OK I know this question has been asked multiple times from people in different ways but I haven’t been able to pinpoint my exact use case or solution.

I have a registration form that I want to prefill the default values after the user selects an option from a select list. After they select an option, AJAX fires off to see if the user is in our CRM, and runs a series of code to look up information. I then want that found information to show in the various form fields on the page.

Couple key things to point out that I often find in other solutions that do not work for me:

• The user is NOT submitting. They are still doing work on the form, the first form field sets up their experience going forward.
• Setting the field info in $ form_state[‘values’] doesn’t work. Nothing is set.
• Settings the field info $ form_state[‘input’] does work, but then if a user changes any of the values in the fields, that new change isn’t set.

Here is a stripped down example of what is being done.

function ces_user_registration_form_commerce_checkout_form_registration_alter(&$  form, &$  form_state, $  form_id) {     foreach ($  form['registration_information']['register_entities'] as $  name => $  data) {         foreach($  form['registration_information'][$  name] as $  subname => $  subdata) {             $  form['registration_information'][$  name][$  subname]['register_for']['#ajax'] = array(                 'wrapper' => 'commerce-checkout-form-registration',                 'callback' => 'ces_user_registration_form_register_for_ajax_callback',                 'method' => 'replace'             );         }     } } 

and the callback

function ces_user_registration_form_register_for_ajax_callback($  form, &$  form_state) {     foreach ($  form['registration_information']['register_entities'] as $  name => $  data) {         foreach($  form['registration_information'][$  name] as $  subname => $  subdata) {             if(!empty($  form_state['values']['registration_information'][$  name][$  subname]['register_for']) && $  form_state['values']['registration_information'][$  name][$  subname]['register_for'] == 'registration_registrant_type_me' ){                 // run our code for comparing user values with CRM                 // return object with CRM data                 // below are example static value settings that I have tried                  // doesn't work                 $  form['registration_information'][$  name][$  subname]['field_first_name']['und'][0]['value']['#default_value'] = "travis";                  // doesn't work                 $  form_state['values']['registration_information'][$  name][$  subname]['field_first_name']['und'][0]['value'] = "travis";                  // Worked but doesn't save field changes after filled                 $  form_state['input']['registration_information'][$  name][$  subname]['field_first_name']['und'][0]['value'] = "travis";             }         }     }     return $  form }