title: how to call service from controller in grails
body: <p>I have a service class and i am trying to call the method of the service  in my controller as below.</p>
  
  <pre><code>class LogListController {
  
  def ListLogDetails = { 
      println "We are inside List log Details--&gt;"+params
      def logListHelperService
      logListHelperService.getFilePath(params)
  }}
  </code></pre>
  
  <p><strong>Exception Message: Cannot invoke method getFilePath() on null object</strong> </p>
  
  <p>what is my mistake there..</p>