remove ancient limitation that allowed only one property as UK for 'select' id generator

hibernate-core/src/main/java/org/hibernate/generator/InDatabaseGenerator.java

@@ -15,7 +15,7 @@ import org.hibernate.id.insert.InsertReturningDelegate;
 import org.hibernate.id.insert.UniqueKeySelectingDelegate;
 import org.hibernate.persister.entity.EntityPersister;
 
-import static org.hibernate.generator.internal.NaturalIdHelper.getNaturalIdPropertyName;
+import static org.hibernate.generator.internal.NaturalIdHelper.getNaturalIdPropertyNames;
 
 /**
  * A value generated by the database might be generated implicitly, by a trigger, or using
@@ -116,7 +116,7 @@ public interface InDatabaseGenerator extends Generator {
 		}
 		else {
 			// let's just hope the entity has a @NaturalId!
-			return new UniqueKeySelectingDelegate( persister, dialect, getUniqueKeyPropertyName( persister ) );
+			return new UniqueKeySelectingDelegate( persister, dialect, getUniqueKeyPropertyNames( persister ) );
 		}
 	}
 
@@ -129,8 +129,8 @@ public interface InDatabaseGenerator extends Generator {
 	 * property, if there is one.
 	 */
 	@Incubating
-	default String getUniqueKeyPropertyName(EntityPersister persister) {
+	default String[] getUniqueKeyPropertyNames(EntityPersister persister) {
-		return getNaturalIdPropertyName( persister );
+		return getNaturalIdPropertyNames( persister );
 	}
 
 	default boolean generatedByDatabase() {

hibernate-core/src/main/java/org/hibernate/generator/internal/CurrentTimestampGeneration.java

@@ -7,7 +7,6 @@
 package org.hibernate.generator.internal;
 
 import org.hibernate.AssertionFailure;
-import org.hibernate.Session;
 import org.hibernate.annotations.CreationTimestamp;
 import org.hibernate.annotations.CurrentTimestamp;
 import org.hibernate.annotations.SourceType;

hibernate-core/src/main/java/org/hibernate/generator/internal/NaturalIdHelper.java

@@ -9,27 +9,25 @@ package org.hibernate.generator.internal;
 import org.hibernate.id.IdentifierGenerationException;
 import org.hibernate.persister.entity.EntityPersister;
 
+/**
+ * @author Gavin King
+ */
 public class NaturalIdHelper {
-	public static String getNaturalIdPropertyName(EntityPersister persister) {
+	public static String[] getNaturalIdPropertyNames(EntityPersister persister) {
-		int[] naturalIdPropertyIndices = persister.getNaturalIdentifierProperties();
+		final int[] naturalIdPropertyIndices = persister.getNaturalIdentifierProperties();
 		if ( naturalIdPropertyIndices == null ) {
-			throw new IdentifierGenerationException(
+			throw new IdentifierGenerationException( "entity '" + persister.getEntityName()
-					"no natural-id property defined; " +
+					+ "' has no '@NaturalId' property" );
-							"need to specify [key] in generator parameters"
-			);
-		}
-		if ( naturalIdPropertyIndices.length > 1 ) {
-			throw new IdentifierGenerationException(
-					"generator does not currently support composite natural-id properties;" +
-							" need to specify [key] in generator parameters"
-			);
 		}
 		if ( persister.getEntityMetamodel().isNaturalIdentifierInsertGenerated() ) {
-			throw new IdentifierGenerationException(
+			throw new IdentifierGenerationException( "entity '" + persister.getEntityName()
-					"natural-id also defined as insert-generated; " +
+					+ "' has a '@NaturalId' property which is also defined as insert-generated" );
-							"need to specify [key] in generator parameters"
-			);
 		}
-		return persister.getPropertyNames()[naturalIdPropertyIndices[0]];
+		final String[] allPropertyNames = persister.getPropertyNames();
+		final String[] propertyNames = new String[naturalIdPropertyIndices.length];
+		for ( int i = 0; i < naturalIdPropertyIndices.length; i++ ) {
+			propertyNames[i] = allPropertyNames[naturalIdPropertyIndices[i]];
+		}
+		return propertyNames;
 	}
 }

hibernate-core/src/main/java/org/hibernate/id/PostInsertIdentityPersister.java

@@ -18,14 +18,30 @@ import org.hibernate.persister.entity.mutation.EntityMutationTarget;
 public interface PostInsertIdentityPersister extends EntityPersister, EntityMutationTarget {
 	/**
 	 * Get a SQL select string that performs a select based on a unique
-	 * key determined by the given property name).
+	 * key determined by the given property name.
 	 *
 	 * @param propertyName The name of the property which maps to the
-	 * column(s) to use in the select statement restriction.
+	 *           column(s) to use in the select statement restriction.
 	 * @return The SQL select string
 	 */
 	String getSelectByUniqueKeyString(String propertyName);
 
+	/**
+	 * Get a SQL select string that performs a select based on a unique
+	 * key determined by the given property names.
+	 *
+	 * @param propertyNames The names of the properties which maps to the
+	 *               column(s) to use in the select statement restriction.
+	 * @return The SQL select string
+	 */
+	default String getSelectByUniqueKeyString(String[] propertyNames) {
+		// default impl only for backward compatibility
+		if ( propertyNames.length > 1 ) {
+			throw new IllegalArgumentException( "support for multiple properties not implemented" );
+		}
+		return getSelectByUniqueKeyString( propertyNames[0] );
+	}
+
 	/**
 	 * Get the database-specific SQL command to retrieve the last
 	 * generated IDENTITY value.

hibernate-core/src/main/java/org/hibernate/id/SelectGenerator.java

@@ -15,7 +15,7 @@ import org.hibernate.persister.entity.EntityPersister;
 import org.hibernate.service.ServiceRegistry;
 import org.hibernate.type.Type;
 
-import static org.hibernate.generator.internal.NaturalIdHelper.getNaturalIdPropertyName;
+import static org.hibernate.generator.internal.NaturalIdHelper.getNaturalIdPropertyNames;
 
 /**
  * A generator that {@code select}s the just-{@code insert}ed row to determine the
@@ -82,10 +82,10 @@ public class SelectGenerator
 	}
 
 	@Override
-	public String getUniqueKeyPropertyName(EntityPersister persister) {
+	public String[] getUniqueKeyPropertyNames(EntityPersister persister) {
 		return uniqueKeyPropertyName != null
-				? uniqueKeyPropertyName
+				? new String[] { uniqueKeyPropertyName }
-				: getNaturalIdPropertyName( persister );
+				: getNaturalIdPropertyNames( persister );
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/id/insert/UniqueKeySelectingDelegate.java

@@ -22,25 +22,30 @@ import java.sql.SQLException;
 
 /**
  * Uses a unique key of the inserted entity to locate the newly inserted row.
+ *
+ * @author Gavin King
  */
 public class UniqueKeySelectingDelegate extends AbstractSelectingDelegate {
 	private final PostInsertIdentityPersister persister;
 	private final Dialect dialect;
 
-	private final String uniqueKeyPropertyName;
+	private final String[] uniqueKeyPropertyNames;
-	private final Type uniqueKeyType;
+	private final Type[] uniqueKeyTypes;
 
 	private final String idSelectString;
 
-	public UniqueKeySelectingDelegate(PostInsertIdentityPersister persister, Dialect dialect, String uniqueKeyPropertyName) {
+	public UniqueKeySelectingDelegate(PostInsertIdentityPersister persister, Dialect dialect, String[] uniqueKeyPropertyNames) {
 		super( persister );
 
 		this.persister = persister;
 		this.dialect = dialect;
-		this.uniqueKeyPropertyName = uniqueKeyPropertyName;
+		this.uniqueKeyPropertyNames = uniqueKeyPropertyNames;
 
-		idSelectString = persister.getSelectByUniqueKeyString( uniqueKeyPropertyName );
+		idSelectString = persister.getSelectByUniqueKeyString( uniqueKeyPropertyNames );
-		uniqueKeyType = persister.getPropertyType( uniqueKeyPropertyName );
+		uniqueKeyTypes = new Type[ uniqueKeyPropertyNames.length ];
+		for (int i = 0; i < uniqueKeyPropertyNames.length; i++ ) {
+			uniqueKeyTypes[i] = persister.getPropertyType( uniqueKeyPropertyNames[i] );
+		}
 	}
 
 	protected String getSelectSQL() {
@@ -62,6 +67,10 @@ public class UniqueKeySelectingDelegate extends AbstractSelectingDelegate {
 
 	protected void bindParameters(Object entity, PreparedStatement ps, SharedSessionContractImplementor session)
 			throws SQLException {
-		uniqueKeyType.nullSafeSet( ps, persister.getPropertyValue( entity, uniqueKeyPropertyName ), 1, session );
+		int index = 1;
+		for ( int i = 0; i < uniqueKeyPropertyNames.length; i++ ) {
+			uniqueKeyTypes[i].nullSafeSet( ps, persister.getPropertyValue( entity, uniqueKeyPropertyNames[i] ), index, session );
+			index += uniqueKeyTypes[i].getColumnSpan( session.getFactory() );
+		}
 	}
 }

hibernate-core/src/main/java/org/hibernate/persister/entity/AbstractEntityPersister.java

@@ -2756,11 +2756,19 @@ public abstract class AbstractEntityPersister
 
 	@Override
 	public String getSelectByUniqueKeyString(String propertyName) {
-		return new SimpleSelect( getFactory().getJdbcServices().getDialect() )
+		return getSelectByUniqueKeyString( new String[] { propertyName } );
-				.setTableName( getTableName( 0 ) )
+	}
-				.addColumns( getKeyColumns( 0 ) )
+
-				.addCondition( getPropertyColumnNames( propertyName ), "=?" )
+	@Override
-				.toStatementString();
+	public String getSelectByUniqueKeyString(String[] propertyNames) {
+		final SimpleSelect select =
+				new SimpleSelect( getFactory().getJdbcServices().getDialect() )
+						.setTableName( getTableName(0) )
+						.addColumns( getKeyColumns(0) );
+		for ( int i = 0; i < propertyNames.length; i++ ) {
+			select.addCondition( getPropertyColumnNames( propertyNames[i] ), "= ?" );
+		}
+		return select.toStatementString();
 	}
 
 	/**

hibernate-core/src/main/java/org/hibernate/tuple/entity/EntityMetamodel.java

@@ -672,19 +672,21 @@ public class EntityMetamodel implements Serializable {
 		}
 	}
 
+	/**
+	 * @return {@code true} if one of the properties belonging to the natural id
+	 *         is generated during the execution of an {@code insert} statement
+	 */
 	public boolean isNaturalIdentifierInsertGenerated() {
-		// the intention is for this call to replace the usage of the old ValueInclusion stuff (as exposed from
+		if ( naturalIdPropertyNumbers.length == 0 ) {
-		// persister) in SelectGenerator to determine if it is safe to use the natural identifier to find the
-		// insert-generated identifier.  That wont work if the natural-id is also insert-generated.
-		//
-		// Assumptions:
-		//		* That code checks that there is a natural identifier before making this call, so we assume the same here
-		// 		* That code assumes a non-composite natural-id, so we assume the same here
-		if ( naturalIdPropertyNumbers.length < 1 ) {
 			throw new IllegalStateException( "entity does not have a natural id: " + name );
 		}
-		final Generator strategy = generators[ naturalIdPropertyNumbers[0] ];
+		for ( int i = 0; i < naturalIdPropertyNumbers.length; i++ ) {
-		return strategy != null && strategy.generatesSometimes();
+			final Generator strategy = generators[ naturalIdPropertyNumbers[i] ];
+			if ( strategy != null && strategy.generatesOnInsert() && strategy.generatedOnExecute() ) {
+				return true;
+			}
+		}
+		return false;
 	}
 
 	public boolean isVersionGeneratedByDatabase() {