Whereas earlier versions required custom code, a recent addition to Solr enables faceted browsing out of the box.
For example, adding the following parameters to your query. assuming you have “category” and “inStock” fields in your data:
facet=true facet.field=category facet.field=inStock
Adds something like this to the search results:
<lst name="facet_counts"> <lst name="facet_queries"/> <lst name="facet_fields"> <lst name="category"> <int name="music">1</int> <int name="connector">2</int> <int name="drive">21</int> </lst> <lst name="inStock"> <int name="false">3</int> <int name="true">1</int> </lst> </lst> </lst>
Showing which facets exist for the category and inStock fields, including result counts for each.
More details are available on the solr-user mailing list.
This is way cool, and comes right on time for my current project!
bertrand's brain grep 