1 files changed, 167 insertions, 0 deletions
diff --git a/modules/parent-join/src/main/java/org/elasticsearch/join/aggregations/ChildrenAggregationBuilder.java b/modules/parent-join/src/main/java/org/elasticsearch/join/aggregations/ChildrenAggregationBuilder.java
new file mode 100644
index 0000000000..d04b1f0a66
--- /dev/null
+++ b/modules/parent-join/src/main/java/org/elasticsearch/join/aggregations/ChildrenAggregationBuilder.java
@@ -0,0 +1,167 @@
+/*
+ * 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.join.aggregations;
+
+import org.apache.lucene.search.Query;
+import org.elasticsearch.common.ParsingException;
+import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.common.io.stream.StreamOutput;
+import org.elasticsearch.common.xcontent.XContentBuilder;
+import org.elasticsearch.common.xcontent.XContentParser;
+import org.elasticsearch.index.fielddata.plain.ParentChildIndexFieldData;
+import org.elasticsearch.index.mapper.DocumentMapper;
+import org.elasticsearch.index.mapper.ParentFieldMapper;
+import org.elasticsearch.index.query.QueryParseContext;
+import org.elasticsearch.search.aggregations.AggregatorFactories.Builder;
+import org.elasticsearch.search.aggregations.AggregatorFactory;
+import org.elasticsearch.search.aggregations.support.FieldContext;
+import org.elasticsearch.search.aggregations.support.ValueType;
+import org.elasticsearch.search.aggregations.support.ValuesSource.Bytes.ParentChild;
+import org.elasticsearch.search.aggregations.support.ValuesSourceAggregationBuilder;
+import org.elasticsearch.search.aggregations.support.ValuesSourceAggregatorFactory;
+import org.elasticsearch.search.aggregations.support.ValuesSourceConfig;
+import org.elasticsearch.search.aggregations.support.ValuesSourceType;
+import org.elasticsearch.search.internal.SearchContext;
+
+import java.io.IOException;
+import java.util.Objects;
+
+public class ChildrenAggregationBuilder extends ValuesSourceAggregationBuilder<ParentChild, ChildrenAggregationBuilder> {
+    public static final String NAME = "children";
+
+    private String parentType;
+    private final String childType;
+    private Query parentFilter;
+    private Query childFilter;
+
+    /**
+     * @param name
+     *            the name of this aggregation
+     * @param childType
+     *            the type of children documents
+     */
+    public ChildrenAggregationBuilder(String name, String childType) {
+        super(name, ValuesSourceType.BYTES, ValueType.STRING);
+        if (childType == null) {
+            throw new IllegalArgumentException("[childType] must not be null: [" + name + "]");
+        }
+        this.childType = childType;
+    }
+
+    /**
+     * Read from a stream.
+     */
+    public ChildrenAggregationBuilder(StreamInput in) throws IOException {
+        super(in, ValuesSourceType.BYTES, ValueType.STRING);
+        childType = in.readString();
+    }
+
+    @Override
+    protected void innerWriteTo(StreamOutput out) throws IOException {
+        out.writeString(childType);
+    }
+
+    @Override
+    protected ValuesSourceAggregatorFactory<ParentChild, ?> innerBuild(SearchContext context,
+            ValuesSourceConfig<ParentChild> config, AggregatorFactory<?> parent, Builder subFactoriesBuilder) throws IOException {
+        return new ChildrenAggregatorFactory(name, config, parentType, childFilter, parentFilter, context, parent,
+                subFactoriesBuilder, metaData);
+    }
+
+    @Override
+    protected ValuesSourceConfig<ParentChild> resolveConfig(SearchContext context) {
+        ValuesSourceConfig<ParentChild> config = new ValuesSourceConfig<>(ValuesSourceType.BYTES);
+        DocumentMapper childDocMapper = context.mapperService().documentMapper(childType);
+
+        if (childDocMapper != null) {
+            ParentFieldMapper parentFieldMapper = childDocMapper.parentFieldMapper();
+            if (!parentFieldMapper.active()) {
+                throw new IllegalArgumentException("[children] no [_parent] field not configured that points to a parent type");
+            }
+            parentType = parentFieldMapper.type();
+            DocumentMapper parentDocMapper = context.mapperService().documentMapper(parentType);
+            if (parentDocMapper != null) {
+                parentFilter = parentDocMapper.typeFilter(context.getQueryShardContext());
+                childFilter = childDocMapper.typeFilter(context.getQueryShardContext());
+                ParentChildIndexFieldData parentChildIndexFieldData = context.fieldData()
+                        .getForField(parentFieldMapper.fieldType());
+                config.fieldContext(new FieldContext(parentFieldMapper.fieldType().name(), parentChildIndexFieldData,
+                        parentFieldMapper.fieldType()));
+            } else {
+                config.unmapped(true);
+            }
+        } else {
+            config.unmapped(true);
+        }
+        return config;
+    }
+
+    @Override
+    protected XContentBuilder doXContentBody(XContentBuilder builder, Params params) throws IOException {
+        builder.field(ParentToChildrenAggregator.TYPE_FIELD.getPreferredName(), childType);
+        return builder;
+    }
+
+    public static ChildrenAggregationBuilder parse(String aggregationName, QueryParseContext context) throws IOException {
+        String childType = null;
+
+        XContentParser.Token token;
+        String currentFieldName = null;
+        XContentParser parser = context.parser();
+        while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
+            if (token == XContentParser.Token.FIELD_NAME) {
+                currentFieldName = parser.currentName();
+            } else if (token == XContentParser.Token.VALUE_STRING) {
+                if ("type".equals(currentFieldName)) {
+                    childType = parser.text();
+                } else {
+                    throw new ParsingException(parser.getTokenLocation(),
+                            "Unknown key for a " + token + " in [" + aggregationName + "]: [" + currentFieldName + "].");
+                }
+            } else {
+                throw new ParsingException(parser.getTokenLocation(), "Unexpected token " + token + " in [" + aggregationName + "].");
+            }
+        }
+
+        if (childType == null) {
+            throw new ParsingException(parser.getTokenLocation(),
+                    "Missing [child_type] field for children aggregation [" + aggregationName + "]");
+        }
+
+
+        return new ChildrenAggregationBuilder(aggregationName, childType);
+    }
+
+    @Override
+    protected int innerHashCode() {
+        return Objects.hash(childType);
+    }
+
+    @Override
+    protected boolean innerEquals(Object obj) {
+        ChildrenAggregationBuilder other = (ChildrenAggregationBuilder) obj;
+        return Objects.equals(childType, other.childType);
+    }
+
+    @Override
+    public String getType() {
+        return NAME;
+    }
+}