Append date_optional_time format when extended_bounds are specified

See #1784

Author: russcam

Diff for: src/Nest/Aggregations/Bucket/DateHistogram/DateHistogramAggregation.cs

@@ -48,11 +48,25 @@ public interface IDateHistogramAggregation : IBucketAggregation
 
 	public class DateHistogramAggregation : BucketAggregationBase, IDateHistogramAggregation
 	{
+		private string _format;
 		public Field Field { get; set; }
 		public IScript Script { get; set; }
 		public IDictionary<string, object> Params { get; set; }
 		public Union<DateInterval, Time> Interval { get; set; }
-		public string Format { get; set; }
+
+		public string Format
+		{
+			get
+			{
+				return !string.IsNullOrEmpty(_format) && 
+					!_format.Contains("date_optional_time") &&
+					ExtendedBounds != null
+					? _format + "||date_optional_time"
+					: _format;
+			}
+			set { _format = value; }
+		}
+
 		public int? MinimumDocumentCount { get; set; }
 		public string TimeZone { get; set; }
 		public int? Factor { get; set; }
@@ -73,6 +87,7 @@ public class DateHistogramAggregationDescriptor<T>
 			, IDateHistogramAggregation
 		where T : class
 	{
+		private string _format;
 		Field IDateHistogramAggregation.Field { get; set; }
 
 		IScript IDateHistogramAggregation.Script { get; set; }
@@ -81,7 +96,18 @@ public class DateHistogramAggregationDescriptor<T>
 
 		Union<DateInterval, Time> IDateHistogramAggregation.Interval { get; set; }
 
-		string IDateHistogramAggregation.Format { get; set; }
+		string IDateHistogramAggregation.Format
+		{
+			get
+			{
+				return !string.IsNullOrEmpty(_format) &&
+					!_format.Contains("date_optional_time") &&
+					Self.ExtendedBounds != null
+					? _format + "||date_optional_time"
+					: _format;
+			}
+			set { _format = value; }
+		}
 
 		int? IDateHistogramAggregation.MinimumDocumentCount { get; set; }
 

Diff for: src/Tests/Aggregations/Bucket/DateHistogram/DateHistogramAggregationUsageTests.cs

@@ -14,8 +14,8 @@ namespace Tests.Aggregations.Bucket.DateHistogram
 	 * The main difference is that the interval can be specified by date/time expressions.
 	 *
 	 * When specifying a format and extended_bounds, in order for Elasticsearch to be able to parse
-	 * the serialized DateTimes extended_bounds correctly, the date_optional_time format should
-	 * also be specified as an additional format.
+	 * the serialized DateTimes of extended_bounds correctly, the date_optional_time format is included
+	 * as part of the format value.
 	 *
 	 * Be sure to read the elasticsearch documentation {ref}/search-aggregations-bucket-datehistogram-aggregation.html[on this subject here]
 	*/
@@ -72,7 +72,7 @@ public DateHistogramAggregationUsageTests(ReadOnlyCluster i, EndpointUsage usage
 					.Field(p => p.StartedOn)
 					.Interval(DateInterval.Month)
 					.MinimumDocumentCount(2)
-					.Format("yyyy-MM-dd'T'HH:mm:ss||date_optional_time")
+					.Format("yyyy-MM-dd'T'HH:mm:ss")
 					.ExtendedBounds(FixedDate.AddYears(-1), FixedDate.AddYears(1))
 					.Order(HistogramOrder.CountAscending)
 					.Missing(FixedDate)
@@ -96,7 +96,7 @@ public DateHistogramAggregationUsageTests(ReadOnlyCluster i, EndpointUsage usage
 					Field = Field<Project>(p => p.StartedOn),
 					Interval = DateInterval.Month,
 					MinimumDocumentCount = 2,
-					Format = "yyyy-MM-dd'T'HH:mm:ss||date_optional_time",
+					Format = "yyyy-MM-dd'T'HH:mm:ss",
 					ExtendedBounds = new ExtendedBounds<DateTime>
 					{
 						Minimum = FixedDate.AddYears(-1),