28 Faceted search

var result = db.Query<IEvent>()
               .Where(e => e.Status == EventStatus.Published)
               .WhereSearch("jazz")
               .Facets()
               .AddValueFacet(e => e.Status)                 // a bucket per value
               .AddRangeFacet(e => e.Price)                  // ranges chosen by the engine
               .AddRangeFacet(e => e.Price, 0m, 250m)        // …plus a range of your own
               .AddFacet(e => e.Tags)                        // the engine picks values or ranges
               .SetFacetOptions(e => e.Tags, maxValues: 20, minCount: 1, sortByCount: true)
               .Page(0, 20)
               .Execute();

foreach (var facet in result.Facets) {
    Console.WriteLine(facet.DisplayName);
    foreach (var v in facet.Values)
        Console.WriteLine($"  {v} ({v.Count}){(v.Selected ? " ←" : "")}");
}

• Applying the user's selection — The same builder applies what the user clicks. A selected value filters the result and comes back with Selected set:
• Facet declaration methods — Each method takes the property as an expression, a name or an id. Faceting needs Indexed = true. NotFacet = true keeps a property out, and a relation takes part only with [RelationProperty(Facet = true)].
• Where the un-named facets come from — With no facet named, a facet query counts every facetable property of every node type in the result. Naming a facet turns this off. These methods choose explicitly, and combine with the facets you name:
• 28.1 Pivot tables — A pivot summarises the matching nodes as a table, like a spreadsheet pivot table. Rows and columns are groups of nodes by property value, and each cell holds measures over its nodes. A pivot returns the table, not the…
• 28.2 GroupBy — GroupBy is SQL's GROUP BY, written the way LINQ and EF Core write it. It is the typed, one-axis form of a pivot and runs on the same engine. Use it in application code, and a pivot for two axes, sub-totals, or tables…