Ways to obtain the Map object from HTTPClient in Angular

Question

Ways to obtain the Map object from HTTPClient in Angular

When calling a REST endpoint, the return type is as follows:

ResponseEntity<Map<String, List<Object>>>

How can I handle this response on the Angular side?

I attempted the following approach:

let requiredData = new Map<String, Array<Object>>();
 this.service.getMap().subscribe((mapData) => {
      requiredData = mapData;
}

I am able to successfully log this in the console. However, when I try to retrieve items from the map or fetch keys as shown below, it always returns undefined

requiredData.keys

Does anyone know what the issue might be here?

angular typescript rest

Answer 1

Answer №1

If you're working with TypeScript, the RECORD type can be used to handle Maps effectively. Here is a solution tailored to your specific situation:

requiredData: Record<String,Object[]>;

this.service.getMap()
.subscribe((mapData: Record<String,Object[]>) => {
        this.requiredData= mapData;
      });

In your service file:

getMap(): Observable<Record<String,Object[]>> {
      return this.http.get<Record<String,Object[]>>(
        'your endpoint'
      );
    }

To render the retrieved data on your HTML page, consider the following approach:

<ng-container *ngFor="let dataEntry of requiredData | keyvalue">
   <p>This is the string key : {{ dataEntry.key }}</p>

 <div *ngFor="let item of dataEntry.value">
    <!--Replace id/name with your desired parameters-->
       {{item.id}} -  {{item.name}}
 </div>

Answer 2

If you're working with TypeScript, the RECORD type can be used to handle Maps effectively. Here is a solution tailored to your specific situation:

requiredData: Record<String,Object[]>;

this.service.getMap()
.subscribe((mapData: Record<String,Object[]>) => {
        this.requiredData= mapData;
      });

In your service file:

getMap(): Observable<Record<String,Object[]>> {
      return this.http.get<Record<String,Object[]>>(
        'your endpoint'
      );
    }

To render the retrieved data on your HTML page, consider the following approach:

<ng-container *ngFor="let dataEntry of requiredData | keyvalue">
   <p>This is the string key : {{ dataEntry.key }}</p>

 <div *ngFor="let item of dataEntry.value">
    <!--Replace id/name with your desired parameters-->
       {{item.id}} -  {{item.name}}
 </div>

Answer 3

Answer №2

When you obtain a new HttpClient instance, the default return value is an Object. This HttpClient will automatically execute the response.json() method internally.

To specify the expected type of response from HttpClient, you can do the following:

this.httpClient.get<User[]>(...)
 .map((users) => {
   ...

Answer 4

When you obtain a new HttpClient instance, the default return value is an Object. This HttpClient will automatically execute the response.json() method internally.

To specify the expected type of response from HttpClient, you can do the following:

this.httpClient.get<User[]>(...)
 .map((users) => {
   ...

Ways to obtain the Map object from HTTPClient in Angular

Answer №1

Answer №2

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