How to change a filter handler of the view?

Question

I have created a nice Filter Handler for my View, and I set it up using hook_views_data_alter.

Does this mean that this will ALWAYS be the Filter Handler for this particular field? What if I want a different Filter Handler later, in a different view?

How can I specifically say "Only use the X handler on page X?"

For posterity, I thought I'd outline more of what I was trying to accomplish here:

I have "Friends" page and a "Content" page. On the "Content" page, I wanted to be able to filter by "Content posted by my friends." However, on the "Friends" page I want to filter by "Users in my Groups." Both of these query on the user.uid field, so it was making the filters the same, even though I wanted totally different logic for the two views.

Answer 1

Nope currently there is no explicit way to achieve it. However there is an workaround.

1. Using hook_views_data_alter make your custom handler as the filter instead of existing one(You already did that)
2. In your custom filter handler, add a new option to select which filter operation it needs to perform(whether normal one or custom one), Eventually a yes/no field.

Below is the example on adding extra options to the filter handler,

    function option_definition() {
      $options = parent::option_definition();

      $options['custom_filtering'] = array('default' => 0);

      return $options;
    }

    function extra_options_form(&$form, &$form_state) {
      parent::extra_options_form($form, $form_state);

      $form['custom_filtering'] = array(
        '#type' => 'checkbox',
        '#title' => t('Custom Filtering'),
        '#default_value' => $this->options['custom_filtering'],
        '#description' => t('Check this if you want to perform the custom filtering on this field instead of a regular filtering mechanism'),
      );
    }

3.Based on the above option do your filter mechanism like below,

function query() {
    // Do Custom filtering based on the option selected.
    if ($this->options['custom_filtering']) {
      // Do your custom filtering.
    }
    else {
      // Do regular filtering.
    }
  }

Now when you're adding the filter for this field, you can just select which filtering it needs to perform.

Edit by OP (I don't even know how I have the rights to do this): You must additionally implement the following:

function has_extra_options() { return TRUE; }

And then your extra options will be displayed!

Answer 2

I always take the following approach: Copy the existing views_data code via php:

// Copy the existing definition.
$data['table']['field_special'] = $data['table']['field'];
// Force the real field, so views still consider it as a different field in SQL.
$data['table']['field_special']['real field'] = 'field';
// Set a special handler.
$data['table']['field_special']['field']['handler'] = 'foo_handler_field_...';

This allows you to easy reuse the custom handler if needed, but at the same time not conflict with existing views.

In contrast to the approach of berliner (which certainly works) this does not add any runtime code execution, which adds potential bugs. This approach just uses basically configuration.