added support for Top Hits aggregation

Author: Mpdreamz

src/Nest/Domain/Aggregations/AggregationsHelper.cs

@@ -81,6 +81,11 @@ public PercentilesMetric PercentilesRank(string key)
 			return this.TryGet<PercentilesMetric>(key);
 		}
 
+		public TopHitsMetric TopHitsMetric(string key)
+		{
+			return this.TryGet<TopHitsMetric>(key);
+		}
+
 		public SingleBucket Global(string key)
 		{
 			return this.TryGet<SingleBucket>(key);

src/Nest/Domain/Aggregations/TopHitsMetric.cs

@@ -0,0 +1,41 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+
+namespace Nest
+{
+	public class TopHitsMetric : IMetricAggregation
+	{
+		private IEnumerable<JObject> _hits;
+
+		public TopHitsMetric()
+		{
+		}
+		
+		internal TopHitsMetric(IEnumerable<JObject> hits)
+		{
+			_hits = hits;
+		}
+
+		public long Total { get; set; }
+		public double? MaxScore { get; set; }
+
+		public IEnumerable<Hit<T>> Hits<T>(JsonSerializer serializer = null) where T : class
+		{
+			if (serializer != null)
+				return _hits.Select(h => h.ToObject<Hit<T>>(serializer));
+			return _hits.Select(h => h.ToObject<Hit<T>>());
+		}
+
+		public IEnumerable<T> Documents<T>(JsonSerializer serializer = null) where T : class
+		{
+			return this.Hits<T>(serializer).Select(h => h.Source);
+		}
+
+
+	}
+
+}

src/Nest/Domain/Hit/Hit.cs

@@ -12,7 +12,7 @@ public interface IHit<out T> where T : class
 		IFieldSelection<T> Fields { get; }
 		T Source { get; }
 		string Index { get; }
-		double Score { get; }
+		double? Score { get; }
 		string Type { get; }
 		string Version { get; }
 		string Id { get; }
@@ -36,7 +36,7 @@ public class Hit<T> : IHit<T>
 		[JsonProperty(PropertyName = "_index")]
 		public string Index { get; internal set; }
 		[JsonProperty(PropertyName = "_score")]
-		public double Score { get; internal set; }
+		public double? Score { get; internal set; }
 		[JsonProperty(PropertyName = "_type")]
 		public string Type { get; internal set; }
 		[JsonProperty(PropertyName = "_version")]

src/Nest/Nest.csproj

@@ -106,6 +106,7 @@
     <Compile Include="Domain\Aggregations\AggregationsHelper.cs" />
     <Compile Include="Domain\Aggregations\Bucket.cs" />
     <Compile Include="Domain\Aggregations\BucketAggregationBase.cs" />
+    <Compile Include="Domain\Aggregations\TopHitsMetric.cs" />
     <Compile Include="Domain\Aggregations\GeoBoundsMetric.cs" />
     <Compile Include="Domain\Aggregations\HistogramItem.cs" />
     <Compile Include="Domain\Aggregations\ExtendedStatsMetric.cs" />

src/Nest/Resolvers/Converters/Aggregations/AggregationConverter.cs

@@ -59,12 +59,27 @@ private IAggregation ReadAggregation(JsonReader reader, JsonSerializer serialize
 					return GetSingleBucketAggregation(reader, serializer);
 				case "bounds":
 					return GetGeoBoundsMetricAggregation(reader, serializer);
+				case "hits":
+					return GetHitsAggregation(reader, serializer);
 				default:
 					return null; 
 
 			}
 		}
 
+		private IAggregation GetHitsAggregation(JsonReader reader, JsonSerializer serializer)
+		{
+			reader.Read();
+			var o = JObject.Load(reader);
+			if (o == null)
+				return null;
+
+			var total = o["total"].ToObject<long>();
+			var maxScore = o["max_score"].ToObject<double?>();
+			var hits = o["hits"].Children().OfType<JObject>().Select(s=>s);
+			return new TopHitsMetric(hits) { Total = total, MaxScore = maxScore };
+		}
+
 		private IAggregation GetGeoBoundsMetricAggregation(JsonReader reader, JsonSerializer serializer)
 		{
 			reader.Read();
@@ -369,15 +384,15 @@ public IAggregation GetRangeAggregation(JsonReader reader, JsonSerializer serial
 						break;
 				}
 			}
-				var bucket = new RangeItem
-				{
-					Key = key,
-					From = fromDouble,
-					To = toDouble,
-					DocCount = docCount.GetValueOrDefault(),
-					FromAsString = fromAsString,
-					ToAsString = toAsString
-				};
+			var bucket = new RangeItem
+			{
+				Key = key,
+				From = fromDouble,
+				To = toDouble,
+				DocCount = docCount.GetValueOrDefault(),
+				FromAsString = fromAsString,
+				ToAsString = toAsString
+			};
 
 			bucket.Aggregations = this.GetNestedAggregations(reader, serializer);
 			return bucket;

src/Tests/Nest.Tests.Integration/Aggregations/MetricAggregationTests.cs

@@ -1,4 +1,5 @@
 using System.Linq;
+using Elasticsearch.Net;
 using FluentAssertions;
 using Nest.Tests.MockData.Domain;
 using NUnit.Framework;
@@ -187,6 +188,21 @@ public void TopHits()
 					)
 				)
 			);
+
+			results.IsValid.Should().BeTrue();
+
+			var topCountries = results.Aggs.Terms("top-countries").Items;
+			foreach(var topCountry in topCountries)
+			{
+				var topHits = topCountry.TopHitsMetric("top-country-hits");
+				topHits.Should().NotBeNull();
+				topHits.Total.Should().BeGreaterThan(0);
+				var hits = topHits.Hits<ElasticsearchProject>();
+				hits.Should().NotBeEmpty().And.NotContain(h=> h.Id.IsNullOrEmpty() || h.Index.IsNullOrEmpty());
+				topHits.Documents<ElasticsearchProject>().Should().NotBeEmpty();
+
+			}
+
 		}
 	}
 }