Add support for stored fields.

Original Pull Request #2005 
Closes #2004

Author: vdiskg

Diff for: src/main/java/org/springframework/data/elasticsearch/backend/elasticsearch7/RequestFactory.java

@@ -116,6 +116,7 @@
  * @author Subhobrata Dey
  * @author Farid Faoudi
  * @author Peer Mueller
+ * @author vdisk
  * @since 4.0
  */
 // todo make package private again after refactoring
@@ -670,6 +671,10 @@ private SearchRequest prepareSearchRequest(Query query, @Nullable Class<?> clazz
 			query.getFields().forEach(sourceBuilder::fetchField);
 		}
 
+		if (!isEmpty(query.getStoredFields())) {
+			sourceBuilder.storedFields(query.getStoredFields());
+		}
+
 		if (query.getIndicesOptions() != null) {
 			request.indicesOptions(toElasticsearchIndicesOptions(query.getIndicesOptions()));
 		}

Diff for: src/main/java/org/springframework/data/elasticsearch/backend/elasticsearch7/query/NativeSearchQueryBuilder.java

@@ -54,6 +54,7 @@
  * @author Farid Azaza
  * @author Peter-Josef Meisch
  * @author Peer Mueller
+ * @author vdisk
  */
 public class NativeSearchQueryBuilder {
 
@@ -67,6 +68,7 @@ public class NativeSearchQueryBuilder {
 	@Nullable private List<HighlightBuilder.Field> highlightFields = new ArrayList<>();
 	private Pageable pageable = Pageable.unpaged();
 	@Nullable private List<String> fields = new ArrayList<>();
+	@Nullable protected List<String> storedFields;
 	@Nullable private SourceFilter sourceFilter;
 	@Nullable private CollapseBuilder collapseBuilder;
 	@Nullable private List<IndexBoost> indicesBoost = new ArrayList<>();
@@ -242,6 +244,23 @@ public NativeSearchQueryBuilder withFields(String... fields) {
 		return this;
 	}
 
+	public NativeSearchQueryBuilder withStoredFields(Collection<String> storedFields) {
+		if (this.storedFields == null) {
+			this.storedFields = new ArrayList<>(storedFields);
+		} else {
+			this.storedFields.addAll(storedFields);
+		}
+		return this;
+	}
+
+	public NativeSearchQueryBuilder withStoredFields(String... storedFields) {
+		if (this.storedFields == null) {
+			this.storedFields = new ArrayList<>(storedFields.length);
+		}
+		Collections.addAll(this.storedFields, storedFields);
+		return this;
+	}
+
 	public NativeSearchQueryBuilder withSourceFilter(SourceFilter sourceFilter) {
 		this.sourceFilter = sourceFilter;
 		return this;
@@ -342,6 +361,10 @@ public NativeSearchQuery build() {
 			nativeSearchQuery.setFields(fields);
 		}
 
+		if (storedFields != null) {
+			nativeSearchQuery.setStoredFields(storedFields);
+		}
+
 		if (sourceFilter != null) {
 			nativeSearchQuery.addSourceFilter(sourceFilter);
 		}

Diff for: src/main/java/org/springframework/data/elasticsearch/core/convert/MappingElasticsearchConverter.java

@@ -84,6 +84,7 @@
  * @author Subhobrata Dey
  * @author Marc Vanbrabant
  * @author Anton Naydenov
+ * @author vdisk
  * @since 3.2
  */
 public class MappingElasticsearchConverter
@@ -1148,6 +1149,11 @@ private void updateFieldsAndSourceFilter(Query query, Class<?> domainClass) {
 				query.setFields(updateFieldNames(fields, persistentEntity));
 			}
 
+			List<String> storedFields = query.getStoredFields();
+			if (!CollectionUtils.isEmpty(storedFields)) {
+				query.setStoredFields(updateFieldNames(storedFields, persistentEntity));
+			}
+
 			SourceFilter sourceFilter = query.getSourceFilter();
 
 			if (sourceFilter != null) {

Diff for: src/main/java/org/springframework/data/elasticsearch/core/query/BaseQuery.java

@@ -43,12 +43,14 @@
  * @author Farid Azaza
  * @author Peter-Josef Meisch
  * @author Peer Mueller
+ * @author vdisk
  */
 public class BaseQuery implements Query {
 
 	protected Pageable pageable = DEFAULT_PAGE;
 	@Nullable protected Sort sort;
 	protected List<String> fields = new ArrayList<>();
+	@Nullable protected List<String> storedFields;
 	@Nullable protected SourceFilter sourceFilter;
 	protected float minScore;
 	@Nullable protected Collection<String> ids;
@@ -109,6 +111,28 @@ public void setFields(List<String> fields) {
 		this.fields.addAll(fields);
 	}
 
+	@Override
+	public void addStoredFields(String... storedFields) {
+		if (storedFields.length == 0) {
+			return;
+		}
+		if (this.storedFields == null) {
+			this.storedFields = new ArrayList<>(storedFields.length);
+		}
+		addAll(this.storedFields, storedFields);
+	}
+
+	@Nullable
+	@Override
+	public List<String> getStoredFields() {
+		return storedFields;
+	}
+
+	@Override
+	public void setStoredFields(@Nullable List<String> storedFields) {
+		this.storedFields = storedFields;
+	}
+
 	@Override
 	public void addSourceFilter(SourceFilter sourceFilter) {
 		this.sourceFilter = sourceFilter;

Diff for: src/main/java/org/springframework/data/elasticsearch/core/query/Query.java

@@ -41,6 +41,7 @@
  * @author Farid Azaza
  * @author Peter-Josef Meisch
  * @author Peer Mueller
+ * @author vdisk
  */
 public interface Query {
 
@@ -108,6 +109,28 @@ static Query findAll() {
 	 */
 	void setFields(List<String> fields);
 
+	/**
+	 * Add stored fields to be added as part of search request
+	 *
+	 * @param storedFields
+	 */
+	void addStoredFields(String... storedFields);
+
+	/**
+	 * Get stored fields to be returned as part of search request
+	 *
+	 * @return null if not set
+	 */
+	@Nullable
+	List<String> getStoredFields();
+
+	/**
+	 * Set stored fields to be returned as part of search request
+	 *
+	 * @param storedFields
+	 */
+	void setStoredFields(@Nullable List<String> storedFields);
+
 	/**
 	 * Add source filter to be added as part of search request
 	 *

Diff for: src/test/java/org/springframework/data/elasticsearch/backend/elasticsearch7/CriteriaQueryMappingUnitTests.java

@@ -56,6 +56,7 @@
  *
  * @author Peter-Josef Meisch
  * @author Sascha Woo
+ * @author vdisk
  */
 public class CriteriaQueryMappingUnitTests {
 
@@ -443,6 +444,22 @@ void shouldMapNamesInSourceFieldsAndSourceFilters() {
 		softly.assertAll();
 	}
 
+	@Test
+	@DisplayName("should map names in source stored fields")
+	void shouldMapNamesInSourceStoredFields() {
+
+		Query query = Query.findAll();
+		query.addStoredFields("firstName", "lastName");
+
+		mappingElasticsearchConverter.updateQuery(query, Person.class);
+
+		SoftAssertions softly = new SoftAssertions();
+		List<String> storedFields = query.getStoredFields();
+		softly.assertThat(storedFields).isNotNull();
+		softly.assertThat(storedFields).containsExactly("first-name", "last-name");
+		softly.assertAll();
+	}
+
 	// endregion
 
 	// region helper functions

Diff for: src/test/java/org/springframework/data/elasticsearch/backend/elasticsearch7/RequestFactoryTests.java

@@ -73,6 +73,7 @@
  * @author Peter-Josef Meisch
  * @author Roman Puchkovskiy
  * @author Peer Mueller
+ * @author vdisk
  */
 @SuppressWarnings("ConstantConditions")
 @ExtendWith(MockitoExtension.class)
@@ -547,6 +548,18 @@ void shouldSetRequestCacheFalseOnSearchRequest() {
 		assertThat(searchRequest.requestCache()).isFalse();
 	}
 
+	@Test
+	@DisplayName("should set stored fields on SearchRequest")
+	void shouldSetStoredFieldsOnSearchRequest() {
+
+		Query query = new NativeSearchQueryBuilder().withQuery(matchAllQuery()).withStoredFields("lastName", "location").build();
+
+		SearchRequest searchRequest = requestFactory.searchRequest(query, Person.class, IndexCoordinates.of("persons"));
+
+		assertThat(searchRequest.source().storedFields()).isNotNull();
+		assertThat(searchRequest.source().storedFields().fieldNames()).isEqualTo(Arrays.asList("last-name", "current-location"));
+	}
+
 	// region entities
 	static class Person {
 		@Nullable @Id String id;