Merge branch 'pr/22772'

core/src/main/java/org/elasticsearch/search/fetch/subphase/ParentFieldSubFetchPhase.java

@@ -63,6 +63,10 @@ public final class ParentFieldSubFetchPhase implements FetchSubPhase {
     public static String getParentId(ParentFieldMapper fieldMapper, LeafReader reader, int docId) {
         try {
             SortedDocValues docValues = reader.getSortedDocValues(fieldMapper.name());
+            if (docValues == null) {
+                // hit has no _parent field.
+                return null;
+            }
             BytesRef parentId = docValues.get(docId);
             return parentId.length > 0 ? parentId.utf8ToString() : null;
         } catch (IOException e) {

core/src/test/java/org/elasticsearch/search/fetch/subphase/ParentFieldSubFetchPhaseTests.java

@@ -0,0 +1,82 @@
+/*
+ * 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.fetch.subphase;
+
+import org.apache.lucene.document.Document;
+import org.apache.lucene.document.SortedDocValuesField;
+import org.apache.lucene.index.DirectoryReader;
+import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.index.IndexWriter;
+import org.apache.lucene.store.Directory;
+import org.apache.lucene.util.BytesRef;
+import org.elasticsearch.Version;
+import org.elasticsearch.cluster.metadata.IndexMetaData;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.index.mapper.ContentPath;
+import org.elasticsearch.index.mapper.Mapper;
+import org.elasticsearch.index.mapper.ParentFieldMapper;
+import org.elasticsearch.test.ESTestCase;
+
+public class ParentFieldSubFetchPhaseTests extends ESTestCase {
+
+    public void testGetParentId() throws Exception {
+        ParentFieldMapper fieldMapper = createParentFieldMapper();
+        Directory directory = newDirectory();
+        IndexWriter indexWriter = new IndexWriter(directory, newIndexWriterConfig());
+        Document document = new Document();
+        document.add(new SortedDocValuesField(fieldMapper.fieldType().name(), new BytesRef("1")));
+        indexWriter.addDocument(document);
+        indexWriter.close();
+
+        IndexReader indexReader = DirectoryReader.open(directory);
+        String id = ParentFieldSubFetchPhase.getParentId(fieldMapper, indexReader.leaves().get(0).reader(), 0);
+        assertEquals("1", id);
+
+        indexReader.close();
+        directory.close();
+    }
+
+    public void testGetParentIdNoParentField() throws Exception {
+        ParentFieldMapper fieldMapper = createParentFieldMapper();
+        Directory directory = newDirectory();
+        IndexWriter indexWriter = new IndexWriter(directory, newIndexWriterConfig());
+        Document document = new Document();
+        document.add(new SortedDocValuesField("different_field", new BytesRef("1")));
+        indexWriter.addDocument(document);
+        indexWriter.close();
+
+        IndexReader indexReader = DirectoryReader.open(directory);
+        String id = ParentFieldSubFetchPhase.getParentId(fieldMapper, indexReader.leaves().get(0).reader(), 0);
+        assertNull(id);
+
+        indexReader.close();
+        directory.close();
+    }
+
+    private ParentFieldMapper createParentFieldMapper() {
+        Settings settings = Settings.builder()
+                .put(IndexMetaData.SETTING_VERSION_CREATED, Version.CURRENT)
+                .build();
+        return new ParentFieldMapper.Builder("type")
+                .type("parent_type")
+                .build(new Mapper.BuilderContext(settings, new ContentPath(0)));
+    }
+
+
+}