Exploring the benefits of using TypeScript with Angular2 for HTTP

I have a locally stored "region.json" file containing the following data:

{
  "regionId":1, 
  "region":"CAN"
},
{
  "regionId":2, 
  "region":"CEN"
}

Additionally, I have an "enviroment-app.component.ts" file structured as follows :

import {Component, View, CORE_DIRECTIVES, FORM_DIRECTIVES} from "angular2/core";
import {HTTPTestService} from "./http-test.service";

@Component({
   selector: 'my-app'
})

@View({
  template: `

<table>
    <thead>
        <th>Region Id</th>
        <th>Region</th>
    </thead>
    <tbody>
        <tr *ngFor="#item of myData">
            <td>{{item.regionId}}</td>
            <td>{{item.Region}}</td>
        </tr>
    </tbody>
</table>`
})

export class AppComponent {
    myData:any;
}

Furthermore, there is an "http-test.service.ts" file with the following structure:

import {Injectable} from "angular2/core";
import {Http} from "angular2/http";
import 'rxjs/add/operator/map';
import {Headers} from "angular2/http";
import {AppComponent} from "./environment_app.component";

@Injectable()
export class HTTPTestService {
    constructor (private _http: Http){}

    this.myData = {region:[]};
    
    get("./region.json") {
       return this._http.get("./region.json", { headers: headers })
            .map(res => res.json())
            .subscribe(
                data => {
                    this.myData = data;
                }
            );
    }
}

Despite these configurations, only the header is displayed in the Front-End, as shown https://i.sstatic.net/w2lgB.png.

My goal is to fetch all the JSON data and display it properly.

Any insights on what might be going wrong would be greatly appreciated!

Thank you in advance.

Answer №1

The JSON response is stored in a variable called myData, which belongs to the service and not your AppComponent class.

When using *ngFor="#item of myData", the myData variable referenced belongs to your AppComponent class but has not been populated.

To rectify this:

  1. Create a function similar to the one in your service that retrieves JSON data from a file.
  2. Pass that data back to your AppComponent.
  3. Then assign it to myData within your AppComponent.

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