title: Merge new GET param with current route in Twig
body: <p>I have a question. I'm creating a view file for product listing which have filter function. For example, My current Url is </p>
  
  <pre><code>mysite/category/electronics?p=1
  </code></pre>
  
  <p>And in my template I have <strong>a</strong> tag to add a some filter criteria. When click on a, I want my uri will be <code>mysite/category/electronics?p=1&amp;c=2</code> for example.</p>
  
  <p>But I don't know what's the best practice to generate href for <strong>a</strong> tag, by current uri(app.request.uri) or generate uri from route (use path())..... Waiting for help!</p>