> I've noticed that performing a query with facet.mincount=0 > and no fq clauses > results in a response where only facets with non-zero > counts are returned, > but adding in an fq clause (caused by a user selecting a > non-zero-valued > facet value checkbox) actually causes a bunch of 0-count > facet values > completely unrelated to the query to be returned. > > Is adding the fq constraint actually widening the query > before > facet.mincount gets applied? > > E.g., say a query with no fq constraint produces the > following facet values: > > ID > 1234 (1) > 1111 (15) > 1010 (30) > > Title > Red (11) > Green (15) > Blue (32) > > but when the user selects Blue (32), and I add > &fq=Color:Blue, Solr returns > the following: > > ID > 1 (0) > 2 (0) > 3 (0) > ... > 99 (0) > 100 (0) > > Color > Orange (0) > Teal (0) > Red (0) > Green (0) > Blue (32) > > > Notice how, before the fq clause is added, none of the > 0-count facets are > returned, even though facet.mincount = 0, but afterward, a > bunch of 0-count > facets are returned?
This is normal. > The context of my question is trying to solve a problem > where the > application must display facet values with a count of zero > as filtering > operations remove them from the result set. That is, > if Red (10) was > displayed after the initial query, but the user filters on > Blue (32), then > we must still display Red (0) so the user can select it and > widen the query. > Initially, we were using mincount=1 and managing the > missing facets entirely > within the application, but now I'm trying to see if we can > use mincount=0 > and maybe some other constraints to achieve the same > behavior without a lot > of custom code in the application. I couldn't fully follow, but you want something like multi-select faceting? http://search-lucene.com/ is an example for that, user can select solr and lucene from the project facet at the same time. http://wiki.apache.org/solr/SimpleFacetParameters#Multi-Select_Faceting_and_LocalParams
