Panels 3: Pane Visibility Rules (Evaluating $contexts Variable)

Panel panes can be configured to appear when PHP code evaluates TRUE.

For example, a pane displaying the field(s) for a node may only make sense when that field actually has values.

Using the $contexts variable available to content pane visibility settings, one can evaluate such a condition in PHP.

1. Add a new rule
   
   
   
   
2. Inspect the $contexts variable
   

   While the PHP code must ultimately return a boolean value, temporarily output the contents of our $contexts variable using drupal_set_message():

   
   
   drupal_set_message('Contexts:<br /><pre>'.print_r($contexts,1).'</pre>');
   
   

   Visit your Panels page and you will see the output of the entire $contexts variable -- a variety of nested objects and arrays pertaining to the page.

   
   

3. Evaluate your condition(s)
   

   After finding the $contexts properties or element(s), return a boolean value (optionally using the negation (NOT) option instead of a PHP operator):

   
   
   return empty($contexts['argument_entity_id:node_1']->data->field_file);
   
   
   

In this example, the panel pane will only appear when the specified condition is met--when the array defining the node's file_field property (array) is not empty.