Creating custom filters in views 2

A project that I’m currently working on requires a classifieds system which is fairly straight forward to setup. I’m using the location module for users to specify a location of the classified. To make the search easy I created a simple views page with exposed filters, but I wanted to have a select field with only Australian states.

Out of the box the location module only gives you an exposed autocomplete field for the state/province.

This is what I was trying to achieve.

From this:

To this:

The only way I could do this is with a custom filter.

Creating a custom filter

First we have to let views know about your module.

// in locationstate.module
function locationstate_views_api()
{
  return array(
    'api' => 2,
    'path' => drupal_get_path('module', 'locationstate') . '/inc',
  );
}

To keep the locationstate module directory tidy we’ll place all views file in the /inc folder.

Create a file called locationstate.views.inc in the /inc directory and add the hook_views_data function.

//In locationstate.views.inc
function locationstate_views_data() {

  $data = array();

  if(module_exists('location')) {

    $data['location']['state_au'] = array(
      'title' => t('States AU'),
      'help' => t('Filter by AU states.'),
      'real field' => 'province',
      'group' => t('Location state'),
      'filter' => array(
        'handler' => 'locationstate_handler_filter_state',
      ),
    );
  }

  return $data;
}

Next we’ll have to register the locationstate_handler_filter_state filter so views is aware of it.

You can do this by using the hook_views_handlers function.

//In locationstate.views.inc
function locationstate_views_handlers() {
  return array(
    'info' => array(
      'path' => drupal_get_path('module', 'locationstate') . '/inc',
    ),
    'handlers' => array(
      // The name of my handler
      'locationstate_handler_filter_state' => array(
        // The name of the handler we are extending.
        'parent' => 'views_handler_filter_string',
      ),
    ),
  );
}

Finally we’ll have to create the actual filter file. Because the filter is called locationstate_handler_filter_state, views will search for locationstate_handler_filter_state.inc with in the /inc directory.

Create a file called locationstate_handler_filter_state.inc and paste the following.

class locationstate_handler_filter_state extends views_handler_filter_string {
  /**
   * Shortcut to display the exposed options form.
   */
  function value_form(&$form, &$form_state) {

    $form['value'] = array(
    '#type' => 'select',
    '#title' => t('State'),
    '#options' => array(
      'ACT' => t('ACT'),
      'NSW' => t('NSW'),
      'NT' => t('NT'),
      'QLD' => t('QLD'),
      'SA' => t('SA'),
      'TAS' => t('TAS'),
      'VIC' => t('VIC'),
      'WA' => t('WA'),
      ),
    );

    return $form;
  }
}
}

There you have it, now you should have a custom views filter. Also check out http://thereisamoduleforthat.com/content/fun-views-and-location for more info. I have also attached the module to this post so you guys can download it.

UPDATE: Check this tutorial on creating a filter with SQL joins.
Drupal: How to create Views 2 filters for your new module