Add support for rate aggregation

docs/aggregations.asciidoc

@@ -56,6 +56,8 @@ The values are typically extracted from the fields of the document (using the fi
 
 * <<percentiles-aggregation-usage,Percentiles Aggregation Usage>>
 
+* <<rate-aggregation-usage,Rate Aggregation Usage>>
+
 * <<scripted-metric-aggregation-usage,Scripted Metric Aggregation Usage>>
 
 * <<stats-aggregation-usage,Stats Aggregation Usage>>
@@ -100,6 +102,8 @@ include::aggregations/metric/percentile-ranks/percentile-ranks-aggregation-usage
 
 include::aggregations/metric/percentiles/percentiles-aggregation-usage.asciidoc[]
 
+include::aggregations/metric/rate/rate-aggregation-usage.asciidoc[]
+
 include::aggregations/metric/scripted-metric/scripted-metric-aggregation-usage.asciidoc[]
 
 include::aggregations/metric/stats/stats-aggregation-usage.asciidoc[]

docs/aggregations/metric/rate/rate-aggregation-usage.asciidoc

@@ -0,0 +1,94 @@
+:ref_current: https://www.elastic.co/guide/en/elasticsearch/reference/7.11
+
+:github: https:/elastic/elasticsearch-net
+
+:nuget: https://www.nuget.org/packages
+
+////
+IMPORTANT NOTE
+==============
+This file has been generated from https:/elastic/elasticsearch-net/tree/7.x/src/Tests/Tests/Aggregations/Metric/Rate/RateAggregationUsageTests.cs. 
+If you wish to submit a PR for any spelling mistakes, typos or grammatical errors for this file,
+please modify the original csharp file found at the link and submit the PR with that change. Thanks!
+////
+
+[[rate-aggregation-usage]]
+=== Rate Aggregation Usage
+
+A rate metrics aggregation can be used only inside a date_histogram and calculates a rate of documents or a field in each
+date_histogram bucket. The field values can be generated by a provided script or extracted from specific numeric or histogram fields in the documents.
+
+Be sure to read the Elasticsearch documentation on {ref_current}/search-aggregations-metrics-rate-aggregation.html[Rate Aggregation].
+
+==== Fluent DSL example
+
+[source,csharp]
+----
+a => a
+.DateHistogram("by_date", d => d
+ .Field(f => f.StartedOn)
+ .CalendarInterval(DateInterval.Month)
+ .Aggregations(a => a
+ .Rate("my_rate", m => m
+ .Field(p => p.NumberOfCommits)
+ .Unit(DateInterval.Month)
+ .Mode(RateMode.Sum)
+ )))
+----
+
+==== Object Initializer syntax example
+
+[source,csharp]
+----
+new DateHistogramAggregation("by_date")
+{
+ Field = Field<Project>(p => p.StartedOn),
+ CalendarInterval = DateInterval.Month,
+ Aggregations = new RateAggregation("my_rate", Field<Project>(p => p.NumberOfCommits))
+ {
+ Unit = DateInterval.Month,
+ Mode = RateMode.Sum
+ }
+}
+----
+
+[source,javascript]
+.Example json output
+----
+{
+ "by_date": {
+ "date_histogram": {
+ "field": "startedOn",
+ "calendar_interval": "month"
+ },
+ "aggs": {
+ "my_rate": {
+ "rate": {
+ "field": "numberOfCommits",
+ "unit": "month",
+ "mode": "sum"
+ }
+ }
+ }
+ }
+}
+----
+
+==== Handling Responses
+
+[source,csharp]
+----
+response.ShouldBeValid();
+
+var dateHistogram = response.Aggregations.DateHistogram("by_date");
+dateHistogram.Should().NotBeNull();
+dateHistogram.Buckets.Should().NotBeNull();
+dateHistogram.Buckets.Count.Should().BeGreaterThan(10);
+foreach (var item in dateHistogram.Buckets)
+{
+ var rate = item.Rate("my_rate");
+ rate.Should().NotBeNull();
+ rate.Value.Should().BeGreaterOrEqualTo(1);
+}
+----
+

src/Nest/Aggregations/AggregateDictionary.cs

@@ -206,6 +206,8 @@ public MultiBucketAggregate<RareTermsBucket<TKey>> RareTerms<TKey>(string key)
  };
  }
 
+ public ValueAggregate Rate(string key) => TryGet<ValueAggregate>(key);
+
  public MultiBucketAggregate<RareTermsBucket<string>> RareTerms(string key) => RareTerms<string>(key);
 
  public MultiBucketAggregate<RangeBucket> Range(string key) => GetMultiBucketAggregate<RangeBucket>(key);

src/Nest/Aggregations/AggregationContainer.cs

@@ -232,6 +232,9 @@ public interface IAggregationContainer
  [DataMember(Name = "rare_terms")]
  IRareTermsAggregation RareTerms { get; set; }
 
+ [DataMember(Name = "rate")]
+ IRateAggregation Rate { get; set; }
+
  [DataMember(Name = "reverse_nested")]
  IReverseNestedAggregation ReverseNested { get; set; }
 
@@ -388,6 +391,8 @@ public class AggregationContainer : IAggregationContainer
 
  public IRareTermsAggregation RareTerms { get; set; }
 
+ public IRateAggregation Rate { get; set; }
+
  public IReverseNestedAggregation ReverseNested { get; set; }
 
  public ISamplerAggregation Sampler { get; set; }
@@ -550,6 +555,8 @@ public class AggregationContainerDescriptor<T> : DescriptorBase<AggregationConta
 
  IRareTermsAggregation IAggregationContainer.RareTerms { get; set; }
 
+ IRateAggregation IAggregationContainer.Rate { get; set; }
+
  IReverseNestedAggregation IAggregationContainer.ReverseNested { get; set; }
 
  ISamplerAggregation IAggregationContainer.Sampler { get; set; }
@@ -724,6 +731,10 @@ Func<RareTermsAggregationDescriptor<T>, IRareTermsAggregation> selector
  ) =>
  _SetInnerAggregation(name, selector, (a, d) => a.RareTerms = d);
 
+ public AggregationContainerDescriptor<T> Rate(string name,
+ Func<RateAggregationDescriptor<T>, IRateAggregation> selector) =>
+ _SetInnerAggregation(name, selector, (a, d) => a.Rate = d);
+
  public AggregationContainerDescriptor<T> Stats(string name,
  Func<StatsAggregationDescriptor<T>, IStatsAggregation> selector
  ) =>

src/Nest/Aggregations/Metric/Rate/RateAggregate.cs

@@ -0,0 +1,79 @@
+// 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 Elasticsearch.Net;
+using Elasticsearch.Net.Utf8Json;
+
+namespace Nest
+{
+ [InterfaceDataContract]
+ [ReadAs(typeof(RateAggregation))]
+ public interface IRateAggregation : IMetricAggregation
+ {
+ /// <summary>
+ /// The <see cref="DateInterval"/> to use as the rate unit.
+ /// </summary>
+ [DataMember(Name = "unit")]
+ DateInterval Unit { get; set; }
+
+ /// <summary>
+ /// The mode to use in the rate calculation. By default, "sum" mode is used.
+ /// </summary>
+ /// <remarks>
+ /// The mode may be either "sum", where the rate calculates the sum of field values, or
+ /// "value_count", where the rate uses the number of values in the field.
+ /// </remarks>
+ [DataMember(Name = "mode")]
+ RateMode? Mode { get; set; }
+ }
+
+ public class RateAggregation : MetricAggregationBase, IRateAggregation
+ {
+ internal RateAggregation() { }
+ public RateAggregation(string name) : base(name, null) { }
+ public RateAggregation(string name, Field field) : base(name, field) { }
+
+ internal override void WrapInContainer(AggregationContainer c) => c.Rate = this;
+
+ /// <inheritdoc cref ="IRateAggregation.Unit"/>
+ public DateInterval Unit { get; set; }
+
+ /// <inheritdoc cref ="IRateAggregation.Mode"/>
+ public RateMode? Mode { get; set; }
+ }
+
+ public class RateAggregationDescriptor<T>
+ : MetricAggregationDescriptorBase<RateAggregationDescriptor<T>, IRateAggregation, T>, IRateAggregation
+ where T : class
+ {
+ DateInterval IRateAggregation.Unit { get; set; }
+
+ RateMode? IRateAggregation.Mode { get; set; }
+
+ /// <inheritdoc cref ="IRateAggregation.Unit"/>
+ public RateAggregationDescriptor<T> Unit(DateInterval dateInterval) =>
+ Assign(dateInterval, (a, v) => a.Unit = v);
+
+ /// <inheritdoc cref ="IRateAggregation.Mode"/>
+ public RateAggregationDescriptor<T> Mode(RateMode mode) =>
+ Assign(mode, (a, v) => a.Mode = v);
+ }
+
+ [StringEnum]
+ public enum RateMode
+ {
+ /// <summary>
+ /// TODO
+ /// </summary>
+ [EnumMember(Value = "sum")]
+ Sum,
+
+ /// <summary>
+ /// TODO
+ /// </summary>
+ [EnumMember(Value = "value_count")]
+ ValueCount
+ }
+}

src/Nest/Aggregations/Visitor/AggregationVisitor.cs

@@ -82,6 +82,8 @@ public interface IAggregationVisitor
 
  void Visit(IRareTermsAggregation aggregation);
 
+ void Visit(IRateAggregation aggregation);
+
  void Visit(ITermsAggregation aggregation);
 
  void Visit(ISignificantTermsAggregation aggregation);
@@ -241,6 +243,8 @@ public virtual void Visit(IRangeAggregation aggregation) { }
 
  public virtual void Visit(IRareTermsAggregation aggregation) { }
 
+ public virtual void Visit(IRateAggregation aggregation) { }
+
  public virtual void Visit(INestedAggregation aggregation) { }
 
  public virtual void Visit(INormalizeAggregation aggregation) { }

src/Nest/Aggregations/Visitor/AggregationWalker.cs

@@ -144,6 +144,7 @@ public void Walk(IAggregationContainer aggregation, IAggregationVisitor visitor)
  v.Visit(d);
  Accept(v, d.Aggregations);
  });
+ AcceptAggregation(aggregation.Rate, visitor, (v, d) => v.Visit(d));
  AcceptAggregation(aggregation.ReverseNested, visitor, (v, d) =>
  {
  v.Visit(d);