Apache Solr: Conditionally Display Facet Blocks

Submitted by ebeyrent on Tue, 06/15/2010 - 11:31

In my last post, I showed a method for conditionally displaying facet blocks with Search Lucene, depending on the type of query being performed. This can also be adapted to work for Apache Solr, albeit with a different mechanism. The easiest way to do this with Apache Solr is to use the Context module to control which facet blocks are displayed, along with when and where they are displayed. In this example, I set up a context based on path, where that path was search/apachesolr/*. I then added all of my Apache Solr facet blocks in the context. With the context configured, I now have the ability to alter that context on the fly, based on whatever conditions I choose.

<?php 

/**
 * Implementation of hook_context_active_contexts_alter().
 *
 * <a href="http://twitter.com/param">@param</a> mixed $contexts
 *   Associative array of context objects
 */
function MYMODULE_context_active_contexts_alter(&$contexts) {
  // If one of the active contexts is the apachesolr_search context, remove 
  // some unneccessary blocks
  if(in_array('search-apachesolr-search', array_keys($contexts))) {
    /**
     * Look at the type of query that has been performed, and set a flag regarding whether or 
     * not to show the biblio facets if the type:biblio filter is in effect
     */
    $show_biblio_facets = false;
    $query = apachesolr_current_query();
    if($query) {
      if($query->has_filter('type', 'biblio')) {
        $show_biblio_facets = true;
      }
    }
    // Loop through the apachesolr-search blocks and remove the Biblio facet blocks if needed
    foreach($contexts['search-apachesolr-search']->block as $bid => $block) {
      if(preg_match('/^apachesolr_biblio_/', $bid)) {
        if(!$show_biblio_facets) {
          unset($contexts['search-apachesolr-search']->block[$bid]);
        }
      }
    }
  }
}

?>

In this example, I get all of the active contexts, and if my apachesolr-search context is in effect, I look at the current Apache Solr query to see what filters have been applied. In the example, a flag is set to show the biblio facets if the current search is filtering by the biblio content type. There may be other methods for displaying facets conditionally in Apache Solr; however, I find this method to be fairly straightforward, and if you're not currently using Context for controlling block placement in Drupal, you should definitely reconsider that decision.

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About Erich

Erich is a web developer and a native New Englander who is passionate about life, the universe, and everything.

He is a Drupal consultant, previously employed as a senior developer at Harvard University, working on the IQSS OpenScholar project. Prior to joining the team at Harvard, he was the engineering manager at CommonPlaces e-Solutions, in Hampstead, NH, contributing as the lead engineer on the Greenopolis.com and Twolia.com.

Erich is active in the Drupal community, having contributed modules and patches to the community. He presented at DrupalCon in Szeged Hungary, and co-presented at DrupalCon 2009 in Washington, DC.

Erich lives in New Hampshire with his wife, two sons, and three weimaraners. When not writing code, Erich enjoys landscaping and woodworking.