[Backport master] Support mapping runtime fields (#5234)

* Support mapping runtime fields
* Add missing XML comment for PIT
* Fixes for master namespaces

Co-authored-by: Steve Gordon <sgordon@hotmail.co.uk>

src/Nest/Indices/MappingManagement/PutMapping/PutMappingRequest.cs

@@ -56,6 +56,9 @@ public partial class PutMappingRequest
 		/// <inheritdoc />
 		public IRoutingField RoutingField { get; set; }
 
+		/// <inheritdoc />
+		public IRuntimeFields RuntimeFields { get; set; }
+
 		/// <inheritdoc />
 		public ISizeField SizeField { get; set; }
 
@@ -82,6 +85,7 @@ public partial class PutMappingDescriptor<TDocument> where TDocument : class
 		bool? ITypeMapping.NumericDetection { get; set; }
 		IProperties ITypeMapping.Properties { get; set; }
 		IRoutingField ITypeMapping.RoutingField { get; set; }
+		IRuntimeFields ITypeMapping.RuntimeFields { get; set; }
 		ISizeField ITypeMapping.SizeField { get; set; }
 		ISourceField ITypeMapping.SourceField { get; set; }
 
@@ -150,6 +154,10 @@ public PutMappingDescriptor<TDocument> SourceField(Func<SourceFieldDescriptor, I
 		public PutMappingDescriptor<TDocument> RoutingField(Func<RoutingFieldDescriptor<TDocument>, IRoutingField> routingFieldSelector) =>
 			Assign(routingFieldSelector, (a, v) => a.RoutingField = v?.Invoke(new RoutingFieldDescriptor<TDocument>()));
 
+		/// <inheritdoc cref="ITypeMapping.RuntimeFields" />
+		public PutMappingDescriptor<TDocument> RuntimeFields(Func<RuntimeFieldsDescriptor, IPromise<IRuntimeFields>> runtimeFieldsSelector) =>
+			Assign(runtimeFieldsSelector, (a, v) => a.RuntimeFields = v?.Invoke(new RuntimeFieldsDescriptor())?.Value);
+
 		/// <inheritdoc cref="ITypeMapping.FieldNamesField" />
 		public PutMappingDescriptor<TDocument> FieldNamesField(Func<FieldNamesFieldDescriptor<TDocument>, IFieldNamesField> fieldNamesFieldSelector) =>
 			Assign(fieldNamesFieldSelector, (a, v) => a.FieldNamesField = v.Invoke(new FieldNamesFieldDescriptor<TDocument>()));

src/Nest/Mapping/Mappings.cs

@@ -57,6 +57,8 @@ public abstract class ObsoleteMappingsBase : ITypeMapping
 		IProperties ITypeMapping.Properties { get => Wrapped.Properties; set => Wrapped.Properties = value; }
 		[DataMember(Name = "_routing")]
 		IRoutingField ITypeMapping.RoutingField { get => Wrapped.RoutingField; set => Wrapped.RoutingField = value; }
+		[DataMember(Name = "runtime")]
+		IRuntimeFields ITypeMapping.RuntimeFields { get => Wrapped.RuntimeFields; set => Wrapped.RuntimeFields = value; }
 		[DataMember(Name = "_size")]
 		ISizeField ITypeMapping.SizeField { get => Wrapped.SizeField; set => Wrapped.SizeField = value; }
 		[DataMember(Name = "_source")]

src/Nest/Mapping/RuntimeFields/RuntimeField.cs

@@ -0,0 +1,59 @@
+// Licensed to Elasticsearch B.V under one or more agreements.
+// Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information
+
+using System.Runtime.Serialization;
+using Nest.Utf8Json;
+
+namespace Nest
+{
+	[InterfaceDataContract]
+	[ReadAs(typeof(RuntimeField))]
+	public interface IRuntimeField
+	{
+		/// <summary>
+		/// Runtime fields with a type of date can accept the format parameter exactly as the date field type.
+		/// <see cref="DateFormat" />
+		/// </summary>
+		[DataMember(Name = "format")]
+		string Format { get; set; }
+
+		/// <summary>
+		/// The script to be evaluated for field calculation at search time.
+		/// </summary>
+		[DataMember(Name = "script")]
+		IStoredScript Script { get; set; }
+
+		/// <summary>
+		/// The datatype of the runtime field.
+		/// </summary>
+		[DataMember(Name = "type")]
+		FieldType Type { get; set; }
+	}
+
+	public class RuntimeField : IRuntimeField
+	{
+		/// <inheritdoc />
+		public string Format { get; set; }
+		/// <inheritdoc />
+		public IStoredScript Script { get; set; }
+		/// <inheritdoc />
+		public FieldType Type { get; set; }
+	}
+
+	public class RuntimeFieldDescriptor
+		: DescriptorBase<RuntimeFieldDescriptor, IRuntimeField>, IRuntimeField
+	{
+		public RuntimeFieldDescriptor(FieldType fieldType) => Self.Type = fieldType;
+
+		string IRuntimeField.Format { get; set; }
+		IStoredScript IRuntimeField.Script { get; set; }
+		FieldType IRuntimeField.Type { get; set; }
+
+		public RuntimeFieldDescriptor Format(string format) => Assign(format, (a, v) => a.Format = v);
+
+		public RuntimeFieldDescriptor Script(IStoredScript script) => Assign(script, (a, v) => a.Script = v);
+
+		public RuntimeFieldDescriptor Script(string source) => Assign(source, (a, v) => a.Script = new PainlessScript(source));
+	}
+}

src/Nest/Mapping/RuntimeFields/RuntimeFields.cs

@@ -0,0 +1,36 @@
+// Licensed to Elasticsearch B.V under one or more agreements.
+// Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information
+
+using System;
+using System.Collections.Generic;
+using Nest.Utf8Json;
+
+namespace Nest
+{
+	[JsonFormatter(typeof(VerbatimDictionaryKeysFormatter<RuntimeFields, IRuntimeFields, string, IRuntimeField>))]
+	public interface IRuntimeFields : IIsADictionary<string, IRuntimeField> { }
+
+	public class RuntimeFields : IsADictionaryBase<string, IRuntimeField>, IRuntimeFields
+	{
+		public RuntimeFields() { }
+
+		public RuntimeFields(IDictionary<string, IRuntimeField> container) : base(container) { }
+
+		public RuntimeFields(Dictionary<string, IRuntimeField> container) : base(container) { }
+
+		public void Add(string name, IRuntimeField runtimeField) => BackingDictionary.Add(name, runtimeField);
+	}
+
+	public class RuntimeFieldsDescriptor
+		: IsADictionaryDescriptorBase<RuntimeFieldsDescriptor, RuntimeFields, string, IRuntimeField>
+	{
+		public RuntimeFieldsDescriptor() : base(new RuntimeFields()) { }
+
+		public RuntimeFieldsDescriptor RuntimeField(string name, FieldType type, Func<RuntimeFieldDescriptor, IRuntimeField> selector) =>
+			Assign(name, selector?.Invoke(new RuntimeFieldDescriptor(type)));
+
+		public RuntimeFieldsDescriptor RuntimeField(string name, FieldType type) =>
+			Assign(name, new RuntimeFieldDescriptor(type));
+	}
+}

src/Nest/Mapping/TypeMapping.cs

@@ -96,6 +96,12 @@ public interface ITypeMapping
 		[DataMember(Name = "_routing")]
 		IRoutingField RoutingField { get; set; }
 
+		/// <summary>
+		/// Specifies runtime fields for the mapping.
+		/// </summary>
+		[DataMember(Name = "runtime")]
+		IRuntimeFields RuntimeFields { get; set; }
+
 		/// <summary>
 		/// If enabled, indexes the size in bytes of the original _source field.
 		/// Requires mapper-size plugin be installed
@@ -147,6 +153,9 @@ public class TypeMapping : ITypeMapping
 		/// <inheritdoc />
 		public IRoutingField RoutingField { get; set; }
 
+		/// <inheritdoc />
+		public IRuntimeFields RuntimeFields { get; set; }
+
 		/// <inheritdoc />
 		public ISizeField SizeField { get; set; }
 
@@ -171,6 +180,7 @@ public class TypeMappingDescriptor<T> : DescriptorBase<TypeMappingDescriptor<T>,
 		bool? ITypeMapping.NumericDetection { get; set; }
 		IProperties ITypeMapping.Properties { get; set; }
 		IRoutingField ITypeMapping.RoutingField { get; set; }
+		IRuntimeFields ITypeMapping.RuntimeFields { get; set; }
 		ISizeField ITypeMapping.SizeField { get; set; }
 		ISourceField ITypeMapping.SourceField { get; set; }
 
@@ -259,6 +269,10 @@ public TypeMappingDescriptor<T> DisableIndexField(bool? disabled = true) =>
 		public TypeMappingDescriptor<T> RoutingField(Func<RoutingFieldDescriptor<T>, IRoutingField> routingFieldSelector) =>
 			Assign(routingFieldSelector, (a, v) => a.RoutingField = v?.Invoke(new RoutingFieldDescriptor<T>()));
 
+		/// <inheritdoc cref="ITypeMapping.RuntimeFields" />
+		public TypeMappingDescriptor<T> RuntimeFields(Func<RuntimeFieldsDescriptor, IPromise<IRuntimeFields>> runtimeFieldsSelector) =>
+			Assign(runtimeFieldsSelector, (a, v) => a.RuntimeFields = v?.Invoke(new RuntimeFieldsDescriptor())?.Value);
+
 		/// <inheritdoc cref="ITypeMapping.FieldNamesField" />
 		public TypeMappingDescriptor<T> FieldNamesField(Func<FieldNamesFieldDescriptor<T>, IFieldNamesField> fieldNamesFieldSelector) =>
 			Assign(fieldNamesFieldSelector.Invoke(new FieldNamesFieldDescriptor<T>()), (a, v) => a.FieldNamesField = v);

src/Nest/Search/Search/SearchRequest.cs

@@ -168,6 +168,9 @@ public partial interface ISearchRequest : ITypedSearchRequest
 		[DataMember(Name = "version")]
 		bool? Version { get; set; }
 
+		/// <summary>
+		/// The <see cref="PointInTime"/> to search over.
+		/// </summary>
 		[DataMember(Name = "pit")]
 		IPointInTime PointInTime { get; set; }
 	}

tests/Tests/Indices/MappingManagement/PutMapping/PutMappingApiTest.cs

@@ -338,4 +338,61 @@ protected override LazyResponses ClientUsage() => Calls(
 			(client, r) => client.MapAsync(r)
 		);
 	}
+
+	[SkipVersion("<7.11.0", "Runtime fields introduced in 7.11.0")]
+	public class PutMappingWithRuntimeFieldsTests : ApiTestBase<ReadOnlyCluster, PutMappingResponse, IPutMappingRequest, PutMappingDescriptor<Project>, PutMappingRequest>
+	{
+		// These test serialisation only. Integration tests take place in RuntimeFieldsTests.cs
+
+		private const string ScriptValue = "emit(doc['@timestamp'].value.dayOfWeekEnum.getDisplayName(TextStyle.FULL, Locale.ROOT))";
+
+		public PutMappingWithRuntimeFieldsTests(ReadOnlyCluster cluster, EndpointUsage usage) : base(cluster, usage) { }
+
+		protected override HttpMethod HttpMethod => HttpMethod.PUT;
+
+		protected override string UrlPath => $"/{CallIsolatedValue}/_mapping";
+
+		protected override PutMappingRequest Initializer => new(CallIsolatedValue)
+		{
+			RuntimeFields = new RuntimeFields
+			{
+				{ "runtime_date", new RuntimeField { Type = FieldType.Date, Format = "yyyy-MM-dd" } },
+				{ "runtime_scripted", new RuntimeField { Type = FieldType.Keyword, Script = new PainlessScript(ScriptValue) } }
+			}
+		};
+
+		protected override Func<PutMappingDescriptor<Project>, IPutMappingRequest> Fluent => d => d
+			.Index(CallIsolatedValue)
+			.RuntimeFields(rtf => rtf
+				.RuntimeField("runtime_date", FieldType.Date, rf => rf.Format("yyyy-MM-dd"))
+				.RuntimeField("runtime_scripted", FieldType.Keyword, rf=> rf.Script(new PainlessScript(ScriptValue))));
+
+		protected override LazyResponses ClientUsage() => Calls(
+			(client, f) => client.Indices.PutMapping(f),
+			(client, f) => client.Indices.PutMappingAsync(f),
+			(client, r) => client.Indices.PutMapping(r),
+			(client, r) => client.Indices.PutMappingAsync(r)
+		);
+
+		protected override object ExpectJson => new
+		{
+			runtime = new
+			{
+				runtime_date = new
+				{
+					type = "date",
+					format = "yyyy-MM-dd"
+				},
+				runtime_scripted = new
+				{
+					type = "keyword",
+					script = new
+					{
+						lang = "painless",
+						source = ScriptValue
+					}
+				}
+			}
+		};
+	}
 }