title: MODx MIGX variable in json string
body: <p>I have a little problem with using a variable inside the where-json-string.
  I'm running a MIGX getImageList inside an other MIGX getImageList -template.</p>
  
  <pre><code>[[getImageList? 
  &amp;tvname=`migxProducts` 
  &amp;where=`{"productGroupName:=":"[[+productGroupName]]","productItemType:=":"product"}` 
  &amp;tpl=`migxProductsListRowTpl`]]
  </code></pre>
  
  <p>It seems that it's the [[+productGroupName]] that breaks it all. I need to use that variable in the where string.</p>
  
  <p>Any clue of what's wrong or if there's a solution?</p>
  
  <p>Thanks in advance.</p>