How can I display the top 5 data results after subscribing in Nativescript?

Question

How can I display the top 5 data results after subscribing in Nativescript?

Utilizing this function allows me to retrieve all my data from the web service.

 public data: Data[];
    getall() {
        this.ws.getalldata().subscribe(
            data=> {
                this.data= data;
            }
        );
    }

Here is a snippet from the Json file:

 {
        "StatusCode": 0,
        "StatusMessage": "OK",
        "StatusDescription": [
            {
                "id": "1",
                "id_type": 1,
                "desc": "TRTY",
                "active": 0,
                },
              ....
             {
                "id": "3",
                "id_type": 50,
                "desc": "qqq",
                "active": 0,
            },
            {
                "id": "4",
                "id_type": 50,
                "desc": "qqq",
                "active": 0,
            },
               ......
           {
                "id": "30",
                "id_type": 2,
                "desc": "hhh",
                "active": 0,
            }
          }

To display this data in html, you can use the following code:

  <StackLayout *ngFor="let item of data">                
        <Label row="1" col="1" text="" class="list-group-item-text" [text]='item.id_type'></Label>
        <Label row="1" col="1" text="" class="list-group-item-text" [text]='item.desc'></Label>
     </StackLayout>

Now, I am looking for a way to display only the top 5 elements in the template. How can I achieve this?

angular typescript filter nativescript

Answer 1

Answer №1

According to the RxJs documentation, if you need to manipulate the 5 most recent items, you can achieve this in RxJs 6 with the following code:

import { concatAll, takeLast } from 'rxjs/operators';

public data: Data[] = [];
...

    this.ws.getalldata().pipe(concatAll(), takeLast(5)).subscribe(
        item=> {
            this.data.push(item);
        }
    );

Another way to accomplish this is by manipulating the array directly,

    this.ws.getalldata().subscribe(
        data=> {
            this.data = data.slice(-5)
        }
    );

Answer 2

According to the RxJs documentation, if you need to manipulate the 5 most recent items, you can achieve this in RxJs 6 with the following code:

import { concatAll, takeLast } from 'rxjs/operators';

public data: Data[] = [];
...

    this.ws.getalldata().pipe(concatAll(), takeLast(5)).subscribe(
        item=> {
            this.data.push(item);
        }
    );

Another way to accomplish this is by manipulating the array directly,

    this.ws.getalldata().subscribe(
        data=> {
            this.data = data.slice(-5)
        }
    );

How can I display the top 5 data results after subscribing in Nativescript?

Answer №1

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