title: Get data once from 2 observables
body: <p>I have 2 observables, and I need to get each observable data only one time.</p>
  
  <p>What I did is subscription inside a subscription, although they can be executed in the same time (in parallel).</p>
  
  <pre><code>let table = this.af.database.object('tables');
      table.subscribe((tableData) =&gt; {
        let section_seats =  this.af.database.object('sections').take(1)
        .subscribe((sectionData) =&gt; {
            //Here I'm Using tableData  &amp; sectionData
  });
  });
  </code></pre>
  
  <p>The code above works great, but they are not executed in the same time although they can.</p>
  
  <p>How I can execute both of the observables in the same time then use the data received from both of them?</p>
  
  <p><strong>Update: Using forkJoin() doing nothing (no console log from the following code)</strong></p>
  
  <pre><code>var source = Observable.forkJoin(
    this.af.database.object('tables'),
    this.af.database.object('sections')
  );
  
  var subscription = source.subscribe(
    function (x) {
      console.log('Next: %s', x);
    },
    function (err) {
      console.log('Error: %s', err);
    },
    function () {
      console.log('Completed');
    });
  </code></pre>