Use FieldNamingStrategy for property name matching.

src/main/asciidoc/reference/elasticsearch-object-mapping.adoc

@@ -71,6 +71,13 @@ This is due to a https://www.elastic.co/guide/en/elasticsearch/reference/current
 
 The mapping metadata infrastructure is defined in a separate spring-data-commons project that is technology agnostic.
 
+==== Mapped field names
+
+Without further configuration, Spring Data Elasticsearch will use the property name of an object as field name in Elasticsearch. This can be changed for individual field by using the `@Field` annotation on that property.
+
+It is also possible to define a `FieldNamingStrategy` in the configuration of the client (<<elasticsearch.clients>>). If for example a `SnakeCaseFieldNamingStrategy` is configured, the property _sampleProperty_ of the object would be mapped to _sample_property_ in Elasticsearch. A `FieldNamingStrategy` applies to all entities; it can be overwritten by
+setting a specific name with `@Field` on a property.
+
 [[elasticsearch.mapping.meta-model.rules]]
 === Mapping Rules
 

src/main/java/org/springframework/data/elasticsearch/config/ElasticsearchConfigurationSupport.java

@@ -33,6 +33,8 @@
 import org.springframework.data.elasticsearch.core.convert.ElasticsearchCustomConversions;
 import org.springframework.data.elasticsearch.core.convert.MappingElasticsearchConverter;
 import org.springframework.data.elasticsearch.core.mapping.SimpleElasticsearchMappingContext;
+import org.springframework.data.mapping.model.FieldNamingStrategy;
+import org.springframework.data.mapping.model.PropertyNameFieldNamingStrategy;
 import org.springframework.lang.Nullable;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.StringUtils;
@@ -69,6 +71,7 @@ public SimpleElasticsearchMappingContext elasticsearchMappingContext(
 		SimpleElasticsearchMappingContext mappingContext = new SimpleElasticsearchMappingContext();
 		mappingContext.setInitialEntitySet(getInitialEntitySet());
 		mappingContext.setSimpleTypeHolder(elasticsearchCustomConversions.getSimpleTypeHolder());
+		mappingContext.setFieldNamingStrategy(fieldNamingStrategy());
 
 		return mappingContext;
 	}
@@ -160,4 +163,14 @@ protected Set<Class<?>> scanForEntities(String basePackage) {
 	protected RefreshPolicy refreshPolicy() {
 		return null;
 	}
+
+	/**
+	 * Configures a {@link FieldNamingStrategy} on the {@link SimpleElasticsearchMappingContext} instance created.
+	 *
+	 * @return the {@link FieldNamingStrategy} to use
+	 * @since 4.2
+	 */
+	protected FieldNamingStrategy fieldNamingStrategy() {
+		return PropertyNameFieldNamingStrategy.INSTANCE;
+	}
 }

src/main/java/org/springframework/data/elasticsearch/core/mapping/SimpleElasticsearchMappingContext.java

@@ -16,9 +16,12 @@
 package org.springframework.data.elasticsearch.core.mapping;
 
 import org.springframework.data.mapping.context.AbstractMappingContext;
+import org.springframework.data.mapping.model.FieldNamingStrategy;
 import org.springframework.data.mapping.model.Property;
+import org.springframework.data.mapping.model.PropertyNameFieldNamingStrategy;
 import org.springframework.data.mapping.model.SimpleTypeHolder;
 import org.springframework.data.util.TypeInformation;
+import org.springframework.lang.Nullable;
 
 /**
  * SimpleElasticsearchMappingContext
@@ -31,6 +34,22 @@
 public class SimpleElasticsearchMappingContext
 		extends AbstractMappingContext<SimpleElasticsearchPersistentEntity<?>, ElasticsearchPersistentProperty> {
 
+	private static final FieldNamingStrategy DEFAULT_NAMING_STRATEGY = PropertyNameFieldNamingStrategy.INSTANCE;
+
+	private FieldNamingStrategy fieldNamingStrategy = DEFAULT_NAMING_STRATEGY;
+
+	/**
+	 * Configures the {@link FieldNamingStrategy} to be used to determine the field name if no manual mapping is applied.
+	 * Defaults to a strategy using the plain property name.
+	 *
+	 * @param fieldNamingStrategy the {@link FieldNamingStrategy} to be used to determine the field name if no manual
+	 *          mapping is applied.
+	 * @since 4.2
+	 */
+	public void setFieldNamingStrategy(@Nullable FieldNamingStrategy fieldNamingStrategy) {
+		this.fieldNamingStrategy = fieldNamingStrategy == null ? DEFAULT_NAMING_STRATEGY : fieldNamingStrategy;
+	}
+
 	@Override
 	protected <T> SimpleElasticsearchPersistentEntity<?> createPersistentEntity(TypeInformation<T> typeInformation) {
 		return new SimpleElasticsearchPersistentEntity<>(typeInformation);
@@ -39,6 +58,6 @@ protected <T> SimpleElasticsearchPersistentEntity<?> createPersistentEntity(Type
 	@Override
 	protected ElasticsearchPersistentProperty createPersistentProperty(Property property,
 			SimpleElasticsearchPersistentEntity<?> owner, SimpleTypeHolder simpleTypeHolder) {
-		return new SimpleElasticsearchPersistentProperty(property, owner, simpleTypeHolder);
+		return new SimpleElasticsearchPersistentProperty(property, owner, simpleTypeHolder, fieldNamingStrategy);
 	}
 }

src/main/java/org/springframework/data/elasticsearch/core/mapping/SimpleElasticsearchPersistentProperty.java

@@ -42,7 +42,9 @@
 import org.springframework.data.mapping.MappingException;
 import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.model.AnnotationBasedPersistentProperty;
+import org.springframework.data.mapping.model.FieldNamingStrategy;
 import org.springframework.data.mapping.model.Property;
+import org.springframework.data.mapping.model.PropertyNameFieldNamingStrategy;
 import org.springframework.data.mapping.model.SimpleTypeHolder;
 import org.springframework.lang.Nullable;
 import org.springframework.util.StringUtils;
@@ -72,13 +74,17 @@ public class SimpleElasticsearchPersistentProperty extends
 	private final @Nullable String annotatedFieldName;
 	@Nullable private ElasticsearchPersistentPropertyConverter propertyConverter;
 	private final boolean storeNullValue;
+	private final FieldNamingStrategy fieldNamingStrategy;
 
 	public SimpleElasticsearchPersistentProperty(Property property,
-			PersistentEntity<?, ElasticsearchPersistentProperty> owner, SimpleTypeHolder simpleTypeHolder) {
+			PersistentEntity<?, ElasticsearchPersistentProperty> owner, SimpleTypeHolder simpleTypeHolder,
+			@Nullable FieldNamingStrategy fieldNamingStrategy) {
 
 		super(property, owner, simpleTypeHolder);
 
 		this.annotatedFieldName = getAnnotatedFieldName();
+		this.fieldNamingStrategy = fieldNamingStrategy == null ? PropertyNameFieldNamingStrategy.INSTANCE
+				: fieldNamingStrategy;
 		this.isId = super.isIdProperty() || SUPPORTED_ID_PROPERTY_NAMES.contains(getFieldName());
 
 		// deprecated since 4.1
@@ -233,7 +239,19 @@ private String getAnnotatedFieldName() {
 
 	@Override
 	public String getFieldName() {
-		return annotatedFieldName == null ? getProperty().getName() : annotatedFieldName;
+
+		if (annotatedFieldName == null) {
+			String fieldName = fieldNamingStrategy.getFieldName(this);
+
+			if (!StringUtils.hasText(fieldName)) {
+				throw new MappingException(String.format("Invalid (null or empty) field name returned for property %s by %s!",
+						this, fieldNamingStrategy.getClass()));
+			}
+
+			return fieldName;
+		}
+
+		return annotatedFieldName;
 	}
 
 	@Override

src/test/java/org/springframework/data/elasticsearch/core/geo/GeoPointUnitTests.java

@@ -7,7 +7,7 @@
 import org.springframework.data.geo.Point;
 
 /**
- * @author P.J. Meisch ([email protected])
+ * @author Peter-Josef Meisch
  */
 class GeoPointUnitTests {
 
@@ -36,7 +36,7 @@ void shouldConvertToAPoint() {
 	@DisplayName("should not be equal to a Point")
 	void shouldNotBeEqualToAPoint() {
 
-		//noinspection AssertBetweenInconvertibleTypes
+		// noinspection AssertBetweenInconvertibleTypes
 		assertThat(new GeoPoint(48, 8)).isNotEqualTo(new Point(8, 48));
 	}
 

src/test/java/org/springframework/data/elasticsearch/core/mapping/FieldNamingStrategyIntegrationReactiveTest.java

@@ -0,0 +1,94 @@
+/*
+ * Copyright 2021 the original author or authors.
+ *
+ * Licensed 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
+ *
+ *      https://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.springframework.data.elasticsearch.core.mapping;
+
+import static org.assertj.core.api.Assertions.*;
+import static org.elasticsearch.index.query.QueryBuilders.*;
+
+import lombok.Builder;
+import lombok.Data;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.annotation.Id;
+import org.springframework.data.elasticsearch.annotations.Document;
+import org.springframework.data.elasticsearch.annotations.Field;
+import org.springframework.data.elasticsearch.annotations.FieldType;
+import org.springframework.data.elasticsearch.core.ReactiveElasticsearchOperations;
+import org.springframework.data.elasticsearch.core.ReactiveIndexOperations;
+import org.springframework.data.elasticsearch.core.SearchHits;
+import org.springframework.data.elasticsearch.core.query.NativeSearchQueryBuilder;
+import org.springframework.data.elasticsearch.core.query.Query;
+import org.springframework.data.elasticsearch.junit.jupiter.ReactiveElasticsearchRestTemplateConfiguration;
+import org.springframework.data.elasticsearch.junit.jupiter.SpringIntegrationTest;
+import org.springframework.data.mapping.model.FieldNamingStrategy;
+import org.springframework.data.mapping.model.SnakeCaseFieldNamingStrategy;
+import org.springframework.test.context.ContextConfiguration;
+import reactor.test.StepVerifier;
+
+/**
+ * @author Peter-Josef Meisch
+ */
+@SpringIntegrationTest
+@ContextConfiguration(classes = { FieldNamingStrategyIntegrationReactiveTest.Config.class })
+public class FieldNamingStrategyIntegrationReactiveTest {
+
+	@Autowired private ReactiveElasticsearchOperations operations;
+
+	@Configuration
+	static class Config extends ReactiveElasticsearchRestTemplateConfiguration {
+
+		@Override
+		protected FieldNamingStrategy fieldNamingStrategy() {
+			return new SnakeCaseFieldNamingStrategy();
+		}
+	}
+
+	@BeforeEach
+	void setUp() {
+		ReactiveIndexOperations indexOps = this.operations.indexOps(Entity.class);
+		indexOps.delete() //
+				.then(indexOps.create()) //
+				.then(indexOps.putMapping()) //
+				.block();
+	}
+
+	@Test // #1565
+	@DisplayName("should use configured FieldNameStrategy")
+	void shouldUseConfiguredFieldNameStrategy() {
+
+		Entity entity = new Entity.EntityBuilder().id("42").someText("the text to be searched").build();
+		operations.save(entity).block();
+
+		// use a native query here to prevent automatic property name matching
+		Query query = new NativeSearchQueryBuilder().withQuery(matchQuery("some_text", "searched")).build();
+		operations.search(query, Entity.class) //
+				.as(StepVerifier::create) //
+				.expectNextCount(1) //
+				.verifyComplete();
+	}
+
+	@Data
+	@Builder
+	@Document(indexName = "field-naming-strategy-test")
+	static class Entity {
+		@Id private String id;
+		@Field(type = FieldType.Text) private String someText;
+	}
+}

src/test/java/org/springframework/data/elasticsearch/core/mapping/FieldNamingStrategyIntegrationTemplateTest.java

@@ -0,0 +1,27 @@
+/*
+ * (c) Copyright 2021 sothawo
+ */
+package org.springframework.data.elasticsearch.core.mapping;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.elasticsearch.junit.jupiter.ElasticsearchTemplateConfiguration;
+import org.springframework.data.mapping.model.FieldNamingStrategy;
+import org.springframework.data.mapping.model.SnakeCaseFieldNamingStrategy;
+import org.springframework.test.context.ContextConfiguration;
+
+/**
+ * @author P.J. Meisch ([email protected])
+ */
+@ContextConfiguration(classes = { FieldNamingStrategyIntegrationTemplateTest.Config.class })
+public class FieldNamingStrategyIntegrationTemplateTest extends FieldNamingStrategyIntegrationTest {
+
+	@Configuration
+	static class Config extends ElasticsearchTemplateConfiguration {
+
+		@Override
+		protected FieldNamingStrategy fieldNamingStrategy() {
+			return new SnakeCaseFieldNamingStrategy();
+		}
+	}
+
+}

src/test/java/org/springframework/data/elasticsearch/core/mapping/FieldNamingStrategyIntegrationTest.java

@@ -0,0 +1,101 @@
+/*
+ * Copyright 2021 the original author or authors.
+ *
+ * Licensed 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
+ *
+ *      https://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.springframework.data.elasticsearch.core.mapping;
+
+import static org.assertj.core.api.Assertions.*;
+import static org.elasticsearch.index.query.QueryBuilders.*;
+
+import lombok.Builder;
+import lombok.Data;
+
+import org.elasticsearch.client.RestHighLevelClient;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.annotation.Id;
+import org.springframework.data.elasticsearch.annotations.Document;
+import org.springframework.data.elasticsearch.annotations.Field;
+import org.springframework.data.elasticsearch.annotations.FieldType;
+import org.springframework.data.elasticsearch.core.ElasticsearchOperations;
+import org.springframework.data.elasticsearch.core.IndexOperations;
+import org.springframework.data.elasticsearch.core.SearchHits;
+import org.springframework.data.elasticsearch.core.convert.ElasticsearchConverter;
+import org.springframework.data.elasticsearch.core.query.NativeSearchQueryBuilder;
+import org.springframework.data.elasticsearch.core.query.Query;
+import org.springframework.data.elasticsearch.junit.jupiter.ElasticsearchRestTemplateConfiguration;
+import org.springframework.data.elasticsearch.junit.jupiter.SpringIntegrationTest;
+import org.springframework.data.mapping.model.FieldNamingStrategy;
+import org.springframework.data.mapping.model.SnakeCaseFieldNamingStrategy;
+import org.springframework.test.context.ContextConfiguration;
+
+/**
+ * @author Peter-Josef Meisch
+ */
+@SpringIntegrationTest
+@ContextConfiguration(classes = { FieldNamingStrategyIntegrationTest.Config.class })
+public class FieldNamingStrategyIntegrationTest {
+
+	@Autowired private ElasticsearchOperations operations;
+
+	@Configuration
+	static class Config extends ElasticsearchRestTemplateConfiguration {
+
+		@Override
+		@Bean
+		public ElasticsearchOperations elasticsearchOperations(ElasticsearchConverter elasticsearchConverter,
+				RestHighLevelClient elasticsearchClient) {
+			return super.elasticsearchOperations(elasticsearchConverter, elasticsearchClient);
+		}
+
+		@Override
+		protected FieldNamingStrategy fieldNamingStrategy() {
+			return new SnakeCaseFieldNamingStrategy();
+		}
+	}
+
+	@BeforeEach
+	void setUp() {
+		IndexOperations indexOps = this.operations.indexOps(Entity.class);
+		indexOps.delete();
+		indexOps.create();
+		indexOps.putMapping();
+	}
+
+	@Test // #1565
+	@DisplayName("should use configured FieldNameStrategy")
+	void shouldUseConfiguredFieldNameStrategy() {
+
+		Entity entity = new Entity.EntityBuilder().id("42").someText("the text to be searched").build();
+		operations.save(entity);
+
+		// use a native query here to prevent automatic property name matching
+		Query query = new NativeSearchQueryBuilder().withQuery(matchQuery("some_text", "searched")).build();
+		SearchHits<Entity> searchHits = operations.search(query, Entity.class);
+
+		assertThat(searchHits.getTotalHits()).isEqualTo(1);
+	}
+
+	@Data
+	@Builder
+	@Document(indexName = "field-naming-strategy-test")
+	static class Entity {
+		@Id private String id;
+		@Field(type = FieldType.Text) private String someText;
+	}
+}

src/test/java/org/springframework/data/elasticsearch/core/mapping/SimpleElasticsearchPersistentEntityTests.java

@@ -152,7 +152,7 @@ private static SimpleElasticsearchPersistentProperty createProperty(SimpleElasti
 
 		TypeInformation<?> type = entity.getTypeInformation();
 		Property property = Property.of(type, ReflectionUtils.findField(entity.getType(), field));
-		return new SimpleElasticsearchPersistentProperty(property, entity, SimpleTypeHolder.DEFAULT);
+		return new SimpleElasticsearchPersistentProperty(property, entity, SimpleTypeHolder.DEFAULT, null);
 
 	}