Merge pull request #7796 from eddumelendez:gh-7708

* pr/7796:
  Polish contribution
  Autodetect spring.jpa.database from spring.datasource.url

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/orm/jpa/DatabasePlatform.java

+/*
+ * Copyright 2012-2016 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
+ *
+ *      http://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.orm.jpa;
+
+import org.springframework.boot.jdbc.DatabaseDriver;
+import org.springframework.orm.jpa.vendor.Database;
+
+/**
+ * Mapper between {@link Database} and {@link DatabaseDriver}.
+ *
+ * @author Eddú Meléndez
+ */
+enum DatabasePlatform {
+
+	DB2(Database.DB2, DatabaseDriver.DB2),
+
+	DERBY(Database.DERBY, DatabaseDriver.DERBY),
+
+	H2(Database.H2, DatabaseDriver.H2),
+
+	HSQL(Database.HSQL, DatabaseDriver.HSQLDB),
+
+	INFORMIX(Database.INFORMIX, DatabaseDriver.INFORMIX),
+
+	MYSQL(Database.MYSQL, DatabaseDriver.MYSQL),
+
+	ORACLE(Database.ORACLE, DatabaseDriver.ORACLE),
+
+	POSTGRESQL(Database.POSTGRESQL, DatabaseDriver.POSTGRESQL),
+
+	SQL_SERVER(Database.SQL_SERVER, DatabaseDriver.SQLSERVER);
+
+	private final Database database;
+
+	private final DatabaseDriver driver;
+
+	DatabasePlatform(Database database, DatabaseDriver driver) {
+		this.database = database;
+		this.driver = driver;
+	}
+
+	public Database getDatabase() {
+		return this.database;
+	}
+
+	public DatabaseDriver getDriver() {
+		return this.driver;
+	}
+
+	public static DatabasePlatform fromDatabaseDriver(DatabaseDriver driver) {
+		for (DatabasePlatform mapper : values()) {
+			if (mapper.getDriver() == driver) {
+				return mapper;
+			}
+		}
+		return null;
+	}
+
+}

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/orm/jpa/JpaBaseConfiguration.java

@@ -61,6 +61,7 @@ import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter
  * @author Oliver Gierke
  * @author Andy Wilkinson
  * @author Kazuki Shimizu
+ * @author Eddú Meléndez
  */
 @EnableConfigurationProperties(JpaProperties.class)
 @Import(DataSourceInitializedPublisher.Registrar.class)
@@ -101,7 +102,7 @@ public abstract class JpaBaseConfiguration implements BeanFactoryAware {
 	public JpaVendorAdapter jpaVendorAdapter() {
 		AbstractJpaVendorAdapter adapter = createJpaVendorAdapter();
 		adapter.setShowSql(this.properties.isShowSql());
-		adapter.setDatabase(this.properties.getDatabase());
+		adapter.setDatabase(this.properties.determineDatabase(this.dataSource));
 		adapter.setDatabasePlatform(this.properties.getDatabasePlatform());
 		adapter.setGenerateDdl(this.properties.isGenerateDdl());
 		return adapter;

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/orm/jpa/JpaProperties.java

@@ -21,9 +21,15 @@ import java.util.Map;
 
 import javax.sql.DataSource;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
 import org.springframework.boot.autoconfigure.jdbc.EmbeddedDatabaseConnection;
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.boot.context.properties.NestedConfigurationProperty;
+import org.springframework.boot.jdbc.DatabaseDriver;
+import org.springframework.jdbc.support.JdbcUtils;
+import org.springframework.jdbc.support.MetaDataAccessException;
 import org.springframework.orm.jpa.vendor.Database;
 import org.springframework.util.StringUtils;
 
@@ -33,11 +39,14 @@ import org.springframework.util.StringUtils;
  * @author Dave Syer
  * @author Andy Wilkinson
  * @author Stephane Nicoll
+ * @author Eddú Meléndez
  * @since 1.1.0
  */
 @ConfigurationProperties(prefix = "spring.jpa")
 public class JpaProperties {
 
+	private static final Log logger = LogFactory.getLog(JpaProperties.class);
+
 	/**
 	 * Additional native properties to set on the JPA provider.
 	 */
@@ -53,7 +62,7 @@ public class JpaProperties {
 	 * Target database to operate on, auto-detected by default. Can be alternatively set
 	 * using the "databasePlatform" property.
 	 */
-	private Database database = Database.DEFAULT;
+	private Database database;
 
 	/**
 	 * Initialize the schema on startup.
@@ -125,6 +134,31 @@ public class JpaProperties {
 		return this.hibernate.getAdditionalProperties(this.properties, dataSource);
 	}
 
+	/**
+	 * Determine the {@link Database} to use based on this configuration and the primary
+	 * {@link DataSource}.
+	 * @param dataSource the auto-configured data source
+	 * @return {@code Database}
+	 */
+	public Database determineDatabase(DataSource dataSource) {
+		if (this.database != null) {
+			return this.database;
+		}
+		try {
+			String jdbcUrl = (String) JdbcUtils.extractDatabaseMetaData(dataSource,
+					"getURL");
+			DatabasePlatform databasePlatform = DatabasePlatform.fromDatabaseDriver(
+					DatabaseDriver.fromJdbcUrl(jdbcUrl));
+			if (databasePlatform != null) {
+				return databasePlatform.getDatabase();
+			}
+		}
+		catch (MetaDataAccessException ex) {
+			logger.warn("Unable to determine jdbc url from datasource", ex);
+		}
+		return Database.DEFAULT;
+	}
+
 	public static class Hibernate {
 
 		private static final String USE_NEW_ID_GENERATOR_MAPPINGS = "hibernate.id."

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/orm/jpa/CustomHibernateJpaAutoConfigurationTests.java

@@ -16,6 +16,9 @@
 
 package org.springframework.boot.autoconfigure.orm.jpa;
 
+import java.sql.Connection;
+import java.sql.DatabaseMetaData;
+import java.sql.SQLException;
 import java.util.Map;
 
 import javax.sql.DataSource;
@@ -30,15 +33,22 @@ import org.springframework.boot.autoconfigure.jdbc.EmbeddedDataSourceConfigurati
 import org.springframework.boot.autoconfigure.orm.jpa.test.City;
 import org.springframework.boot.test.util.EnvironmentTestUtils;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.orm.jpa.vendor.Database;
+import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
+import org.springframework.test.util.ReflectionTestUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.BDDMockito.mock;
 
 /**
  * Tests for {@link HibernateJpaAutoConfiguration}.
  *
  * @author Dave Syer
  * @author Phillip Webb
+ * @author Eddú Meléndez
  */
 public class CustomHibernateJpaAutoConfigurationTests {
 
@@ -54,7 +64,7 @@ public class CustomHibernateJpaAutoConfigurationTests {
 		// Set up environment so we get a MySQL database but don't require server to be
 		// running...
 		EnvironmentTestUtils.addEnvironment(this.context,
-				"spring.datasource.driverClassName:com.mysql.jdbc.Driver",
+				"spring.datasource.database:mysql",
 				"spring.datasource.url:jdbc:mysql://localhost/nonexistent",
 				"spring.datasource.initialize:false", "spring.jpa.database:MYSQL");
 		this.context.register(TestConfiguration.class, DataSourceAutoConfiguration.class,
@@ -101,10 +111,43 @@ public class CustomHibernateJpaAutoConfigurationTests {
 		assertThat(hibernateProperties.get("hibernate.ejb.naming_strategy")).isNull();
 	}
 
+	@Test
+	public void testDefaultDatabaseForH2() throws Exception {
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"spring.datasource.url:jdbc:h2:mem:testdb",
+				"spring.datasource.initialize:false");
+		this.context.register(TestConfiguration.class, DataSourceAutoConfiguration.class,
+				PropertyPlaceholderAutoConfiguration.class,
+				HibernateJpaAutoConfiguration.class);
+		this.context.refresh();
+		HibernateJpaVendorAdapter bean = this.context.getBean(HibernateJpaVendorAdapter.class);
+		Database database = (Database) ReflectionTestUtils.getField(bean, "database");
+		assertThat(database).isEqualTo(Database.H2);
+	}
+
 	@Configuration
 	@TestAutoConfigurationPackage(City.class)
 	protected static class TestConfiguration {
 
 	}
 
+	@Configuration
+	protected static class MockDataSourceConfiguration {
+
+		@Bean
+		public DataSource dataSource() {
+			DataSource dataSource = mock(DataSource.class);
+			try {
+				given(dataSource.getConnection()).willReturn(mock(Connection.class));
+				given(dataSource.getConnection().getMetaData()).willReturn(
+						mock(DatabaseMetaData.class));
+			}
+			catch (SQLException e) {
+				//Do nothing
+			}
+			return dataSource;
+		}
+
+	}
+
 }

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/orm/jpa/DatabasePlatformTests.java

+/*
+ * Copyright 2012-2016 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
+ *
+ *      http://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.orm.jpa;
+
+import org.junit.Test;
+
+import org.springframework.boot.jdbc.DatabaseDriver;
+import org.springframework.orm.jpa.vendor.Database;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link DatabasePlatform}.
+ *
+ * @author Eddú Meléndez
+ */
+public class DatabasePlatformTests {
+
+	@Test
+	public void databaseDriverLookups() {
+		assertThat(DatabasePlatform.fromDatabaseDriver(DatabaseDriver.DB2))
+				.isEqualTo(DatabasePlatform.DB2);
+		assertThat(DatabasePlatform.fromDatabaseDriver(DatabaseDriver.DERBY))
+				.isEqualTo(DatabasePlatform.DERBY);
+		assertThat(DatabasePlatform.fromDatabaseDriver(DatabaseDriver.H2))
+				.isEqualTo(DatabasePlatform.H2);
+		assertThat(DatabasePlatform.fromDatabaseDriver(DatabaseDriver.HSQLDB))
+				.isEqualTo(DatabasePlatform.HSQL);
+		assertThat(DatabasePlatform.fromDatabaseDriver(DatabaseDriver.INFORMIX))
+				.isEqualTo(DatabasePlatform.INFORMIX);
+		assertThat(DatabasePlatform.fromDatabaseDriver(DatabaseDriver.MYSQL))
+				.isEqualTo(DatabasePlatform.MYSQL);
+		assertThat(DatabasePlatform.fromDatabaseDriver(DatabaseDriver.ORACLE))
+				.isEqualTo(DatabasePlatform.ORACLE);
+		assertThat(DatabasePlatform.fromDatabaseDriver(DatabaseDriver.POSTGRESQL))
+				.isEqualTo(DatabasePlatform.POSTGRESQL);
+		assertThat(DatabasePlatform.fromDatabaseDriver(DatabaseDriver.SQLSERVER))
+				.isEqualTo(DatabasePlatform.SQL_SERVER);
+	}
+
+	@Test
+	public void databaseLookups() {
+		assertThat(DatabasePlatform.fromDatabaseDriver(DatabaseDriver.DB2)
+				.getDatabase())
+				.isEqualTo(Database.DB2);
+		assertThat(DatabasePlatform.fromDatabaseDriver(DatabaseDriver.DERBY)
+				.getDatabase())
+				.isEqualTo(Database.DERBY);
+		assertThat(DatabasePlatform.fromDatabaseDriver(DatabaseDriver.H2)
+				.getDatabase())
+				.isEqualTo(Database.H2);
+		assertThat(DatabasePlatform.fromDatabaseDriver(DatabaseDriver.HSQLDB)
+				.getDatabase())
+				.isEqualTo(Database.HSQL);
+		assertThat(DatabasePlatform.fromDatabaseDriver(DatabaseDriver.INFORMIX)
+				.getDatabase())
+				.isEqualTo(Database.INFORMIX);
+		assertThat(DatabasePlatform.fromDatabaseDriver(DatabaseDriver.MYSQL)
+				.getDatabase())
+				.isEqualTo(Database.MYSQL);
+		assertThat(DatabasePlatform.fromDatabaseDriver(DatabaseDriver.ORACLE)
+				.getDatabase())
+				.isEqualTo(Database.ORACLE);
+		assertThat(DatabasePlatform.fromDatabaseDriver(DatabaseDriver.POSTGRESQL)
+				.getDatabase())
+				.isEqualTo(Database.POSTGRESQL);
+		assertThat(DatabasePlatform.fromDatabaseDriver(DatabaseDriver.SQLSERVER)
+				.getDatabase())
+				.isEqualTo(Database.SQL_SERVER);
+	}
+
+}

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/orm/jpa/JpaPropertiesTests.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.autoconfigure.orm.jpa;
 
+import java.sql.Connection;
+import java.sql.DatabaseMetaData;
 import java.sql.SQLException;
 import java.util.Map;
 
@@ -32,11 +34,14 @@ import org.springframework.boot.orm.jpa.hibernate.SpringPhysicalNamingStrategy;
 import org.springframework.boot.test.util.EnvironmentTestUtils;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.orm.jpa.vendor.Database;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.entry;
 import static org.mockito.BDDMockito.given;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
 
 /**
  * Tests for {@link JpaProperties}.
@@ -166,6 +171,40 @@ public class JpaPropertiesTests {
 				.containsEntry(AvailableSettings.USE_NEW_ID_GENERATOR_MAPPINGS, "true");
 	}
 
+	@Test
+	public void determineDatabaseNoCheckIfDatabaseIsSet() throws SQLException {
+		JpaProperties properties = load(HibernateVersion.V5,
+				"spring.jpa.database=postgresql");
+		DataSource dataSource = mockStandaloneDataSource();
+		Database database = properties.determineDatabase(dataSource);
+		assertThat(database).isEqualTo(Database.POSTGRESQL);
+		verify(dataSource, never()).getConnection();
+	}
+
+	@Test
+	public void determineDatabaseWithKnownUrl() {
+		JpaProperties properties = load(HibernateVersion.V5);
+		Database database = properties.determineDatabase(
+				mockDataSource("jdbc:h2:mem:testdb"));
+		assertThat(database).isEqualTo(Database.H2);
+	}
+
+	@Test
+	public void determineDatabaseWithKnownUrlAndUserConfig() {
+		JpaProperties properties = load(HibernateVersion.V5, "spring.jpa.database=mysql");
+		Database database = properties.determineDatabase(
+				mockDataSource("jdbc:h2:mem:testdb"));
+		assertThat(database).isEqualTo(Database.MYSQL);
+	}
+
+	@Test
+	public void determineDatabaseWithUnknownUrl() {
+		JpaProperties properties = load(HibernateVersion.V5);
+		Database database = properties.determineDatabase(
+				mockDataSource("jdbc:unknown://localhost"));
+		assertThat(database).isEqualTo(Database.DEFAULT);
+	}
+
 	@SuppressWarnings("unchecked")
 	private DataSource mockStandaloneDataSource() throws SQLException {
 		DataSource ds = mock(DataSource.class);
@@ -173,6 +212,21 @@ public class JpaPropertiesTests {
 		return ds;
 	}
 
+	private DataSource mockDataSource(String jdbcUrl) {
+		DataSource ds = mock(DataSource.class);
+		try {
+			DatabaseMetaData metadata = mock(DatabaseMetaData.class);
+			given(metadata.getURL()).willReturn(jdbcUrl);
+			Connection connection = mock(Connection.class);
+			given(connection.getMetaData()).willReturn(metadata);
+			given(ds.getConnection()).willReturn(connection);
+		}
+		catch (SQLException e) {
+			//Do nothing
+		}
+		return ds;
+	}
+
 	private JpaProperties load(HibernateVersion hibernateVersion, String... environment) {
 		HibernateVersion.setRunning(hibernateVersion);
 		AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();

spring-boot-docs/src/main/asciidoc/howto.adoc

@@ -1797,20 +1797,25 @@ annotation, e.g.
 === Configure JPA properties
 Spring Data JPA already provides some vendor-independent configuration options (e.g.
 for SQL logging) and Spring Boot exposes those, and a few more for hibernate as external
-configuration properties. The most common options to set are:
+configuration properties. Some of them are automatically detected according to the context
+so you shouldn't have to set them.
+
+The `spring.jpa.hibernate.ddl-auto` is a special case in that it has different defaults
+depending on whether you are using an embedded database (`create-drop`) or not (`none`).
+The dialect to use is also automatically detected based on the current `DataSource` but
+you can set `spring.jpa.database` yourself if you want to be explicit and bypass that
+check on startup.
+
+The most common options to set are:
 
 [indent=0,subs="verbatim,quotes,attributes"]
 ----
-	spring.jpa.hibernate.ddl-auto=create-drop
 	spring.jpa.hibernate.naming.physical-strategy=com.example.MyPhysicalNamingStrategy
-	spring.jpa.database=H2
 	spring.jpa.show-sql=true
 ----
 
-The `ddl-auto` setting is a special case in that it has different defaults depending on
-whether you are using an embedded database (`create-drop`) or not (`none`). In addition
-all properties in `+spring.jpa.properties.*+` are passed through as normal JPA properties
-(with the prefix stripped) when the local `EntityManagerFactory` is created.
+In addition all properties in `+spring.jpa.properties.*+` are passed through as normal JPA
+properties (with the prefix stripped) when the local `EntityManagerFactory` is created.
 
 Spring Boot provides a consistent naming strategy regardless of the Hibernate generation
 that you are using. If you are using Hibernate 4, you can customize it using