DATAES-848 - Add the name of the index to SearchHit.

Original PR: spring-projects#471

Author: sothawo

src/main/java/org/springframework/data/elasticsearch/core/SearchHit.java

@@ -35,14 +35,16 @@
  */
 public class SearchHit<T> {
 
-	private final String id;
+	@Nullable private final String index;
+	@Nullable private final String id;
 	private final float score;
 	private final List<Object> sortValues;
 	private final T content;
 	private final Map<String, List<String>> highlightFields = new LinkedHashMap<>();
 
-	public SearchHit(@Nullable String id, float score, @Nullable Object[] sortValues,
+	public SearchHit(@Nullable String index, @Nullable String id, float score, @Nullable Object[] sortValues,
 			@Nullable Map<String, List<String>> highlightFields, T content) {
+		this.index = index;
 		this.id = id;
 		this.score = score;
 		this.sortValues = (sortValues != null) ? Arrays.asList(sortValues) : new ArrayList<>();
@@ -53,6 +55,15 @@ public SearchHit(@Nullable String id, float score, @Nullable Object[] sortValues
 		this.content = content;
 	}
 
+	/**
+	 * @return the index name where the hit's document was found
+	 * @since 4.1
+	 */
+	@Nullable
+	public String getIndex() {
+		return index;
+	}
+
 	@Nullable
 	public String getId() {
 		return id;

src/main/java/org/springframework/data/elasticsearch/core/SearchHitMapping.java

@@ -62,12 +62,13 @@ SearchHit<T> mapHit(SearchDocument searchDocument, T content) {
 		Assert.notNull(searchDocument, "searchDocument is null");
 		Assert.notNull(content, "content is null");
 
+		String index = searchDocument.getIndex();
 		String id = searchDocument.hasId() ? searchDocument.getId() : null;
 		float score = searchDocument.getScore();
 		Object[] sortValues = searchDocument.getSortValues();
 		Map<String, List<String>> highlightFields = getHighlightsAndRemapFieldNames(searchDocument);
 
-		return new SearchHit<>(id, score, sortValues, highlightFields, content);
+		return new SearchHit<>(index, id, score, sortValues, highlightFields, content);
 	}
 
 	SearchHits<T> mapHits(SearchDocumentResponse searchDocumentResponse, List<T> contents) {

src/main/java/org/springframework/data/elasticsearch/core/document/Document.java

@@ -111,6 +111,27 @@ default boolean hasId() {
 		return false;
 	}
 
+	/**
+	 * @return the index if this document was retrieved from an index
+	 * @since 4.1
+	 */
+	@Nullable
+	default String getIndex() {
+		return null;
+	}
+
+	/**
+	 * Sets the index name for this document
+	 * 
+	 * @param index index name
+	 *          <p>
+	 *          The default implementation throws {@link UnsupportedOperationException}.
+	 * @since 4.1
+	 */
+	default void setIndex(@Nullable String index) {
+		throw new UnsupportedOperationException();
+	}
+
 	/**
 	 * Retrieve the identifier associated with this {@link Document}.
 	 * <p>
@@ -461,4 +482,5 @@ default <R> R transform(Function<? super Document, ? extends R> transformer) {
 	 * @return a JSON representation of this document.
 	 */
 	String toJson();
+
 }