code snippet below:

<ul class="menu">
  <li *ngFor="let item of httpData.items>
    <ul>
      <li *ngFor="let alias of item.aliases>
        {{alias}}</br>
      </li>
    </ul> 
    ..
    <ul>
      <li *ngFor="let related_site of item.related_sites>
        {{relation}}
        {{api_site_parameter}}
        {{site_url}}
        {{name}}
      </li>
    </ul>
     ..
     ..
  </li>
</ul>

Answer 4

Check out the code snippet below:

<ul class="menu">
  <li *ngFor="let item of httpData.items>
    <ul>
      <li *ngFor="let alias of item.aliases>
        {{alias}}</br>
      </li>
    </ul> 
    ..
    <ul>
      <li *ngFor="let related_site of item.related_sites>
        {{relation}}
        {{api_site_parameter}}
        {{site_url}}
        {{name}}
      </li>
    </ul>
     ..
     ..
  </li>
</ul>

Answer 5

Answer №3

One issue that stands out is within the getStack() function, specifically where you subscribe to the http response observer. There seems to be a conversion error as you are converting the response to a string using JSON.stringify(data). It's important to have an object instead of just its JSON string form so that you can easily access its properties in your template.

The code snippet for the HTTPTestService class was not provided, which leaves uncertainty about whether any post-processing, such as a .map(...) call, is done on the response before passing it to the subscriber(s). If you are returning the original Observable<Response> to the subscriber, then you will need to parse the response body into a valid object. You can achieve this by replacing the following line:

data =>this.httpData = JSON.stringify(data)

with

data => this.httpData = data.json()

It's advisable to handle this conversion in your service file, ensuring that it already returns a valid object to your component. Additionally, remember to place the parsing call within a try-catch block to handle scenarios where the server sends back an invalid JSON response.

After resolving the issue with parsing the http response, you should be able to loop through your data according to the guidance provided by Amol Bhor in another related answer.

Answer 6

One issue that stands out is within the getStack() function, specifically where you subscribe to the http response observer. There seems to be a conversion error as you are converting the response to a string using JSON.stringify(data). It's important to have an object instead of just its JSON string form so that you can easily access its properties in your template.

The code snippet for the HTTPTestService class was not provided, which leaves uncertainty about whether any post-processing, such as a .map(...) call, is done on the response before passing it to the subscriber(s). If you are returning the original Observable<Response> to the subscriber, then you will need to parse the response body into a valid object. You can achieve this by replacing the following line:

data =>this.httpData = JSON.stringify(data)

with

data => this.httpData = data.json()

It's advisable to handle this conversion in your service file, ensuring that it already returns a valid object to your component. Additionally, remember to place the parsing call within a try-catch block to handle scenarios where the server sends back an invalid JSON response.

After resolving the issue with parsing the http response, you should be able to loop through your data according to the guidance provided by Amol Bhor in another related answer.

Exploring techniques for looping through JSON response data in Angular 2 using TypeScript

Answer №1

Answer №2

Answer №3

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