title: Yii2 - prevent behavior on insert
body: <p>I have this behavior in my model:</p>
  
  <pre><code>public function behaviors()
      {
          return [
              'styles' =&gt; [
                  'class' =&gt; ImageStyleBehavior::className(),
                  'path' =&gt; \Yii::getAlias('@webroot') . '/files/userphotos/styles',
                  'url' =&gt; \Yii::getAlias('@web') . '/files/userphotos/styles',
                  'attribute' =&gt; 'photo',
                  'styles' =&gt; [
                      '300x300' =&gt; [$this, 'style300'], //can be any valid callable
                      '100x100' =&gt; [$this, 'style100'], //can be any valid callable
                  ]
              ]
          ];
      }
  </code></pre>
  
  <p>The photo have default value of <strong>noavatar.png</strong>, and when I try to insert, I get this error:</p>
  
  <pre><code>Exception 'Imagine\Exception\RuntimeException' with message 'Unable to open image /var/www/c2c/Care2Shine/www/files/userphotos/' 
  </code></pre>
  
  <p>Is there a way for me to prevent behavior on insert actions? </p>