Recursively outputting panes as JSON

I'm sorry for the late response here.

If you have built the pane, then there is a much easier way to do this. Otherwise, there is no straight-forward way to do this.

For plugins/panes you control, you can check for a 'restful_panels' context in the render callback. For example, this is a 'render callback' for my ctools content type plugin:

/**
 * Callback to render a custom pane.
 */
function example_pane_render($subtype, $conf, $args, $contexts) {
  if (!empty($contexts['restful_panels'])) {
    return example_pane_json_render($subtype, $conf, $args, $contexts);
  }
  else {
    // Just pass it on the admin info which is all we need to show if the node
    // is viewed directly.
    return example_pane_admin_info($subtype, $conf, $contexts);
  }
}

The example_pane_json_render just returns a stdClass object. This structure is sent back as is from the RESTful endpoint. The example_pane_admin_info generates HTML and is not really relevant in a RESTful call. It is only called if the panel is "viewed" normally.

For other types of panels, there are two ways I can think of:

1. Handle this in your RESTful controller itself - parsing/massaging the data depending on your needs.
2. Handle this in the structured panel renderer. This is much more work and I wouldn't recommend it, unless you can't reuse the parsing/massaging logic in your controllers easily.

Do you have any other ideas?