Angular 4, convert http response observable to object observable : <p>I'm new to the concepts of observables and need some help with a conversion.<br>
I have a service which returns an <code>Observable&lt;Response&gt;</code> from a Http request, but I need to convert it do an <code>Observable&lt;PriceTag&gt;</code> to use it on a <code>DataSource</code> inside the connect method.<br>
Is there anyway to do this?</p>

<p>This is the method from my service:</p>

<pre><code>getPriceTags(): Observable&lt;Response&gt; {

    // Set the request headers
    const headers = new Headers({ 'Content-Type': 'application/json' });

    // Returns the request observable
    return this.http.post(Constants.WEBSERVICE_ADDRESS + "/priceTag", null, {headers: headers});

}
</code></pre>

<p>And here is the DataSource class where I need to return it as an <code>Observable&lt;PriceTag&gt;</code>:</p>

<pre><code>export class PriceTagDataSource extends DataSource&lt;PriceTag&gt; {

    constructor (private priceTagService: PriceTagService) {
        super();
    }

    connect(): Observable&lt;PriceTag&gt; {

        // Here I retrieve the Observable&lt;Response&gt; from my service
        const respObs = this.priceTagService.getPriceTags();

        // Now I need to return a Observable&lt;PriceTag&gt; 

    }

    disconnect() {}

}
</code></pre>

<p>Here's an example from the response from my request:</p>

<pre><code>{
    // This object is used to check if the query on the server was sucessful
    "query": {
        "sucessful": true
    },

    // These are my PriceTags 
    "tags": [
        {
            "id": "1",
            "name": "MAIN"
        },
        {
            "id": "2",
            "name": "CARD"
        }
    ]
}
</code></pre>
