Add runtime fields to index mapping.

Original Pull Request: #1820 
Closes: #1816

Author: sothawo

Diff for: src/main/asciidoc/reference/elasticsearch-misc.adoc

@@ -51,10 +51,24 @@ class Entity {
 
 When Spring Data Elasticsearch creates the index mapping with the `IndexOperations.createMapping()` methods, it uses the annotations described in <<elasticsearch.mapping.meta-model.annotations>>, especially the `@Field` annotation. In addition to that it is possible to add the `@Mapping` annotation to a class. This annotation has the following properties:
 
-* `mappingPath` a classpath resource in JSON format which is used as the mapping, no other mapping processing is done.
+* `mappingPath` a classpath resource in JSON format; if this is not empty it is used as the mapping, no other mapping processing is done.
 * `enabled`  when set to false, this flag is written to the mapping and no further processing is done.
 * `dateDetection` and `numericDetection` set the corresponding properties in the mapping when not set to `DEFAULT`.
 * `dynamicDateFormats` when this String array is not empty, it defines the date formats used for automatic date detection.
+* `runtimeFieldsPath` a classpath resource in JSON format containing the definition of runtime fields which is written to the index mappings, for example:
+====
+[source,json]
+----
+{
+  "day_of_week": {
+    "type": "keyword",
+    "script": {
+      "source": "emit(doc['@timestamp'].value.dayOfWeekEnum.getDisplayName(TextStyle.FULL, Locale.ROOT))"
+    }
+  }
+}
+----
+====
 
 [[elasticsearch.misc.filter]]
 == Filter Builder

Diff for: src/main/java/org/springframework/data/elasticsearch/annotations/Mapping.java

@@ -27,6 +27,7 @@
  * Elasticsearch Mapping
  *
  * @author Mohsin Husen
+ * @author Peter-Josef Meisch
  */
 @Persistent
 @Inherited
@@ -42,6 +43,7 @@
 	 * @since 4.2
 	 */
 	boolean enabled() default true;
+
 	/**
 	 * whether date_detection is enabled
 	 *
@@ -58,10 +60,20 @@
 
 	/**
 	 * custom dynamic date formats
+	 *
 	 * @since 4.3
 	 */
 	String[] dynamicDateFormats() default {};
 
+	/**
+	 * classpath to a JSON file containing the values for a runtime mapping definition. The file must contain the JSON
+	 * object that is written as the value of the runtime property. {@see <a href=
+	 * "https://www.elastic.co/guide/en/elasticsearch/reference/7.12/runtime-mapping-fields.html">elasticsearch doc</a>}
+	 *
+	 * @since 4.3
+	 */
+	String runtimeFieldsPath() default "";
+
 	enum Detection {
 		DEFAULT, TRUE, FALSE;
 	}

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

@@ -219,8 +219,6 @@ protected Document buildMapping(Class<?> clazz) {
 				if (hasText(mappings)) {
 					return Document.parse(mappings);
 				}
-			} else {
-				LOGGER.info("mappingPath in @Mapping has to be defined. Building mappings using @Field");
 			}
 		}
 

Diff for: src/main/java/org/springframework/data/elasticsearch/core/index/MappingBuilder.java

@@ -95,6 +95,7 @@ public class MappingBuilder {
 	private static final String DATE_DETECTION = "date_detection";
 	private static final String NUMERIC_DETECTION = "numeric_detection";
 	private static final String DYNAMIC_DATE_FORMATS = "dynamic_date_formats";
+	private static final String RUNTIME = "runtime";
 
 	private final ElasticsearchConverter elasticsearchConverter;
 
@@ -168,6 +169,10 @@ private void mapEntity(XContentBuilder builder, @Nullable ElasticsearchPersisten
 			if (mappingAnnotation.dynamicDateFormats().length > 0) {
 				builder.field(DYNAMIC_DATE_FORMATS, mappingAnnotation.dynamicDateFormats());
 			}
+
+			if (StringUtils.hasText(mappingAnnotation.runtimeFieldsPath())) {
+				addRuntimeFields(builder, mappingAnnotation.runtimeFieldsPath());
+			}
 		}
 
 		boolean writeNestedProperties = !isRootObject && (isAnyPropertyAnnotatedWithField(entity) || nestedOrObjectField);
@@ -222,6 +227,15 @@ private void mapEntity(XContentBuilder builder, @Nullable ElasticsearchPersisten
 
 	}
 
+	private void addRuntimeFields(XContentBuilder builder, String runtimeFieldsPath) throws IOException {
+
+		ClassPathResource runtimeFields = new ClassPathResource(runtimeFieldsPath);
+
+		if (runtimeFields.exists()) {
+			builder.rawField(RUNTIME, runtimeFields.getInputStream(), XContentType.JSON);
+		}
+	}
+
 	private void buildPropertyMapping(XContentBuilder builder, boolean isRootObject,
 			ElasticsearchPersistentProperty property) throws IOException {
 

Diff for: src/test/java/org/springframework/data/elasticsearch/core/index/MappingBuilderIntegrationTests.java

@@ -25,6 +25,7 @@
 import java.lang.Integer;
 import java.lang.Object;
 import java.math.BigDecimal;
+import java.time.Instant;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Date;
@@ -316,6 +317,16 @@ void shouldWriteDynamicDetectionValues() {
 		indexOps.delete();
 	}
 
+	@Test // #1816
+	@DisplayName("should write runtime fields")
+	void shouldWriteRuntimeFields() {
+
+		IndexOperations indexOps = operations.indexOps(RuntimeFieldEntity.class);
+		indexOps.create();
+		indexOps.putMapping();
+		indexOps.delete();
+	}
+
 	// region entities
 	@Document(indexName = "ignore-above-index")
 	static class IgnoreAboveEntity {
@@ -1130,6 +1141,14 @@ public void setAuthor(Author author) {
 	private static class DynamicDetectionMapping {
 		@Id @Nullable private String id;
 	}
+
+	@Document(indexName = "runtime-fields")
+	@Mapping(runtimeFieldsPath = "/mappings/runtime-fields.json")
+	private static class RuntimeFieldEntity {
+		@Id @Nullable private String id;
+		@Field(type = Date, format = DateFormat.epoch_millis, name = "@timestamp") @Nullable private Instant timestamp;
+	}
+
 	// endregion
 
 }

Diff for: src/test/java/org/springframework/data/elasticsearch/core/index/MappingBuilderUnitTests.java

@@ -26,6 +26,7 @@
 import java.lang.Integer;
 import java.lang.Object;
 import java.math.BigDecimal;
+import java.time.Instant;
 import java.time.LocalDate;
 import java.time.LocalDateTime;
 import java.util.Collection;
@@ -855,7 +856,38 @@ void shouldWriteDynamicDateFormats() throws JSONException {
 		assertEquals(expected, mapping, true);
 	}
 
+	@Test // #1816
+	@DisplayName("should write runtime fields")
+	void shouldWriteRuntimeFields() throws JSONException {
+
+		String expected = "{\n" + //
+				"  \"runtime\": {\n" + //
+				"    \"day_of_week\": {\n" + //
+				"      \"type\": \"keyword\",\n" + //
+				"      \"script\": {\n" + //
+				"        \"source\": \"emit(doc['@timestamp'].value.dayOfWeekEnum.getDisplayName(TextStyle.FULL, Locale.ROOT))\"\n" + //
+				"      }\n" + //
+				"    }\n" + //
+				"  },\n" + //
+				"  \"properties\": {\n" + //
+				"    \"_class\": {\n" + //
+				"      \"type\": \"keyword\",\n" + //
+				"      \"index\": false,\n" + //
+				"      \"doc_values\": false\n" + //
+				"    },\n" + //
+				"    \"@timestamp\": {\n" + //
+				"      \"type\": \"date\",\n" + //
+				"      \"format\": \"epoch_millis\"\n" + //
+				"    }\n" + //
+				"  }\n" + //
+				"}\n"; //
+
+		String mapping = getMappingBuilder().buildPropertyMapping(RuntimeFieldEntity.class);
+
+		assertEquals(expected, mapping, true);
+	}
 	// region entities
+
 	@Document(indexName = "ignore-above-index")
 	static class IgnoreAboveEntity {
 		@Nullable @Id private String id;
@@ -1778,7 +1810,7 @@ private static class DynamicDetectionMappingDefault {
 	}
 
 	@Document(indexName = "dynamic-dateformats-mapping")
-	@Mapping(dynamicDateFormats = {"date1", "date2"})
+	@Mapping(dynamicDateFormats = { "date1", "date2" })
 	private static class DynamicDateFormatsMapping {
 		@Id @Nullable private String id;
 	}
@@ -1794,5 +1826,12 @@ private static class DynamicDetectionMappingTrue {
 	private static class DynamicDetectionMappingFalse {
 		@Id @Nullable private String id;
 	}
+
+	@Document(indexName = "runtime-fields")
+	@Mapping(runtimeFieldsPath = "/mappings/runtime-fields.json")
+	private static class RuntimeFieldEntity {
+		@Id @Nullable private String id;
+		@Field(type = Date, format = DateFormat.epoch_millis, name = "@timestamp") @Nullable private Instant timestamp;
+	}
 	// endregion
 }

Diff for: src/test/resources/mappings/runtime-fields.json

@@ -0,0 +1,8 @@
+{
+  "day_of_week": {
+    "type": "keyword",
+    "script": {
+      "source": "emit(doc['@timestamp'].value.dayOfWeekEnum.getDisplayName(TextStyle.FULL, Locale.ROOT))"
+    }
+  }
+}