Custom Field with autcomplete - drupal-7

Question

I am trying to build my own node reference custom field - I know several projects out there already do this, I am building this in order to learn... :)
My problem is the autocomplete path, it's not being triggered, I have checked the noderefcreate project and implemented my solution based on that project. But still; nothing is being triggered when I check firebug.
Here is my code:
function nodereference_field_widget_info() {
return array(
'nodereference_nodereference_form' => array(
'label' => t('Node Reference Form'),
'field types' => array('nodereference'),
'behaviors' => array(
'multiple values' => FIELD_BEHAVIOR_DEFAULT,
'default value' => FIELD_BEHAVIOR_DEFAULT,
),
'settings' => array(
'autocomplete_match' => 'contains',
'autocomplete_path' => 'nodereference/autocomplete',
),
),
);
}
function nodereference_field_widget_form(&$form, &$form_state, $field, $instance, $langcode, $items, $delta, $element) {
if ($instance['widget']['type'] == 'nodereference_nodereference_form') {
$widget = $instance['widget'];
$settings = $widget['settings'];
$element += array(
'#type' => 'textfield',
'#default_value' => isset($items[$delta]['nid']) ? $items[$delta]['nid'] : NULL,
'#autocomplete_path' => $instance['widget']['settings']['autocomplete_path'],
);
}
return array('nid' => $element);
}

Answer 1

You need to define method from where auto compete will take suggestions.
It can be done like this:
/**
* implements hook_menu
*/
function your_module_name_menu() {
$items['master_place/autocomplete'] = array(
'page callback' => '_your_module_name_autocomplete',
'access arguments' => array('access example autocomplete'),
'type' => MENU_CALLBACK
);
return $items;
}
/**
* Auto complete method implementation
* #param $string
*/
function _your_module_name_autocomplete($string) {
$matches = array();
// Some fantasy DB table which holds cities
$query = db_select('target_db_table', 'c');
// Select rows that match the string
$return = $query
->fields('c', array('target_column'))
->condition('c.target_column', '%' . db_like($string) . '%', 'LIKE')
->range(0, 10)
->execute();
// add matches to $matches
foreach ($return as $row) {
$matches[$row->city] = check_plain($row->city);
}
// return for JS
drupal_json_output($matches);
}