Possible to force facet value on a given page without query string?

Hi JordanMagnuson.

Thanks for the post. My recommendation would actually be to use the search page with a custom filter and then build a dependency plugin to match your condition for three reasons. The first is that it will be tricky to do what you are trying to accomplish with Facet API, and the second is that it will take more processing in that facets are much more expensive than straight filters, and Facet API will also have to re-process the active items. The third reason is that the value is still going to show up in the breadcrumbs, so you are going to have to code your way around that.

With that being said, I am thinking that the easiest way to do what you are asking is to execute the following snippet somewhere before the facets are rendered. Effectively you will alter the facet "parameters" containing the filters to do what you are trying to accomplish.

// The searcher will be named apachesolr@`env-id`.
$adapter = facetapi_adapter_load($searcher);
$url_processor = $adapter->getUrlProcessor();

// Check if the filter is already active.
$filter = "bundle:asset"
$active_items = $adapter->getAllActiveItems();
if (!isset($active_items[$filter])) {

  // If not, get and tamper with your parameters here.
  $filter_key = $url_processor->getFilterKey();
  $params = $url_processor->fetchParams();
  $params[$filter_key][] = $filter;
  $adapter->setParams($params, $filter_key);
}

The code above might be off because I didn't validate it, but play around and see if that works.

Thanks,
Chris

Hm, cool use case. I think this is a great opportunity to show how to build a dependency plugin, so I am going to post some code that you can probably start with and run from there. Just to give some transparency about the dependency plugin system, generally how it works is that the dependencies are satisfied if at least one of the conditions pass. So you can definitely add multiple dependencies to that facet (i.e. content type facet selected or custom filter active) and it will have the either / or effect you are looking for. We already have the content type dependency as you alluded to, so what we are going to do is build a simple dependency plugin to check if a filter is set.

The first thing we are going to do is register our dependency plugin using hook_facetapi_dependencies(), which points to a class containing our dependency plugin.

/**
 * Implements hook_facetapi_dependencies().
 */
function mymodule_facetapi_dependencies() {
  $dependencies = array();

  $dependencies['custom_filter'] = array(
    'handler' => array(
      'label' => t('Custom filter'),
      'class' => 'MymoduleDependencyCustomFilter',
    ),
  );

  return $dependencies;
}

The next thing we are going to do is register the plugin for the facets that we want this dependency to work for by implementing hook_facetapi_facet_info_alter(). This example uses the "bundle" facet, but it could be any facet or combination of facets that you want.

/**
 * Implements hook_facetapi_facet_info_alter().
 */
function mymodule_facetapi_facet_info_alter(array &$facet_info, array $searcher_info) {
  // Only modify node facets related to Apache Solr Search Integration.
  if ('apachesolr' == $searcher_info['adapter'] && isset($searcher_info['types']['node'])) {
    $facet_info['bundle']['dependency plugins'][] = 'custom_filter';
  }
}

Last, we are going to actually write the plugin class. It will be an extension of the abstract class FacetapiDependency, and make sure to put it in Drupal's class registry so it can be autoloaded. See the "files" section. We will override the settingsForm() and getDefaultSettings() methods to define the UI, and we will implement the execute() method to execute the plugin.

/**
 * Dependency plugin that checks whether a custom filter is set.
 */
class MymoduleDependencyCustomFilter extends FacetapiDependency {

  /**
   * Implements FacetapiDependency::execute().
   */
  public function execute() {
    if ($this->settings['custom_filter']) {

      // Get the Apache Solr Search Integration search page we are currently on.
      $pages = &drupal_static('apachesolr_search_page_load', array());
      $page_id = key($pages);

      // Dependency fails if we don't have a search page or custom filter.
      if ($page_id && !empty($pages[$page_id]->settings['fq'])) {

        // Iterate over filters to check if we have a match.
        $filters = $pages[$page_id]->settings['fq'];
        foreach ($filters as $filter) {
          // NOTE: This is only good for really simple use cases!!
          if (FALSE !== strpos($filter, $this->settings['custom_filter'])) {
            return; // This dependency passed, so defer to other dependencies.
          }
        }
      }

      // This dependency failed because there was no match or custom filter.
      return FALSE;
    }
  }

  /**
   * Overrides FacetapiDependency::settingsForm().
   */
  public function settingsForm(&$form, &$form_state) {
    $form[$this->id]['custom_filter'] = array(
      '#title' => t('Custom filter'),
      '#type' => 'textfield',
      '#default_value' => $this->settings['custom_filter'],
      '#description' => t('Checks for the presence of this custom filter.'),
    );
  }

  /**
   * Overrides FacetapiDependency::getDefaultSettings().
   */
  public function getDefaultSettings() {
    return array(
      'custom_filter' => '',
    );
  }
}

If all went well, you will be able to configure your dependency. Simply add the filter you are checking for in the text field, and it will be required for the dependency to pass.

The match in the execute() method will have to be more sophisticated to work for complex use cases, but you get the idea :-).

Good luck,
Chris

JordanMagnuson, thanks for posting your updates! I think that as long as the code works as expected, then run with it.

The reason why my code checked for the first search page (which I agree is hacky) is because there are some instances where there will be a "%" in the path and it therefore won't match the current_path(). If your pages don't have a %, then your code will work fine. I am wondering if there is some middle ground to solve this use case more reliably, but that is a whole other topic :-)

Anyways, great work, and thanks for posting back.
Chris

To follow up, you are right, my code is borked. It breaks under certain conditions. As a workaround, I came up with another snippet that I am using in another module. See the apachesolr_stats_get_page_id() function.