title: Valid ng-src syntax for string concatenation inside directive template string
body: <p>I have an ng-src attribute within an image tag that is loaded as a string from the template property of a directive, which supposed to load an image selected by the user. However when the page loads, the console outputs a 404 since there is no image selected and ng-src is loading an empty image. What I currently have is this</p>
  
  <pre><code>"&lt;img  ng-src="myserver.com/{{imagesPath+ selectedImage}}"&gt;&lt;/img&gt;"
  </code></pre>
  
  <p>but whenever <code>selectedImage</code> is an empty string I get the empty request.</p>
  
  <p>What I tried changing it to was </p>
  
  <pre><code>"&lt;img class='snapshot' ng-src='{{selectedImage.length? \'myserver.com\' + imagesPath +selectedImage : \'\' }}'&gt;&lt;/img&gt;"
  </code></pre>
  
  <p>And this does not work. What is the correct syntax?</p>