Add support for search ext parameter

CHANGELOG.md

@@ -12,6 +12,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Added support for `MinScore` on `ScriptScoreQuery` ([#624](https://github.com/opensearch-project/opensearch-net/pull/624))
 - Added support for the `Cat.PitSegments` and `Cat.SegmentReplication` APIs ([#527](https://github.com/opensearch-project/opensearch-net/pull/527))
 - Added support for serializing the `DateOnly` and `TimeOnly` types ([#734](https://github.com/opensearch-project/opensearch-net/pull/734))
+- Added support for the `Ext` parameter on `SearchRequest` ([#738](https://github.com/opensearch-project/opensearch-net/pull/738))
 
 ### Removed
 - Removed support for the `net461` target ([#256](https://github.com/opensearch-project/opensearch-net/pull/256))

src/OpenSearch.Client/Search/Search/SearchRequest.cs

@@ -214,6 +214,10 @@ public partial interface ISearchRequest : ITypedSearchRequest
 		/// </summary>
 		[DataMember(Name = "runtime_mappings")]
 		IRuntimeFields RuntimeFields { get; set; }
+
+        [DataMember(Name = "ext")]
+        [JsonFormatter(typeof(VerbatimDictionaryInterfaceKeysFormatter<string, object>))]
+        IDictionary<string, object> Ext { get; set; }
 	}
 
 	[ReadAs(typeof(SearchRequest<>))]
@@ -288,6 +292,8 @@ public partial class SearchRequest
 		public bool? Version { get; set; }
 		/// <inheritdoc />
 		public IRuntimeFields RuntimeFields { get; set; }
+        /// <inheritdoc />
+        public IDictionary<string, object> Ext { get; set; }
 
 		protected override HttpMethod HttpMethod =>
 			RequestState.RequestParameters?.ContainsQueryString("source") == true
@@ -347,6 +353,7 @@ public partial class SearchDescriptor<TInferDocument> where TInferDocument : cla
 		TrackTotalHits ISearchRequest.TrackTotalHits { get; set; }
 		bool? ISearchRequest.Version { get; set; }
 		IRuntimeFields ISearchRequest.RuntimeFields { get; set; }
+        IDictionary<string, object> ISearchRequest.Ext { get; set; }
 
 		protected sealed override void RequestDefaults(SearchRequestParameters parameters) => TypedKeys();
 
@@ -538,6 +545,14 @@ public SearchDescriptor<TInferDocument> PointInTime(Func<PointInTimeDescriptor,
 				if (a.PointInTime != null) a.RouteValues.Remove("index");
 			});
 
+        /// <inheritdoc cref="ISearchRequest.Ext"/>
+        public SearchDescriptor<TInferDocument> Ext(Func<FluentDictionary<string, object>, FluentDictionary<string, object>> selector) =>
+            Assign(selector(new FluentDictionary<string, object>()), (a, v) => a.Ext = v);
+
+        /// <inheritdoc cref="ISearchRequest.Ext"/>
+        public SearchDescriptor<TInferDocument> Ext(IDictionary<string, object> dictionary) =>
+            Assign(dictionary, (a, v) => a.Ext = v);
+
 		protected override string ResolveUrl(RouteValues routeValues, IConnectionSettingsValues settings) => base.ResolveUrl(routeValues, settings);
 	}
 }

tests/Tests/Search/Search/SearchApiTests.cs

@@ -75,7 +75,15 @@ public SearchApiTests(ReadOnlyCluster cluster, EndpointUsage usage) : base(clust
 						value = "Stable"
 					}
 				}
-			}
+			},
+            ext = new
+            {
+                personalize_request_parameters = new
+                {
+                    user_id = "<USER_ID>",
+                    context = new { DEVICE = "mobile phone"}
+                }
+            }
 		};
 
 		protected override int ExpectStatusCode => 200;
@@ -93,7 +101,13 @@ public SearchApiTests(ReadOnlyCluster cluster, EndpointUsage usage) : base(clust
 			)
 			.PostFilter(f => f
 				.Term(p => p.State, StateOfBeing.Stable)
-			);
+			)
+            .Ext(e => e
+                .Add("personalize_request_parameters", new Dictionary<string, object>
+                {
+                    ["user_id"] = "<USER_ID>",
+                    ["context"] = new Dictionary<string, string>{ ["DEVICE"] = "mobile phone" }
+                }));
 
 		protected override HttpMethod HttpMethod => HttpMethod.POST;
 
@@ -110,7 +124,18 @@ public SearchApiTests(ReadOnlyCluster cluster, EndpointUsage usage) : base(clust
 			{
 				Field = "state",
 				Value = "Stable"
-			})
+			}),
+            Ext = new Dictionary<string, object>
+            {
+                ["personalize_request_parameters"] = new Dictionary<string, object>
+                {
+                    ["user_id"] = "<USER_ID>",
+                    ["context"] = new Dictionary<string, string>
+                    {
+                        ["DEVICE"] = "mobile phone"
+                    }
+                }
+            }
 		};
 
 		protected override string UrlPath => $"/project/_search";