Aggregations Refactor: Refactor Children Aggregation

core/src/main/java/org/elasticsearch/search/aggregations/bucket/children/ChildrenParser.java

@@ -67,9 +67,8 @@ public class ChildrenParser implements Aggregator.Parser {
         return new ParentToChildrenAggregator.Factory(aggregationName, childType);
     }
 
-    // NORELEASE implement this method when refactoring this aggregation
     @Override
     public AggregatorFactory[] getFactoryPrototypes() {
-        return null;
+        return new AggregatorFactory[] { new ParentToChildrenAggregator.Factory(null, null) };
     }
 }

core/src/main/java/org/elasticsearch/search/aggregations/bucket/children/ParentToChildrenAggregator.java

@@ -27,10 +27,14 @@ import org.apache.lucene.search.Query;
 import org.apache.lucene.search.Scorer;
 import org.apache.lucene.search.Weight;
 import org.apache.lucene.util.Bits;
+import org.elasticsearch.common.ParseField;
+import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.lease.Releasables;
 import org.elasticsearch.common.lucene.Lucene;
 import org.elasticsearch.common.util.LongArray;
 import org.elasticsearch.common.util.LongObjectPagedHashMap;
+import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.index.fielddata.plain.ParentChildIndexFieldData;
 import org.elasticsearch.index.mapper.DocumentMapper;
 import org.elasticsearch.index.mapper.internal.ParentFieldMapper;
@@ -44,21 +48,26 @@ import org.elasticsearch.search.aggregations.bucket.SingleBucketAggregator;
 import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
 import org.elasticsearch.search.aggregations.support.AggregationContext;
 import org.elasticsearch.search.aggregations.support.FieldContext;
+import org.elasticsearch.search.aggregations.support.ValueType;
 import org.elasticsearch.search.aggregations.support.ValuesSource;
+import org.elasticsearch.search.aggregations.support.ValuesSource.Bytes.ParentChild;
 import org.elasticsearch.search.aggregations.support.ValuesSourceAggregatorFactory;
 import org.elasticsearch.search.aggregations.support.ValuesSourceConfig;
-import org.elasticsearch.search.aggregations.support.ValuesSourceParser;
 import org.elasticsearch.search.aggregations.support.ValuesSourceType;
 
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
 
 // The RecordingPerReaderBucketCollector assumes per segment recording which isn't the case for this
 // aggregation, for this reason that collector can't be used
 public class ParentToChildrenAggregator extends SingleBucketAggregator {
 
+    static final ParseField TYPE_FIELD = new ParseField("type");
+
     private final String parentType;
     private final Weight childFilter;
     private final Weight parentFilter;
@@ -188,8 +197,14 @@ public class ParentToChildrenAggregator extends SingleBucketAggregator {
         private Query parentFilter;
         private Query childFilter;
 
+        /**
+         * @param name
+         *            the name of this aggregation
+         * @param childType
+         *            the type of children documents
+         */
         public Factory(String name, String childType) {
-            super(name, InternalChildren.TYPE, new ValuesSourceParser.Input<ValuesSource.Bytes.WithOrdinals.ParentChild>());
+            super(name, InternalChildren.TYPE, ValuesSourceType.BYTES, ValueType.STRING);
             this.childType = childType;
         }
 
@@ -247,5 +262,35 @@ public class ParentToChildrenAggregator extends SingleBucketAggregator {
             }
         }
 
+        @Override
+        protected XContentBuilder doXContentBody(XContentBuilder builder, Params params) throws IOException {
+            builder.field(TYPE_FIELD.getPreferredName(), childType);
+            return builder;
+        }
+
+        @Override
+        protected ValuesSourceAggregatorFactory<ParentChild> innerReadFrom(String name, ValuesSourceType valuesSourceType,
+                ValueType targetValueType, StreamInput in) throws IOException {
+            String childType = in.readString();
+            Factory factory = new Factory(name, childType);
+            return factory;
+        }
+
+        @Override
+        protected void innerWriteTo(StreamOutput out) throws IOException {
+            out.writeString(childType);
+        }
+
+        @Override
+        protected int innerHashCode() {
+            return Objects.hash(childType);
+        }
+
+        @Override
+        protected boolean innerEquals(Object obj) {
+            Factory other = (Factory) obj;
+            return Objects.equals(childType, other.childType);
+        }
+
     }
 }

core/src/test/java/org/elasticsearch/search/aggregations/bucket/ChildrenTests.java

@@ -0,0 +1,36 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch 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.
+ */
+
+package org.elasticsearch.search.aggregations.bucket;
+
+import org.elasticsearch.search.aggregations.BaseAggregationTestCase;
+import org.elasticsearch.search.aggregations.bucket.children.ParentToChildrenAggregator;
+import org.elasticsearch.search.aggregations.bucket.children.ParentToChildrenAggregator.Factory;
+
+public class ChildrenTests extends BaseAggregationTestCase<ParentToChildrenAggregator.Factory> {
+
+    @Override
+    protected Factory createTestAggregatorFactory() {
+        String name = randomAsciiOfLengthBetween(3, 20);
+        String childType = randomAsciiOfLengthBetween(5, 40);
+        Factory factory = new Factory(name, childType);
+        return factory;
+    }
+
+}