HHH-15228 ("RoundFunction" which extends StandardSQLFunction to return BigDecimal)

hibernate-core/src/main/java/org/hibernate/dialect/H2Dialect.java

@@ -15,6 +15,7 @@
 import org.hibernate.cfg.AvailableSettings;
 import org.hibernate.dialect.function.AvgWithArgumentCastFunction;
 import org.hibernate.dialect.function.NoArgSQLFunction;
+import org.hibernate.dialect.function.RoundFunction;
 import org.hibernate.dialect.function.StandardSQLFunction;
 import org.hibernate.dialect.function.VarArgsSQLFunction;
 import org.hibernate.dialect.hint.IndexQueryHintHandler;
@@ -163,7 +164,7 @@ public H2Dialect() {
 		registerFunction( "power", new StandardSQLFunction( "power", StandardBasicTypes.DOUBLE ) );
 		registerFunction( "radians", new StandardSQLFunction( "radians", StandardBasicTypes.DOUBLE ) );
 		registerFunction( "rand", new NoArgSQLFunction( "rand", StandardBasicTypes.DOUBLE ) );
-		registerFunction( "round", new StandardSQLFunction( "round", StandardBasicTypes.DOUBLE ) );
+		registerFunction( "round", new RoundFunction( "round" ) );
 		registerFunction( "roundmagic", new StandardSQLFunction( "roundmagic", StandardBasicTypes.DOUBLE ) );
 		registerFunction( "sign", new StandardSQLFunction( "sign", StandardBasicTypes.INTEGER ) );
 		registerFunction( "sin", new StandardSQLFunction( "sin", StandardBasicTypes.DOUBLE ) );
@@ -425,12 +426,12 @@ public boolean doesReadCommittedCauseWritersToBlockReaders() {
 		// see http://groups.google.com/group/h2-database/browse_thread/thread/562d8a49e2dabe99?hl=en
 		return true;
 	}
-	
+
 	@Override
 	public boolean supportsTuplesInSubqueries() {
 		return false;
 	}
-	
+
 	@Override
 	public boolean dropConstraints() {
 		// We don't need to drop constraints before dropping tables, that just leads to error

hibernate-core/src/main/java/org/hibernate/dialect/function/RoundFunction.java

@@ -0,0 +1,38 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
+
+package org.hibernate.dialect.function;
+
+import org.hibernate.engine.spi.Mapping;
+import org.hibernate.type.StandardBasicTypes;
+import org.hibernate.type.Type;
+
+/**
+ * When there is need to use round function with other function (i.e.sum()),
+ * its return type becomes Double by default if it is registered as a StandardSQLFunction.
+ * This function provides the feasibility to return BigDecimal as return type if argument is
+ * BigDecimal
+ *
+ * @author Mayur Bhindi
+ */
+public class RoundFunction extends StandardSQLFunction {
+
+	/**
+	 * Constructs RoundFunction
+	 *
+	 * @param name
+	 */
+	public RoundFunction(String name) {
+		super( name );
+	}
+
+	@Override
+	public Type getReturnType(Type firstArgumentType, Mapping mapping) {
+		return firstArgumentType == StandardBasicTypes.BIG_DECIMAL ? firstArgumentType : StandardBasicTypes.DOUBLE;
+	}
+
+}

hibernate-core/src/test/java/org/hibernate/dialect/H2DialectTest.java

@@ -0,0 +1,48 @@
+package org.hibernate.dialect;
+
+import java.util.Map;
+
+import org.hibernate.dialect.function.SQLFunction;
+import org.hibernate.type.StandardBasicTypes;
+
+import org.hibernate.testing.TestForIssue;
+import org.hibernate.testing.junit4.BaseUnitTestCase;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Unit test of the behavior of the H2Dialect
+ *
+ * @author Mayur Bhindi
+ */
+public class H2DialectTest {
+
+	private H2Dialect dialect;
+
+	@Before
+	public void setup() {
+		dialect = new H2Dialect();
+	}
+
+	@After
+	public void tearDown() {
+		dialect = null;
+	}
+
+	@Test
+	@TestForIssue(jiraKey = "HHH-15228")
+	public void testRoundFunction() {
+		Map<String, SQLFunction> functions = dialect.getFunctions();
+		SQLFunction sqlFunction = functions.get( "round" );
+		assertEquals( StandardBasicTypes.DOUBLE, sqlFunction.getReturnType( null, null ) );
+		assertEquals( StandardBasicTypes.DOUBLE, sqlFunction.getReturnType( StandardBasicTypes.INTEGER, null ) );
+		assertEquals(
+				StandardBasicTypes.BIG_DECIMAL,
+				sqlFunction.getReturnType( StandardBasicTypes.BIG_DECIMAL, null )
+		);
+
+	}
+}