====== Facets ======

One of VuFind's most prominent features is faceted search, which allows a result set to be narrowed down based on values displayed in a sidebar.

Notes:

  * VuFind allows for "configuration" of facets in terms of which facets to show and in which order.  Just edit [[configuration:files:facets.ini]] in your favorite text editor to adjust Solr faceting. If you are not using Solr, most [[configuration:third-party_content|third-party content providers]] also allow faceting, which can be configured in the appropriate .ini file (e.g. [[configuration:files:summon.ini|Summon.ini]], etc.).

  * One helpful way to understand facets is to submit queries to Solr to return faceted results directly in XML: See http://wiki.apache.org/solr/SimpleFacetParameters and scroll all the way down for examples of URLs. You can also turn on debug mode in [[configuration:files:config.ini]] to see exactly which URLs VuFind is generating for its own queries.

  * More details on adding facets (with a particular focus on building them using data in MARC records) can be found on [[indexing:adding_facets|this page]].

===== Hierarchical Facets =====

VuFind supports hierarchical facets with Solr. The facet values need to be indexed as described in the [[https://wiki.apache.org/solr/HierarchicalFaceting#Terms_Containing_Another_Term_in_the_Beginning|Solr wiki]] with each value always ending in a trailing slash. Hierarchical facets are defined in facets.ini (see the SpecialFacets section) and there are also settings that define how they are sorted and displayed. 

Below is an example of how a building facet could be indexed when the record belongs to a couple of different libraries:

  0/MainLib/
  1/MainLib/Adults/
  1/MainLib/Reference/
  0/BranchLib/
  1/BranchLib/Main/

Below is an example of format could be indexed for a record that contains physical copies as well as an online version:

  0/Book/
  1/Book/Book/
  1/Book/eBook/

===== Related Video =====

Some of the topics from this page are also covered in the [[videos:configuring_search_and_facet_settings|Configuring Search and Facet Settings]] video.