Add a composite aggregation

Author: Jon Dalberg

lib/elasticsearch/dsl/search/aggregations/composite.rb

@@ -0,0 +1,61 @@
+# Licensed to Elasticsearch B.V. under one or more contributor
+# license agreements. See the NOTICE file distributed with
+# this work for additional information regarding copyright
+# ownership. Elasticsearch B.V. licenses this file to you under
+# the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#	http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+module Elasticsearch
+    module DSL
+      module Search
+        module Aggregations
+          #
+          # A multi-bucket aggregation that creates composite buckets from different sources.
+          #
+          # @example
+          #
+          #  search do
+          #    aggregation :things do
+          #      composite do
+          #        size 2000
+          #        sources [
+          #          { thing1: { terms: { field: 'thing1.field1' } } },
+          #          { thing2: { terms: { field: 'thing2.field2' } } }
+          #        ]
+          #        after after_key
+          #      end
+          #    end
+          #  end
+          #
+          # @see https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-composite-aggregation.html
+          #
+          class Composite
+            include BaseAggregationComponent
+  
+            option_method :size
+            option_method :sources
+            option_method :after
+  
+            def to_hash(_options={})
+              super
+              # remove :after if no value is given
+              @hash[self.name.to_sym].delete(:after) if @hash[self.name.to_sym][:after].nil?
+  
+              @hash
+            end
+          end
+        end
+      end
+    end
+  end
+end