To display hierarchy in taxonomy facets, you need to do two main things:
- Make sure your taxonomy field is being indexed with taxonomy hierarchy data intact.
- Set up the Facet API facet for this taxonomy term so it will display the full hierarchy.
If you follow all steps in Jeff Geerling Post and there were no “Flatten hierarchy” and “Treat parent items as individual facet items” fields:
- Make sure in FIELDS tab you select taxonomy reference field, not related-fields.
- How can I show parent and child terms in facet search filter block for a taxonomy field having simple hierarchial select as widget type
Long tailed titles:
- FIELD tab in Index Server configuration
- Taxonomy term in Search API and Facet API