V4.0 Facet Drill Down and Drill Sideways support

docs/articles/searching.md

@@ -437,6 +437,117 @@ var createdFacetResults = results.GetFacet("Created"); // Returns the facets for
 var firstRangeValue = createdFacetResults.Facet("first"); // Gets the IFacetValue for the facet "first"
 ```
 
+### DrillDown Query
+
+DrillDown query is used to drill down and sideways on facets.
+
+#### Basic MatchAll Query example
+
+```csharp
+// Setup
+
+// Create a config
+var facetsConfig = new FacetsConfig();
+facetConfigs.SetHierarchical("publishDate", true);
+
+services.AddExamineLuceneIndex("MyIndex",
+    // Set the indexing of your fields to use the facet type
+    fieldDefinitions: new FieldDefinitionCollection(
+        new FieldDefinition("publishDate", FieldDefinitionTypes.FacetTaxonomyFullText),
+        new FieldDefinition("Author", FieldDefinitionTypes.FacetTaxonomyFullText)
+        ),
+    // Pass your config
+    facetsConfig: facetsConfig,
+    // Enable the Taxonomy sidecar index, required for Heirachy facets
+    useTaxonomyIndex: true
+    );
+
+
+var searcher = myIndex.Searcher;
+var results = searcher.CreateQuery()
+    .DrillDownQuery(
+        dims =>
+        {
+            // Specify the dimensions to drill down on
+            dims.AddDimension("Author", "Lisa");
+        },
+        null // Optional base query to drill down over
+        ,
+        sideways =>
+        {
+            // Drill Sideways for the top 10 facets
+            sideways.SetTopN(10);
+        },
+        BooleanOperation.Or // Default operation for boolean subqueries
+        )
+        .WithFacets((Action<IFacetOperations>)(facets =>
+        {
+            //Fetch the facets
+            facets.FacetString("publishDate", x => x.MaxCount(10));
+            facets.FacetString("Author", x => x.MaxCount(10));
+        }));
+    .Execute();
+
+var publishDateResults = results.GetFacet("publishDate"); // Returns the facets for the specific field publishDate
+var AuthorFacetResults = results.GetFacet("Author"); // Returns the facets for the specific field publishDate
+
+```
+
+#### Basic BaseQuery example
+
+```csharp
+// Setup
+
+// Create a config
+var facetsConfig = new FacetsConfig();
+facetConfigs.SetHierarchical("publishDate", true);
+
+services.AddExamineLuceneIndex("MyIndex",
+    // Set the indexing of your fields to use the facet type
+    fieldDefinitions: new FieldDefinitionCollection(
+        new FieldDefinition("publishDate", FieldDefinitionTypes.FacetTaxonomyFullText),
+        new FieldDefinition("Author", FieldDefinitionTypes.FacetTaxonomyFullText)
+        ),
+    // Pass your config
+    facetsConfig: facetsConfig,
+    // Enable the Taxonomy sidecar index, required for Heirachy facets
+    useTaxonomyIndex: true
+    );
+
+
+var searcher = myIndex.Searcher;
+var results = searcher.CreateQuery()
+    .DrillDownQuery(
+        dims =>
+        {
+            // Specify the dimensions to drill down on
+            dims.AddDimension("Author", "Lisa");
+        },
+         baseQuery => // Optional base query to drill down over
+        {
+            return baseQuery.Field(ExamineFieldNames.CategoryFieldName, "content");
+        } 
+        ,
+        sideways =>
+        {
+            // Drill Sideways for the top 10 facets
+            sideways.SetTopN(10);
+        },
+        BooleanOperation.Or // Default operation for boolean subqueries
+        )
+        .WithFacets((Action<IFacetOperations>)(facets =>
+        {
+            //Fetch the facets
+            facets.FacetString("publishDate", x => x.MaxCount(10));
+            facets.FacetString("Author", x => x.MaxCount(10));
+        }));
+    .Execute();
+
+var publishDateResults = results.GetFacet("publishDate"); // Returns the facets for the specific field publishDate
+var AuthorFacetResults = results.GetFacet("Author"); // Returns the facets for the specific field publishDate
+
+```
+
 ## Lucene queries
 
 Find a reference to how to write Lucene queries in the [Lucene 4.8.0 docs](https://lucene.apache.org/core/4_8_0/queryparser/org/apache/lucene/queryparser/classic/package-summary.html#package_description).

src/Examine.Core/Search/IDrillDownQueryDimensions.cs

@@ -0,0 +1,18 @@
+namespace Examine.Search
+{
+    /// <summary>
+    /// Drill-down Query Dimensions
+    /// </summary>
+    public interface IDrillDownQueryDimensions
+    {
+        /// <summary>
+        /// Adds one dimension of drill-downs.
+        /// Repeated dimensions are OR'd with the previous contraints for the dimension.
+        /// All demensions are AND'd againt each other and the base query.
+        /// </summary>
+        /// <param name="dimensionName">Dimension Name</param>
+        /// <param name="paths">Facet Category Paths</param>
+        /// <returns></returns>
+        IDrillDownQueryDimensions AddDimension(string dimensionName, params string[] paths);
+    }
+}

src/Examine.Core/Search/IDrillSideways.cs

@@ -0,0 +1,15 @@
+namespace Examine.Search
+{
+    /// <summary>
+    /// Drill Sideways Options
+    /// </summary>
+    public interface IDrillSideways
+    {
+        /// <summary>
+        /// Set the number of Top Documents
+        /// </summary>
+        /// <param name="topN">Number of Top Documents</param>
+        /// <returns></returns>
+        IDrillSideways SetTopN(int topN);
+    }
+}

src/Examine.Core/Search/IFacetOperations.cs

@@ -31,5 +31,12 @@
         /// Add a range facet to the current query
         /// </summary>
         IFacetOperations FacetLongRange(string field, params Int64Range[] longRanges);
+
+        /// <summary>
+        /// Return all Facet Dimensions that had hits
+        /// </summary>
+        /// <param name="maxCount">Maximum number of terms to return</param>
+        /// <returns></returns>
+        IFacetOperations FacetAllDimensions(int maxCount);
     }
 }

src/Examine.Core/Search/IOrdering.cs

@@ -40,6 +40,13 @@
         /// Return all fields in the index
         /// </summary>
         /// <returns></returns>
-        IOrdering SelectAllFields();        
+        IOrdering SelectAllFields();
+
+        /// <summary>
+        /// Set where to continue searching from
+        /// </summary>
+        /// <param name="searchAfter">Search After</param>
+        /// <returns></returns>
+        IOrdering SetSearchAfter(SearchAfter searchAfter);
     }
 }

src/Examine.Core/Search/IQuery.cs

@@ -134,5 +134,15 @@
         /// <param name="maxInclusive"></param>
         /// <returns></returns>
         IBooleanOperation RangeQuery<T>(string[] fields, T? min, T? max, bool minInclusive = true, bool maxInclusive = true) where T : struct;
+
+        /// <summary>
+        /// Query for drill-down over facet categories. Call dimensions.Add() for each group of categories to drill-down over
+        /// </summary>
+        /// <param name="baseQuery">Base Query to Drill Down on</param>
+        /// <param name="dimensions">Facet Dimensions to Drill Down</param>
+        /// <param name="drillSideways">Facet Dimensions to Drill Sideways</param>
+        /// <param name="defaultOp">Base Query default Op</param>
+        /// <returns></returns>
+        IOrdering DrillDownQuery(Action<IDrillDownQueryDimensions> dimensions, Func<INestedQuery, INestedBooleanOperation>? baseQuery = null, Action<IDrillSideways>? drillSideways = null, BooleanOperation defaultOp = BooleanOperation.Or);
     }
 }

src/Examine.Core/Search/SearchAfter.cs

@@ -0,0 +1,22 @@
+namespace Examine.Search
+{
+    /// <summary>
+    /// Options for Searching After. Used for efficent deep paging.
+    /// </summary>
+    public class SearchAfter
+    {
+        /// <summary>
+        /// Constructor
+        /// </summary>
+        /// <param name="searchAfter">String representing the search after value</param>
+        public SearchAfter(string searchAfter)
+        {
+            Value = searchAfter;
+        }
+
+        /// <summary>
+        /// String representing the search after value
+        /// </summary>
+        public string Value { get; }
+    }
+}

src/Examine.Lucene/Indexing/FullTextType.cs

@@ -11,6 +11,7 @@
 using Lucene.Net.Documents;
 using Lucene.Net.Facet;
 using Lucene.Net.Facet.SortedSet;
+using Lucene.Net.Facet.Taxonomy;
 using Lucene.Net.Index;
 using Lucene.Net.Search;
 using Microsoft.Extensions.Logging;
@@ -134,7 +135,15 @@ protected override void AddSingleValue(Document doc, object value)
                         Field.Store.YES));
                 }
 
-                if (_isFacetable && _taxonomyIndex)
+                if (_isFacetable && _taxonomyIndex && value is IFacetLabel taxonomyFacetLabel)
+                {
+                    doc.Add(new FacetField(taxonomyFacetLabel.Components[0], taxonomyFacetLabel.Components.AsSpan().Slice(1).ToArray()));
+                }
+                else if (_isFacetable && !_taxonomyIndex && value is IFacetLabel facetLabel)
+                {
+                    doc.Add(new SortedSetDocValuesFacetField(facetLabel.Components[0], facetLabel.Components[1]));
+                }
+                else if(_isFacetable && _taxonomyIndex)
                 {
                     doc.Add(new FacetField(FieldName, str));
                 }

src/Examine.Lucene/Search/IFacetExtractionContext.cs

@@ -1,4 +1,5 @@
 using Lucene.Net.Facet;
+using Lucene.Net.Facet.SortedSet;
 
 namespace Examine.Lucene.Search
 {
@@ -22,6 +23,16 @@ public interface IFacetExtractionContext
         /// </summary>
         ISearcherReference SearcherReference { get; }
 
+        /// <summary>
+        /// SortedSetReaderState (Non taxonomy indexed)
+        /// </summary>
+        SortedSetDocValuesReaderState? SortedSetReaderState { get; }
+
+        /// <summary>
+        /// Drill Sideways Result Facets
+        /// </summary>
+        Facets? DrillSidewaysResultFacets { get; }
+
         /// <summary>
         /// Get the facet counts for the faceted field
         /// </summary>

src/Examine.Lucene/Search/LuceneBooleanOperation.cs

@@ -1,7 +1,6 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
-using Examine.Lucene.Providers;
 using Examine.Search;
 using Lucene.Net.Search;
 
@@ -82,5 +81,12 @@ public override IQueryExecutor WithFacets(Action<IFacetOperations> facets)
             facets.Invoke(luceneFacetOperation);
             return luceneFacetOperation;
         }
+
+        /// <inheritdoc/>
+        public override IOrdering SetSearchAfter(SearchAfter searchAfter)
+        {
+            _search.SetSearchAfter(searchAfter);
+            return this;
+        }
     }
 }

src/Examine.Lucene/Search/LuceneBooleanOperationBase.cs

@@ -118,6 +118,42 @@ protected internal LuceneBooleanOperationBase Op(
             return _search.LuceneQuery(_search.Queries.Pop(), outerOp);
         }
 
+        /// <summary>
+        /// Used to add a operation
+        /// </summary>
+        /// <param name="baseQueryBuilder">Function that the base query will be passed into to create the outer query</param>
+        /// <param name="inner"></param>
+        /// <param name="outerOp"></param>
+        /// <param name="defaultInnerOp"></param>
+        /// <returns></returns>
+        protected internal LuceneBooleanOperationBase OpBaseQuery(
+            Func<Query,Query> baseQueryBuilder,
+            Func<INestedQuery, INestedBooleanOperation> inner,
+            BooleanOperation outerOp,
+            BooleanOperation? defaultInnerOp = null)
+        {
+            _search.Queries.Push(new BooleanQuery());
+
+            //change the default inner op if specified
+            var currentOp = _search.BooleanOperation;
+            if (defaultInnerOp != null)
+            {
+                _search.BooleanOperation = defaultInnerOp.Value;
+            }
+
+            //run the inner search
+            inner(_search);
+
+            //reset to original op if specified
+            if (defaultInnerOp != null)
+            {
+                _search.BooleanOperation = currentOp;
+            }
+            var baseBoolQuery = _search.Queries.Pop();
+            var baseQuery = baseQueryBuilder(baseBoolQuery);
+            return _search.LuceneQuery(baseQuery, outerOp);
+        }
+
         /// <inheritdoc/>
         public abstract ISearchResults Execute(QueryOptions? options = null);
 
@@ -138,5 +174,8 @@ protected internal LuceneBooleanOperationBase Op(
 
         /// <inheritdoc/>
         public abstract IQueryExecutor WithFacets(Action<IFacetOperations> facets);
+
+        /// <inheritdoc/>
+        public abstract IOrdering SetSearchAfter(SearchAfter searchAfter);
     }
 }

src/Examine.Lucene/Search/LuceneDrillDownQueryDimensionBase.cs

@@ -0,0 +1,30 @@
+using Lucene.Net.Facet;
+
+namespace Examine.Lucene.Search
+{
+    /// <summary>
+    /// Lucene DrillDown Query Dimensions base
+    /// </summary>
+    public abstract class LuceneDrillDownQueryDimensionBase
+    {
+        /// <summary>
+        /// Constructor
+        /// </summary>
+        /// <param name="dimensionName">Dimension Name</param>
+        public LuceneDrillDownQueryDimensionBase(string dimensionName)
+        {
+            DimensionName = dimensionName;
+        }
+
+        /// <summary>
+        /// Dimension Name
+        /// </summary>
+        public string DimensionName { get; }
+
+        /// <summary>
+        /// Add the dimension to the Drill-down Query
+        /// </summary>
+        /// <param name="drillDownQuery"></param>
+        public abstract void Apply(DrillDownQuery drillDownQuery);
+    }
+}