{"id": "changelog:v0-28-faceting", "page": "changelog", "ref": "v0-28-faceting", "title": "Faceting improvements, and faceting plugins", "content": "Datasette  Facets  provide an intuitive way to quickly summarize and interact with data. Previously the only supported faceting technique was column faceting, but 0.28 introduces two powerful new capabilities: facet-by-JSON-array and the ability to define further facet types using plugins. \n                 Facet by array ( #359 ) is only available if your SQLite installation provides the  json1  extension. Datasette will automatically detect columns that contain JSON arrays of values and offer a faceting interface against those columns - useful for modelling things like tags without needing to break them out into a new table. See  Facet by JSON array  for more. \n                 The new  register_facet_classes()  plugin hook ( #445 ) can be used to register additional custom facet classes. Each facet class should provide two methods:  suggest()  which suggests facet selections that might be appropriate for a provided SQL query, and  facet_results()  which executes a facet operation and returns results. Datasette's own faceting implementations have been refactored to use the same API as these plugins.", "breadcrumbs": "[\"Changelog\", \"0.28 (2019-05-19)\"]", "references": "[{\"href\": \"https://github.com/simonw/datasette/issues/359\", \"label\": \"#359\"}, {\"href\": \"https://github.com/simonw/datasette/pull/445\", \"label\": \"#445\"}]"}