title: AngularJS - $scope variable is not binding
body: <p>I'm working on a form in which the user enters his zip code (Brazilian zip code), and clicks on a button that automatically refreshs the inputs with all his address info.
  I've done a button so the user could see his address in Google Maps, but the two way data-binding seems not to work.</p>
  
  <p>This is the variable that configs the url of google maps:</p>
  
  <pre><code>this.$scope.url = this.$scope.entity.address.logradouro + ' ' +
                      this.$scope.entity.address.numero + ' ' + this.$scope.entity.address.localidade + ' ' + this.$scope.entity.address.uf;
  </code></pre>
  
  <p>And here is the data-binding in the page: </p>
  
  <pre><code>&lt;a href="https://www.google.com.br/maps/place/{{url}}" target="_blank" class="btn btn-primary btn-primary"&gt;GOOGLE MAPS &lt;span class="glyphicon glyphicon-globe"&gt;&lt;/span&gt;&lt;/a&gt;
  </code></pre>
  
  <p>When I click, the address on google maps url is: </p>
  
  <blockquote>
    <p><a href="https://www.google.com.br/maps/place/null%20null%20null%20null" rel="nofollow">https://www.google.com.br/maps/place/null%20null%20null%20null</a></p>
  </blockquote>
  
  <p>How do I solve this? Thanks!</p>
  
  <p>P.S. All the other data-bindings are working.</p>