To dynamically populate a drop down, please see this documentation:
You will use the gform_pre_render function and will read the WordPress database to return all active users.
In this example http://www.gravityhelp.com/documentation/page/Gform_pre_render#Examples instead of get_posts on line 14, you will use the WordPress function get_users http://codex.wordpress.org/Function_Reference/get_users
To filter the choices in a drop down, you will need to use conditional logic. Conditional logic can be used with radio buttons, checkboxes or drop downs, so you'll need to use a drop down select for your earlier selection.
You may need to do this with two forms, or implement AJAX to get the drop down populated dynamically after the first selection is made (or value is entered for your filter.) Here is one user's explanation of how he accomplished something similar to this: http://www.gravityhelp.com/forums/topic/gform_pre_render-upon-previous-dropdown-condition#post-137821
Can you explain what sort of information your first selection would contain and how that would change the second drop down?
Posted 8 years ago on Monday February 18, 2013 | Permalink