How to use voting results to boost relevance for solr search?

Question

I am using search api with the solr backend to index thousands of nodes. All of them have votes (vote api). Now I am wondering how to boost the relevance of these notes by their vote. I don't want to sort the result completely by votes (this would be easy), but that the votes boost the node's relevance for a certain percentage. Is that possible? How to do this?

Answer 1

Do you have the voting api results in your apache solr index? If you do and they are stored under a name ss_votingapi, here is what you need to do:

/*
 * Implements hook_apachesolr_query_alter().
 */
function MYMODULE_apachesolr_query_alter($query) {
  $query->addParam('fl', 'ss_votingapi');
  $query->addParam('bf', "recip(rord(ss_votingapi),1, 1000, 1000)");
}

More here, here and here