title: How do I retrieve all applicable facet fields for a Solr search
body: <p>I'm trying to use Solr for faceted-seaarch on a website.</p>
  
  <p>When a user fires off a search query, I query Solr and retrieve the search results which can then be displayed.</p>
  
  <p><strong>My question is - how do I find out which facet fields and terms are applicable to the search results?</strong></p>
  
  <p>To be clear - different categories of products have different facet fields and I want to find a way to bring back the most relevant facet fields for the search results that have been returned.  I don't want to have to specify the fields - I'd like Solr to identify the relevant ones for me.</p>
  
  <p>Thanks in advance! </p>