title: how to force to refresh value of model in yii
body: <p>let's say I have model A with relation to B.</p>
  
  <p>When I write:</p>
  
  <pre><code>$a = A::model()-&gt;findByPK(1);
  $a-&gt;B-&gt;doSomething();
  </code></pre>
  
  <p>and now B may by changed (by other user for instance). When I write:</p>
  
  <pre><code>$a-&gt;B-&gt;doSomething(); 
  </code></pre>
  
  <p>it uses old values of B. What I should do to force to refresh value of B before doSomething().</p>