title: Angular 4.0 http put request
body: <p>I've written a function to send a http put request to update some data but it says, that it is not recieving any data:</p>
  
  <pre><code>updateHuman(human: Human) {
      const url = `${this.url}/${human.id}`;
      const data = JSON.stringify(human);
      return this.http.put(url, data).map(
          response =&gt; response.json().data as Human,
          error =&gt; console.log(error)
      );
  }
  </code></pre>
  
  <p>After I've changed my function to the following, it is working:</p>
  
  <pre><code>updateHuman(human: Human) {
      const url = `${this.url}/${human.id}`;
      const data = JSON.stringify(human);
      return this.http.put(url, data).map(() =&gt; human);
  }
  </code></pre>
  
  <p>Could someone explain me, why the first function is not working but second is working?</p>