Drupal + Solr, boost result based on custom node weight
To provide the score as a sort option add it in the prepare_query hook:

function mymodule_apachesolr_prepare_query(&amp;$query, &amp;$params, $caller) {
  $query-&gt;set_available_sort('field_score', array('title' =&gt; t('Score'), 'default' =&gt; 'desc'));
}


To boost by it you'll need to either:


Go to Site settings -> Apachesolr -> Search fields and if the score field appears there give it a value bigger than all the other fields to make it the most relevant.
If the field doesn't appear (due to the type it might not appear) or you want more control (like calculate the boost value on every query) you can add the boost in the modify_query hook with something like this: $params['qf'][] = 'field_score^10';.