title: how to check null /empty or value based on response from previous Sampler in Jmeter?
body: <p>I have extracted the value from Json response for one of the Key. It has two possible values as either </p>
  
  <pre><code>Key=[] or 
  Key=[{"combination":[{"code":"size","value":"Small"}]},{"combination":
  [{"code":"size","value":"Medium"}]}]
  </code></pre>
  
  <p>I need to check whether Key is [] or it has some values. Could you please help me what is wrong with below implementation:</p>
  
  <pre><code>if ("${Key}"=="[]") {
  vars.put('size', 'empty')
  } else {
  vars.put('size', 'notempty')
  }
  </code></pre>
  
  <p>My Switch controller is not navigating to Else Part based on above implementation . Help is useful!</p>