DATAJDBC-241 - Support for immutable entities.

Immutable entities can now be saved and loaded and the immutability will be honored.

This feature is currently limited to a single level of reference.

In order to implement this the logic for updating IDs with those generated from the database got moved out of the DefaultDataAccessStrategy into the AggregateChange.
As part of that move DataAccessStrategy.save now returns a generated id, if available.

See also: DATAJDBC-248.

Author: schauder

src/main/java/org/springframework/data/jdbc/core/CascadingDataAccessStrategy.java

@@ -43,7 +43,7 @@ public CascadingDataAccessStrategy(List<DataAccessStrategy> strategies) {
 	 * @see org.springframework.data.jdbc.core.DataAccessStrategy#insert(java.lang.Object, java.lang.Class, java.util.Map)
 	 */
 	@Override
-	public <T> T insert(T instance, Class<T> domainType, Map<String, Object> additionalParameters) {
+	public <T> Object insert(T instance, Class<T> domainType, Map<String, Object> additionalParameters) {
 		return collect(das -> das.insert(instance, domainType, additionalParameters));
 	}
 

src/main/java/org/springframework/data/jdbc/core/DataAccessStrategy.java

@@ -38,10 +38,9 @@ public interface DataAccessStrategy {
 	 * @param additionalParameters name-value pairs of additional parameters. Especially ids of parent entities that need
 	 *          to get referenced are contained in this map. Must not be {@code null}.
 	 * @param <T> the type of the instance.
-	 * @return the instance after insert into. The returned instance may be different to the given {@code instance} as
-	 *         this method can apply changes to the return object.
+	 * @return the id generated by the database if any.
 	 */
-	<T> T insert(T instance, Class<T> domainType, Map<String, Object> additionalParameters);
+	<T> Object insert(T instance, Class<T> domainType, Map<String, Object> additionalParameters);
 
 	/**
 	 * Updates the data of a single entity in the database. Referenced entities don't get handled.

src/main/java/org/springframework/data/jdbc/core/DefaultDataAccessStrategy.java

@@ -21,13 +21,11 @@
 import java.util.HashMap;
 import java.util.LinkedHashMap;
 import java.util.Map;
-import java.util.Optional;
 import java.util.stream.Collectors;
 import java.util.stream.StreamSupport;
 
 import org.springframework.dao.EmptyResultDataAccessException;
 import org.springframework.dao.InvalidDataAccessApiUsageException;
-import org.springframework.dao.NonTransientDataAccessException;
 import org.springframework.data.jdbc.support.JdbcUtil;
 import org.springframework.data.mapping.PersistentPropertyAccessor;
 import org.springframework.data.mapping.PersistentPropertyPath;
@@ -83,7 +81,7 @@ public DefaultDataAccessStrategy(SqlGeneratorSource sqlGeneratorSource, Relation
 	 * @see org.springframework.data.jdbc.core.DataAccessStrategy#insert(java.lang.Object, java.lang.Class, java.util.Map)
 	 */
 	@Override
-	public <T> T insert(T instance, Class<T> domainType, Map<String, Object> additionalParameters) {
+	public <T> Object insert(T instance, Class<T> domainType, Map<String, Object> additionalParameters) {
 
 		KeyHolder holder = new GeneratedKeyHolder();
 		RelationalPersistentEntity<T> persistentEntity = getRequiredPersistentEntity(domainType);
@@ -110,16 +108,7 @@ public <T> T insert(T instance, Class<T> domainType, Map<String, Object> additio
 				holder //
 		);
 
-		instance = setIdFromJdbc(instance, holder, persistentEntity);
-
-		// if there is an id property and it was null before the save
-		// The database should have created an id and provided it.
-
-		if (idProperty != null && idValue == null && persistentEntity.isNew(instance)) {
-			throw new IllegalStateException(String.format(ENTITY_NEW_AFTER_INSERT, persistentEntity));
-		}
-
-		return instance;
+		return getIdFromHolder(holder, persistentEntity);
 	}
 
 	/*
@@ -327,41 +316,20 @@ private static <S, ID> boolean isIdPropertyNullOrScalarZero(@Nullable ID idValue
 				|| (idProperty.getType() == long.class && idValue.equals(0L));
 	}
 
-	private <S> S setIdFromJdbc(S instance, KeyHolder holder, RelationalPersistentEntity<S> persistentEntity) {
-
-		try {
-
-			PersistentPropertyAccessor<S> accessor = converter.getPropertyAccessor(persistentEntity, instance);
-
-			getIdFromHolder(holder, persistentEntity).ifPresent(it -> {
-
-				RelationalPersistentProperty idProperty = persistentEntity.getRequiredIdProperty();
-
-				accessor.setProperty(idProperty, it);
-
-			});
-
-			return accessor.getBean();
-
-		} catch (NonTransientDataAccessException e) {
-			throw new UnableToSetId("Unable to set id of " + instance, e);
-		}
-	}
-
-	private <S> Optional<Object> getIdFromHolder(KeyHolder holder, RelationalPersistentEntity<S> persistentEntity) {
+	private <S> Object getIdFromHolder(KeyHolder holder, RelationalPersistentEntity<S> persistentEntity) {
 
 		try {
 			// MySQL just returns one value with a special name
-			return Optional.ofNullable(holder.getKey());
+			return holder.getKey();
 		} catch (InvalidDataAccessApiUsageException e) {
 			// Postgres returns a value for each column
 			Map<String, Object> keys = holder.getKeys();
 
 			if (keys == null || persistentEntity.getIdProperty() == null) {
-				return Optional.empty();
+				return null;
 			}
 
-			return Optional.ofNullable(keys.get(persistentEntity.getIdColumn()));
+			return keys.get(persistentEntity.getIdColumn());
 		}
 	}
 

src/main/java/org/springframework/data/jdbc/core/DefaultJdbcInterpreter.java

@@ -58,8 +58,9 @@ class DefaultJdbcInterpreter implements Interpreter {
 	@Override
 	public <T> void interpret(Insert<T> insert) {
 
-		T entity = accessStrategy.insert(insert.getEntity(), insert.getEntityType(), createAdditionalColumnValues(insert));
-		insert.setResultingEntity(entity);
+		Object id = accessStrategy.insert(insert.getEntity(), insert.getEntityType(), createAdditionalColumnValues(insert));
+
+		insert.setGeneratedId(id);
 	}
 
 	/*
@@ -69,16 +70,16 @@ public <T> void interpret(Insert<T> insert) {
 	@Override
 	public <T> void interpret(InsertRoot<T> insert) {
 
-		T entity = accessStrategy.insert(insert.getEntity(), insert.getEntityType(), Collections.emptyMap());
-		insert.setResultingEntity(entity);
+		Object id = accessStrategy.insert(insert.getEntity(), insert.getEntityType(), Collections.emptyMap());
+		insert.setGeneratedId(id);
 	}
 
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.relational.core.conversion.Interpreter#interpret(org.springframework.data.relational.core.conversion.DbAction.Update)
 	 */
 	@Override
-	public <T> void interpret(Update<T> update) {
+	public <T> void interpret(Update<T> update ) {
 		accessStrategy.update(update.getEntity(), update.getEntityType());
 	}
 
@@ -169,8 +170,8 @@ private Object getIdFromEntityDependingOn(DbAction.WithEntity<?> dependingOn,
 
 		Object entity = dependingOn.getEntity();
 
-		if (dependingOn instanceof DbAction.WithResultEntity) {
-			entity = ((DbAction.WithResultEntity<?>) dependingOn).getResultingEntity();
+		if (dependingOn instanceof DbAction.WithGeneratedId) {
+			return  ((DbAction.WithGeneratedId<?>) dependingOn).getGeneratedId();
 		}
 
 		return persistentEntity.getIdentifierAccessor(entity).getIdentifier();

src/main/java/org/springframework/data/jdbc/core/DelegatingDataAccessStrategy.java

@@ -36,7 +36,7 @@ public class DelegatingDataAccessStrategy implements DataAccessStrategy {
 	 * @see org.springframework.data.jdbc.core.DataAccessStrategy#insert(java.lang.Object, java.lang.Class, java.util.Map)
 	 */
 	@Override
-	public <T> T insert(T instance, Class<T> domainType, Map<String, Object> additionalParameters) {
+	public <T> Object insert(T instance, Class<T> domainType, Map<String, Object> additionalParameters) {
 		return delegate.insert(instance, domainType, additionalParameters);
 	}
 

src/main/java/org/springframework/data/jdbc/core/JdbcAggregateTemplate.java

@@ -22,6 +22,7 @@
 import org.springframework.data.relational.core.conversion.AggregateChange;
 import org.springframework.data.relational.core.conversion.AggregateChange.Kind;
 import org.springframework.data.relational.core.conversion.Interpreter;
+import org.springframework.data.relational.core.conversion.RelationalConverter;
 import org.springframework.data.relational.core.conversion.RelationalEntityDeleteWriter;
 import org.springframework.data.relational.core.conversion.RelationalEntityWriter;
 import org.springframework.data.relational.core.mapping.RelationalMappingContext;
@@ -46,6 +47,7 @@ public class JdbcAggregateTemplate implements JdbcAggregateOperations {
 
 	private final ApplicationEventPublisher publisher;
 	private final RelationalMappingContext context;
+	private final RelationalConverter converter;
 	private final Interpreter interpreter;
 
 	private final RelationalEntityWriter jdbcEntityWriter;
@@ -62,14 +64,16 @@ public class JdbcAggregateTemplate implements JdbcAggregateOperations {
 	 * @param dataAccessStrategy must not be {@literal null}.
 	 */
 	public JdbcAggregateTemplate(ApplicationEventPublisher publisher, RelationalMappingContext context,
-			DataAccessStrategy dataAccessStrategy) {
+			RelationalConverter converter, DataAccessStrategy dataAccessStrategy) {
 
 		Assert.notNull(publisher, "ApplicationEventPublisher must not be null!");
 		Assert.notNull(context, "RelationalMappingContext must not be null!");
+		Assert.notNull(converter, "RelationalConverter must not be null!");
 		Assert.notNull(dataAccessStrategy, "DataAccessStrategy must not be null!");
 
 		this.publisher = publisher;
 		this.context = context;
+		this.converter = converter;
 		this.accessStrategy = dataAccessStrategy;
 
 		this.jdbcEntityWriter = new RelationalEntityWriter(context);
@@ -86,8 +90,8 @@ public <T> T save(T instance) {
 
 		Assert.notNull(instance, "Aggregate instance must not be null!");
 
-		RelationalPersistentEntity<?> entity = context.getRequiredPersistentEntity(instance.getClass());
-		IdentifierAccessor identifierAccessor = entity.getIdentifierAccessor(instance);
+		RelationalPersistentEntity<?> persistentEntity = context.getRequiredPersistentEntity(instance.getClass());
+		IdentifierAccessor identifierAccessor = persistentEntity.getIdentifierAccessor(instance);
 
 		AggregateChange<T> change = createChange(instance);
 
@@ -97,9 +101,9 @@ public <T> T save(T instance) {
 				change //
 		));
 
-		change.executeWith(interpreter);
+		change.executeWith(interpreter, context, converter);
 
-		Object identifier = entity.getIdentifierAccessor(change.getEntity()).getIdentifier();
+		Object identifier = persistentEntity.getIdentifierAccessor(change.getEntity()).getIdentifier();
 
 		Assert.notNull(identifier, "After saving the identifier must not be null");
 
@@ -198,7 +202,7 @@ public <S> void deleteById(Object id, Class<S> domainType) {
 	public void deleteAll(Class<?> domainType) {
 
 		AggregateChange<?> change = createDeletingChange(domainType);
-		change.executeWith(interpreter);
+		change.executeWith(interpreter, context, converter);
 	}
 
 	private void deleteTree(Object id, @Nullable Object entity, Class<?> domainType) {
@@ -209,7 +213,7 @@ private void deleteTree(Object id, @Nullable Object entity, Class<?> domainType)
 		Optional<Object> optionalEntity = Optional.ofNullable(entity);
 		publisher.publishEvent(new BeforeDeleteEvent(specifiedId, optionalEntity, change));
 
-		change.executeWith(interpreter);
+		change.executeWith(interpreter, context, converter);
 
 		publisher.publishEvent(new AfterDeleteEvent(specifiedId, optionalEntity, change));
 	}

src/main/java/org/springframework/data/jdbc/mybatis/MyBatisDataAccessStrategy.java

@@ -128,12 +128,13 @@ public void setNamespaceStrategy(NamespaceStrategy namespaceStrategy) {
 	 * @see org.springframework.data.jdbc.core.DataAccessStrategy#insert(java.lang.Object, java.lang.Class, java.util.Map)
 	 */
 	@Override
-	public <T> T insert(T instance, Class<T> domainType, Map<String, Object> additionalParameters) {
-		
+	public <T> Object insert(T instance, Class<T> domainType, Map<String, Object> additionalParameters) {
+
+		MyBatisContext myBatisContext = new MyBatisContext(null, instance, domainType, additionalParameters);
 		sqlSession().insert(namespace(domainType) + ".insert",
-				new MyBatisContext(null, instance, domainType, additionalParameters));
+				myBatisContext);
 
-		return instance;
+		return myBatisContext.getId();
 	}
 
 	/* 

src/main/java/org/springframework/data/jdbc/repository/support/JdbcRepositoryFactory.java

@@ -104,7 +104,7 @@ public <T, ID> EntityInformation<T, ID> getEntityInformation(Class<T> aClass) {
 	@Override
 	protected Object getTargetRepository(RepositoryInformation repositoryInformation) {
 
-		JdbcAggregateTemplate template = new JdbcAggregateTemplate(publisher, context, accessStrategy);
+		JdbcAggregateTemplate template = new JdbcAggregateTemplate(publisher, context, converter, accessStrategy);
 
 		return new SimpleJdbcRepository<>(template, context.getPersistentEntity(repositoryInformation.getDomainType()));
 	}