Add custome auto-complete path views expose filter

By default, the Drupal 7 core provides the necessary functionality to implement the autocomplete widget for users and taxonomy (Hint: search the Drupal 7 core for '#autocomplete_path'). With that in mind, outside of a quick hook_form_alter all I needed to do was appropriate the existing code and then tweak it to my needs.

You can add own autocomplete path to any form fields:

 

Use hook_form_alter to set an autocomplete path for the field

 /**
     * Implements hook_form_alter 

    * Alter form ids are views_exposed_form adding custome ajax path in search    location filter; 

*/

function hook_form_alter(&$form, &$form_state, $form_id){

if($form['#form_id']=='views_exposed_form' && $form['#id']=='views-exposed-form-search-store-page')

     {

      // field name for auto complete

        $form['field_location_locality']['#autocomplete_path']='demo-autocomplete-engine';
     }
}

Define a menu callback for the autocomplete path in hook_menu

/**
* Implementation of hook_menu.
*/
function hook_menu() {
  $items = array();

  $items['demo-autocomplete-engine'] = array(
    'page callback' => 'hook_autocomplete',
    'access callback' => TRUE,
  );
 
  
  return $items;
}

Have the callback query the database

/**

* Implements custome autocomplete function 

* Retrieve a JSON object containing autocomplete suggestions for field value.

*/  

function hook_autocomplete($text) {

 global $base_url,$base_path,$theme_path,$user;

  $results = array();

   $query = db_select('field_data_field_location', 'c');

   $query

      ->condition('c.field_location_locality', '%' . db_like($text) . '%', 'LIKE')

      ->fields('c', array('field_location_locality'))

      ->groupBy('field_location_locality')

      ->orderBy('field_location_locality', 'ASC')

      ->range(0,10);

  $sql_results = $query->execute();

 if(!empty($sql_results) AND $sql_results->rowCount() > 0){

  foreach ($sql_results as $row) {

   $results[$row->field_location_locality] = check_plain($row->field_location_locality);

  }

 }else{

  $results[0] = check_plain('No results. Please try something else');

 }

 

  drupal_json_output($results);

}

After this step assure that your cache are clear.

The final function in our module queries our database and returns 10 results. The autocomplete widget uses JavaScript, so after the $results array has been populated we then convert the output to json!