Add histogram datatype

src/Nest/Mapping/DynamicTemplate/SingleMapping.cs

@@ -51,6 +51,10 @@ public IProperty IpRange(Func<IpRangePropertyDescriptor<T>, IIpRangeProperty> se
 		public IProperty Join(Func<JoinPropertyDescriptor<T>, IJoinProperty> selector) =>
 			selector?.Invoke(new JoinPropertyDescriptor<T>());
 
+		/// <inheritdoc />
+		public IProperty Histogram(Func<HistogramPropertyDescriptor<T>, IHistogramProperty> selector) =>
+			selector?.Invoke(new HistogramPropertyDescriptor<T>());
+
 		public IProperty Keyword(Func<KeywordPropertyDescriptor<T>, IKeywordProperty> selector) =>
 			selector?.Invoke(new KeywordPropertyDescriptor<T>());
 

src/Nest/Mapping/Types/FieldType.cs

@@ -138,6 +138,9 @@ public enum FieldType
 		Flattened,
 
 		[EnumMember(Value = "shape")]
-		Shape
+		Shape,
+
+		[EnumMember(Value = "histogram")]
+		Histogram
 	}
 }

src/Nest/Mapping/Types/Properties.cs

@@ -97,6 +97,9 @@ TReturnType Nested<TChild>(Func<NestedPropertyDescriptor<T, TChild>, INestedProp
 		TReturnType IpRange(Func<IpRangePropertyDescriptor<T>, IIpRangeProperty> selector);
 
 		TReturnType Join(Func<JoinPropertyDescriptor<T>, IJoinProperty> selector);
+
+		/// <inheritdoc cref="IHistogramProperty"/>
+		TReturnType Histogram(Func<HistogramPropertyDescriptor<T>, IHistogramProperty> selector);
 	}
 
 	public partial class PropertiesDescriptor<T> where T : class
@@ -174,6 +177,9 @@ public PropertiesDescriptor<T> Object<TChild>(Func<ObjectTypeDescriptor<T, TChil
 		/// <inheritdoc cref="IFlattenedProperty"/>
 		public PropertiesDescriptor<T> Flattened(Func<FlattenedPropertyDescriptor<T>, IFlattenedProperty> selector) => SetProperty(selector);
 
+		/// <inheritdoc cref="IHistogramProperty"/>
+		public PropertiesDescriptor<T> Histogram(Func<HistogramPropertyDescriptor<T>, IHistogramProperty> selector) => SetProperty(selector);
+
 		public PropertiesDescriptor<T> Custom(IProperty customType) => SetProperty(customType);
 
 		private PropertiesDescriptor<T> SetProperty<TDescriptor, TInterface>(Func<TDescriptor, TInterface> selector)

src/Nest/Mapping/Types/PropertyFormatter.cs

@@ -93,6 +93,7 @@ public IProperty Deserialize(ref JsonReader reader, IJsonFormatterResolver forma
 				case FieldType.RankFeature: return Deserialize<RankFeatureProperty>(ref segmentReader, formatterResolver);
 				case FieldType.RankFeatures: return Deserialize<RankFeaturesProperty>(ref segmentReader, formatterResolver);
 				case FieldType.Flattened: return Deserialize<FlattenedProperty>(ref segmentReader, formatterResolver);
+				case FieldType.Histogram: return Deserialize<HistogramProperty>(ref segmentReader, formatterResolver);
 				case FieldType.None:
 					// no "type" field in the property mapping, or FieldType enum could not be parsed from typeString
 					return Deserialize<ObjectProperty>(ref segmentReader, formatterResolver);
@@ -198,6 +199,9 @@ public void Serialize(ref JsonWriter writer, IProperty value, IJsonFormatterReso
 				case IFlattenedProperty flattenedProperty:
 					Serialize(ref writer, flattenedProperty, formatterResolver);
 					break;
+				case IHistogramProperty histogramProperty:
+					Serialize(ref writer, histogramProperty, formatterResolver);
+					break;
 				case IGenericProperty genericProperty:
 					Serialize(ref writer, genericProperty, formatterResolver);
 					break;

src/Nest/Mapping/Types/Specialized/Histogram/HistogramAttribute.cs

@@ -0,0 +1,18 @@
+namespace Nest
+{
+	public class HistogramAttribute : ElasticsearchPropertyAttributeBase, IHistogramProperty
+	{
+		public HistogramAttribute() : base(FieldType.Histogram) { }
+
+		/// <inheritdoc cref="IHistogramProperty.IgnoreMalformed"/>
+		public bool IgnoreMalformed
+		{
+			get => Self.IgnoreMalformed.GetValueOrDefault();
+			set => Self.IgnoreMalformed = value;
+		}
+
+		bool? IHistogramProperty.IgnoreMalformed { get; set; }
+
+		private IHistogramProperty Self => this;
+	}
+}

src/Nest/Mapping/Types/Specialized/Histogram/HistogramProperty.cs

@@ -0,0 +1,46 @@
+using System.Diagnostics;
+using System.Runtime.Serialization;
+using Elasticsearch.Net.Utf8Json;
+
+namespace Nest
+{
+	/// <summary>
+	/// A field to store pre-aggregated numerical data representing a histogram.
+	/// <para />
+	/// Available in Elasticsearch 7.6.0+ with at least basic license level
+	/// </summary>
+	[InterfaceDataContract]
+	public interface IHistogramProperty : IProperty
+	{
+		/// <summary>
+		/// Whether to ignore malformed input values.
+		/// </summary>
+		[DataMember(Name = "ignore_malformed")]
+		bool? IgnoreMalformed { get; set; }
+	}
+
+	/// <inheritdoc cref="IHistogramProperty"/>
+	[DebuggerDisplay("{DebugDisplay}")]
+	public class HistogramProperty : PropertyBase, IHistogramProperty
+	{
+		public HistogramProperty() : base(FieldType.Histogram) { }
+
+		/// <inheritdoc />
+		public bool? IgnoreMalformed { get; set; }
+	}
+
+	/// <inheritdoc cref="IHistogramProperty"/>
+	[DebuggerDisplay("{DebugDisplay}")]
+	public class HistogramPropertyDescriptor<T>
+		: PropertyDescriptorBase<HistogramPropertyDescriptor<T>, IHistogramProperty, T>, IHistogramProperty
+		where T : class
+	{
+		bool? IHistogramProperty.IgnoreMalformed { get; set; }
+
+		public HistogramPropertyDescriptor() : base(FieldType.Histogram) { }
+
+		/// <inheritdoc cref="IHistogramProperty.IgnoreMalformed"/>
+		public HistogramPropertyDescriptor<T> IgnoreMalformed(bool? ignoreMalformed = true) =>
+			Assign(ignoreMalformed, (a, v) => a.IgnoreMalformed = v);
+	}
+}

src/Nest/Mapping/Visitor/IMappingVisitor.cs

@@ -61,6 +61,8 @@ public interface IMappingVisitor
 		void Visit(ISearchAsYouTypeProperty property);
 
 		void Visit(IFlattenedProperty property);
+
+		void Visit(IHistogramProperty property);
 	}
 
 	public class NoopMappingVisitor : IMappingVisitor
@@ -124,5 +126,7 @@ public virtual void Visit(IRankFeaturesProperty property) { }
 		public virtual void Visit(ISearchAsYouTypeProperty property) { }
 
 		public virtual void Visit(IFlattenedProperty property) { }
+
+		public virtual void Visit(IHistogramProperty property) { }
 	}
 }

src/Nest/Mapping/Visitor/IPropertyVisitor.cs

@@ -60,6 +60,8 @@ public interface IPropertyVisitor
 
 		void Visit(IFlattenedProperty type, PropertyInfo propertyInfo, ElasticsearchPropertyAttributeBase attribute);
 
+		void Visit(IHistogramProperty type, PropertyInfo propertyInfo, ElasticsearchPropertyAttributeBase attribute);
+
 		IProperty Visit(PropertyInfo propertyInfo, ElasticsearchPropertyAttributeBase attribute);
 
 		bool SkipProperty(PropertyInfo propertyInfo, ElasticsearchPropertyAttributeBase attribute);

src/Nest/Mapping/Visitor/MappingWalker.cs

@@ -182,8 +182,6 @@ public void Accept(IProperties properties)
 							Accept(t.Fields);
 						});
 						break;
-					case FieldType.None:
-						continue;
 					case FieldType.Percolator:
 						Visit<IPercolatorProperty>(field, t => { _visitor.Visit(t); });
 						break;
@@ -253,6 +251,14 @@ public void Accept(IProperties properties)
 							_visitor.Visit(t);
 						});
 						break;
+					case FieldType.Histogram:
+						Visit<IHistogramProperty>(field, t =>
+						{
+							_visitor.Visit(t);
+						});
+						break;
+					case FieldType.None:
+						continue;
 				}
 			}
 		}

src/Nest/Mapping/Visitor/NoopPropertyVisitor.cs

@@ -60,6 +60,8 @@ public virtual void Visit(IKeywordProperty type, PropertyInfo propertyInfo, Elas
 
 		public virtual void Visit(IFlattenedProperty type, PropertyInfo propertyInfo, ElasticsearchPropertyAttributeBase attribute) { }
 
+		public virtual void Visit(IHistogramProperty type, PropertyInfo propertyInfo, ElasticsearchPropertyAttributeBase attribute) { }
+
 		public virtual IProperty Visit(PropertyInfo propertyInfo, ElasticsearchPropertyAttributeBase attribute) => null;
 
 		public void Visit(IProperty type, PropertyInfo propertyInfo, ElasticsearchPropertyAttributeBase attribute)
@@ -144,6 +146,9 @@ public void Visit(IProperty type, PropertyInfo propertyInfo, ElasticsearchProper
 				case IRankFeaturesProperty rankFeatures:
 					Visit(rankFeatures, propertyInfo, attribute);
 					break;
+				case IHistogramProperty histogram:
+					Visit(histogram, propertyInfo, attribute);
+					break;
 			}
 		}
 	}

tests/Tests/Indices/MappingManagement/GetMapping/GetMappingApiTest.cs

@@ -211,6 +211,8 @@ internal class TestVisitor : IMappingVisitor
 
 		public void Visit(IFlattenedProperty property) => Increment("flattened");
 
+		public void Visit(IHistogramProperty property) => Increment("histogram");
+
 		private void Increment(string key)
 		{
 			if (!Counts.ContainsKey(key)) Counts.Add(key, 0);

tests/Tests/Mapping/Types/Specialized/Histogram/HistogramAttributeTests.cs

@@ -0,0 +1,32 @@
+using Nest;
+
+namespace Tests.Mapping.Types.Specialized.Histogram
+{
+	public class HistogramTest
+	{
+		[Histogram(IgnoreMalformed = true)]
+		public string Full { get; set; }
+
+		[Histogram]
+		public string Minimal { get; set; }
+	}
+
+	public class HistogramAttributeTests : AttributeTestsBase<HistogramTest>
+	{
+		protected override object ExpectJson => new
+		{
+			properties = new
+			{
+				full = new
+				{
+					type = "histogram",
+					ignore_malformed = true
+				},
+				minimal = new
+				{
+					type = "histogram"
+				}
+			}
+		};
+	}
+}

tests/Tests/Mapping/Types/Specialized/Histogram/HistogramPropertyTests.cs

@@ -0,0 +1,44 @@
+using System;
+using Elastic.Xunit.XunitPlumbing;
+using Nest;
+using Tests.Core.ManagedElasticsearch.Clusters;
+using Tests.Domain;
+using Tests.Framework.EndpointTests.TestState;
+
+namespace Tests.Mapping.Types.Specialized.Histogram
+{
+	[SkipVersion("<7.6.0", "Introduced in 7.6.0")]
+	public class HistogramPropertyTests : PropertyTestsBase
+	{
+		public HistogramPropertyTests(WritableCluster cluster, EndpointUsage usage) : base(cluster, usage) { }
+
+		protected override object ExpectJson => new
+		{
+			properties = new
+			{
+				name = new
+				{
+					type = "histogram",
+					ignore_malformed = true,
+				}
+			}
+		};
+
+		protected override Func<PropertiesDescriptor<Project>, IPromise<IProperties>> FluentProperties => f => f
+			.Histogram(s => s
+				.Name(p => p.Name)
+				.IgnoreMalformed()
+			);
+
+
+		protected override IProperties InitializerProperties => new Properties
+		{
+			{
+				"name", new HistogramProperty
+				{
+					IgnoreMalformed = true,
+				}
+			}
+		};
+	}
+}