title: How to map object value to observable array
body: <p>I am receiving a JSON object from an http get request that has the array of objects I want in its value property.  As I am new to Angular 7 and Rxjs, I can't figure out how to map the array to my objects.</p>
  
  <p>I am getting the data back as any, which brings back the data, to verify it is what I want.  I have gotten arrays of objects back from other API, but they have not been in the value attribute of a parent object.  When I use the tap message to the console, I see what I want to push to my array of objects, but I don't know the mapping syntax.</p>
  
  <p>The JSON below is what I am getting back from the getTfsUsers() method from my user.service.ts.</p>
  
  <p>Below that is the class (assignee.ts) I want to map the data to.</p>
  
  <p>I would like getTfsUsers() to return an observable array of Assignee objects fro</p>
  
  <pre><code>{
      "@odata.context": "https://graph.microsoft.com/v1.0/$metadata#directoryObjects(displayName,mail)",
      "@odata.nextLink": "https://graph.microsoft.com/v1.0/groups/blahblah",
      "value": [
          {
              "@odata.type": "#microsoft.graph.user",
              "displayName": "Deer, John",
              "mail": "deer.john@myplace.org"
          },
          {
              "@odata.type": "#microsoft.graph.user",
              "displayName": "Doe, Jane",
              "mail": "doe.jane@myplace.org"
          },
          {
              "@odata.type": "#microsoft.graph.user",
              "displayName": "Fawn, Mike",
              "mail": "fawn.mike@myplace.org"
          }
       ]
  }
  
  
  </code></pre>
  
  <pre><code>getTfsUsers(): Observable&lt;any&gt;{
      const uri = `${this.groupsBaseUri}/${this.tfsUsersGroupId}/members/${this.displayNameMailFields}`;
      return this.http.get&lt;any&gt;(uri)
        .pipe(
          catchError((error: HttpErrorResponse) =&gt; { return throwError(error); })
        );
    }
  </code></pre>
  
  <pre><code>export class Assignee {
      mail: string;
      displayName: string;
  }
  </code></pre>
  
  <p>Is there a way to map the value attribute from the object being returned to an array of Assignees?</p>