Merge pull request #39941 from schauder

* pr/39941:
  Polish "Add property spring.data.jdbc.dialect"
  Add property spring.data.jdbc.dialect

Closes gh-39941

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/jdbc/JdbcDataProperties.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2024 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.boot.autoconfigure.data.jdbc;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+
+/**
+ * Configuration properties for Spring Data JDBC.
+ *
+ * @author Jens Schauder
+ * @since 3.3.0
+ */
+@ConfigurationProperties(prefix = "spring.data.jdbc")
+public class JdbcDataProperties {
+
+	/**
+	 * Dialect to use. By default, the dialect is determined by inspecting the database
+	 * connection.
+	 */
+	private JdbcDatabaseDialect dialect;
+
+	public JdbcDatabaseDialect getDialect() {
+		return this.dialect;
+	}
+
+	public void setDialect(JdbcDatabaseDialect dialect) {
+		this.dialect = dialect;
+	}
+
+}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/jdbc/JdbcDatabaseDialect.java

@@ -0,0 +1,120 @@
+/*
+ * Copyright 2012-2024 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.boot.autoconfigure.data.jdbc;
+
+import java.util.function.Supplier;
+
+import org.springframework.data.jdbc.core.dialect.JdbcDb2Dialect;
+import org.springframework.data.jdbc.core.dialect.JdbcMySqlDialect;
+import org.springframework.data.jdbc.core.dialect.JdbcPostgresDialect;
+import org.springframework.data.jdbc.core.dialect.JdbcSqlServerDialect;
+import org.springframework.data.relational.core.dialect.Dialect;
+import org.springframework.data.relational.core.dialect.H2Dialect;
+import org.springframework.data.relational.core.dialect.HsqlDbDialect;
+import org.springframework.data.relational.core.dialect.MariaDbDialect;
+import org.springframework.data.relational.core.dialect.OracleDialect;
+
+/**
+ * List of database dialects that can be configured in Boot for use with Spring Data JDBC.
+ *
+ * @author Jens Schauder
+ * @since 3.3.0
+ */
+public enum JdbcDatabaseDialect implements Supplier<Dialect> {
+
+	/**
+	 * Provides an instance of {@link JdbcDb2Dialect}.
+	 */
+	DB2 {
+		@Override
+		public Dialect get() {
+			return JdbcDb2Dialect.INSTANCE;
+		}
+	},
+
+	/**
+	 * Provides an instance of {@link H2Dialect}.
+	 */
+	H2 {
+		@Override
+		public Dialect get() {
+			return H2Dialect.INSTANCE;
+		}
+	},
+
+	/**
+	 * Provides an instance of {@link HsqlDbDialect}.
+	 */
+	HSQL {
+		@Override
+		public Dialect get() {
+			return HsqlDbDialect.INSTANCE;
+		}
+	},
+
+	/**
+	 * Provides an instance of {@link MariaDbDialect}.
+	 */
+	MARIA {
+		@Override
+		public Dialect get() {
+			return MariaDbDialect.INSTANCE;
+		}
+	},
+
+	/**
+	 * Provides an instance of {@link JdbcMySqlDialect}.
+	 */
+	MYSQL {
+		@Override
+		public Dialect get() {
+			return JdbcMySqlDialect.INSTANCE;
+		}
+	},
+
+	/**
+	 * Provides an instance of {@link OracleDialect}.
+	 */
+	ORACLE {
+		@Override
+		public Dialect get() {
+			return OracleDialect.INSTANCE;
+
+		}
+	},
+
+	/**
+	 * Provides an instance of {@link JdbcPostgresDialect}.
+	 */
+	POSTGRESQL {
+		@Override
+		public Dialect get() {
+			return JdbcPostgresDialect.INSTANCE;
+		}
+	},
+
+	/**
+	 * Provides an instance of {@link JdbcSqlServerDialect}.
+	 */
+	SQL_SERVER {
+		@Override
+		public Dialect get() {
+			return JdbcSqlServerDialect.INSTANCE;
+		}
+	}
+
+}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/jdbc/JdbcRepositoriesAutoConfiguration.java

@@ -28,6 +28,7 @@ import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.autoconfigure.domain.EntityScanner;
 import org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration;
 import org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -59,6 +60,7 @@ import org.springframework.transaction.PlatformTransactionManager;
  * @author Andy Wilkinson
  * @author Stephane Nicoll
  * @author Mark Paluch
+ * @author Jens Schauder
  * @since 2.1.0
  * @see EnableJdbcRepositories
  */
@@ -67,6 +69,7 @@ import org.springframework.transaction.PlatformTransactionManager;
 @ConditionalOnClass({ NamedParameterJdbcOperations.class, AbstractJdbcConfiguration.class })
 @ConditionalOnProperty(prefix = "spring.data.jdbc.repositories", name = "enabled", havingValue = "true",
 		matchIfMissing = true)
+@EnableConfigurationProperties(JdbcDataProperties.class)
 public class JdbcRepositoriesAutoConfiguration {
 
 	@Configuration(proxyBeanMethods = false)
@@ -82,8 +85,11 @@ public class JdbcRepositoriesAutoConfiguration {
 
 		private final ApplicationContext applicationContext;
 
-		SpringBootJdbcConfiguration(ApplicationContext applicationContext) {
+		private final JdbcDataProperties properties;
+
+		SpringBootJdbcConfiguration(ApplicationContext applicationContext, JdbcDataProperties properties) {
 			this.applicationContext = applicationContext;
+			this.properties = properties;
 		}
 
 		@Override
@@ -141,6 +147,10 @@ public class JdbcRepositoriesAutoConfiguration {
 		@Bean
 		@ConditionalOnMissingBean
 		public Dialect jdbcDialect(NamedParameterJdbcOperations operations) {
+			JdbcDatabaseDialect dialect = this.properties.getDialect();
+			if (dialect != null) {
+				return dialect.get();
+			}
 			return super.jdbcDialect(operations);
 		}
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/data/jdbc/JdbcRepositoriesAutoConfigurationTests.java

@@ -40,6 +40,7 @@ import org.springframework.data.jdbc.core.JdbcAggregateTemplate;
 import org.springframework.data.jdbc.core.convert.DataAccessStrategy;
 import org.springframework.data.jdbc.core.convert.JdbcConverter;
 import org.springframework.data.jdbc.core.convert.JdbcCustomConversions;
+import org.springframework.data.jdbc.core.dialect.JdbcPostgresDialect;
 import org.springframework.data.jdbc.core.mapping.JdbcMappingContext;
 import org.springframework.data.jdbc.repository.config.AbstractJdbcConfiguration;
 import org.springframework.data.jdbc.repository.config.EnableJdbcRepositories;
@@ -58,6 +59,7 @@ import static org.mockito.Mockito.mock;
  * @author Andy Wilkinson
  * @author Stephane Nicoll
  * @author Mark Paluch
+ * @author Jens Schauder
  */
 class JdbcRepositoriesAutoConfigurationTests {
 
@@ -181,6 +183,16 @@ class JdbcRepositoriesAutoConfigurationTests {
 		allowsUserToDefineCustomBean(DialectConfiguration.class, Dialect.class, "customDialect");
 	}
 
+	@Test
+	void allowsConfigurationOfDialectByProperty() {
+		this.contextRunner.with(database())
+			.withPropertyValues("spring.data.jdbc.dialect=postgresql")
+			.withConfiguration(AutoConfigurations.of(JdbcTemplateAutoConfiguration.class,
+					DataSourceTransactionManagerAutoConfiguration.class))
+			.withUserConfiguration(TestConfiguration.class)
+			.run((context) -> assertThat(context).hasSingleBean(JdbcPostgresDialect.class));
+	}
+
 	private void allowsUserToDefineCustomBean(Class<?> configuration, Class<?> beanType, String beanName) {
 		this.contextRunner.with(database())
 			.withConfiguration(AutoConfigurations.of(JdbcTemplateAutoConfiguration.class,