How to use HTTP POST method with in-memory web api and get updated object in response?

Question

This is the object I am updating:

    {
      learning_node_id: 1001,
      status: 'EN',
      overall_progress: 78,
      difference: 2
    },

I am sending a POST request using a data service on a click event which is as follows:

getProgressDatabyId(nodeId: number, resourceStatus: string): Observable<IResourceProgress> {
    const url = `${this.progressUrl}/?learning_node_id=${nodeId}`;
    var json = JSON.stringify({progress_data : { status: resourceStatus }});
    return this.http.post(url, json, { headers: this.headers })
      .map(this.extractData)
      .catch(this.handleError);
  }

I am expecting response as following:

    {
      learning_node_id: 1001,
      status: 'CO',
      overall_progress: 78,
      difference: 2
    },

The response which I am getting is: { id: 1, progress_data: { status: "CO"; } }

I am not able to understand why I am not able to get the exact updated object?