From 9bf6703c63e85178a53a3bc46231ff44a3a6c570 Mon Sep 17 00:00:00 2001
From: Oliver Gierke <info@olivergierke.de>
Date: Tue, 6 Sep 2011 11:49:07 +0200
Subject: [PATCH] DATADOC-99 - ParameterExpressionProvider now uses parameter
 type instead of handed in type if assignable.

JpaQueryCreator hands Comparable into ParameterExpressionProvider to create ParameterExpression instances for Comparables. The ParameterExpressionProvider in turn now inspects the actual Parameter type and hand this one into the builder in case it's assignable (read: more concrete) to the given type requested.
---
 .../jpa/repository/query/JpaQueryCreator.java | 16 +++---
 .../ParameterExpressionProviderTests.java     | 51 +++++++++++++++++++
 2 files changed, 60 insertions(+), 7 deletions(-)
 create mode 100644 src/test/java/org/springframework/data/jpa/repository/query/ParameterExpressionProviderTests.java

diff --git a/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryCreator.java b/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryCreator.java
index cec67c314..fea701b0f 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryCreator.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryCreator.java
@@ -41,6 +41,7 @@ import org.springframework.data.repository.query.parser.Part.Type;
 import org.springframework.data.repository.query.parser.PartTree;
 import org.springframework.data.repository.query.parser.Property;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 
 /**
  * Query creator to create a {@link CriteriaQuery} from a {@link PartTree}.
@@ -204,7 +205,7 @@ public class JpaQueryCreator extends AbstractQueryCreator<CriteriaQuery<Object>,
 	 * 
 	 * @author Oliver Gierke
 	 */
-	private static class ParameterExpressionProvider {
+	static class ParameterExpressionProvider {
 
 		private final CriteriaBuilder builder;
 		private final Iterator<Parameter> parameters;
@@ -256,10 +257,12 @@ public class JpaQueryCreator extends AbstractQueryCreator<CriteriaQuery<Object>,
 		 * @param type must not be {@literal null}.
 		 * @return
 		 */
-		public <T> ParameterExpression<T> next(Class<T> type) {
+		@SuppressWarnings("unchecked")
+		public <T> ParameterExpression<? extends T> next(Class<T> type) {
 
-			parameters.next();
-			return next(type, null);
+			Parameter parameter = parameters.next();
+			Class<?> typeToUse = ClassUtils.isAssignable(type, parameter.getType()) ? parameter.getType() : type;
+			return (ParameterExpression<? extends T>) next(typeToUse, null);
 		}
 
 		/**
@@ -270,14 +273,13 @@ public class JpaQueryCreator extends AbstractQueryCreator<CriteriaQuery<Object>,
 		 * @param name
 		 * @return
 		 */
-		@SuppressWarnings("unchecked")
 		private <T> ParameterExpression<T> next(Class<T> type, String name) {
 
 			Assert.notNull(type);
 
-			ParameterExpression<?> expression = name == null ? builder.parameter(type) : builder.parameter(type, name);
+			ParameterExpression<T> expression = name == null ? builder.parameter(type) : builder.parameter(type, name);
 			expressions.add(expression);
-			return (ParameterExpression<T>) expression;
+			return expression;
 		}
 	}
 
diff --git a/src/test/java/org/springframework/data/jpa/repository/query/ParameterExpressionProviderTests.java b/src/test/java/org/springframework/data/jpa/repository/query/ParameterExpressionProviderTests.java
new file mode 100644
index 000000000..937a2f745
--- /dev/null
+++ b/src/test/java/org/springframework/data/jpa/repository/query/ParameterExpressionProviderTests.java
@@ -0,0 +1,51 @@
+package org.springframework.data.jpa.repository.query;
+
+import static org.hamcrest.Matchers.*;
+import static org.junit.Assert.*;
+
+import java.lang.reflect.Method;
+
+import javax.persistence.EntityManager;
+import javax.persistence.PersistenceContext;
+import javax.persistence.criteria.ParameterExpression;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.data.jpa.domain.sample.User;
+import org.springframework.data.jpa.repository.query.JpaQueryCreator.ParameterExpressionProvider;
+import org.springframework.data.repository.query.Parameters;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+/**
+ * Integration tests for {@link ParameterExpressionProvider}.
+ * 
+ * @author Oliver Gierke
+ */
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration("classpath:infrastructure.xml")
+public class ParameterExpressionProviderTests {
+
+	@PersistenceContext
+	EntityManager em;
+
+	/**
+	 * @see DATADOC-99
+	 */
+	@Test
+	@SuppressWarnings("rawtypes")
+	public void createsParameterExpressionWithMostConcreteType() throws Exception {
+
+		Method method = SampleRepository.class.getMethod("findByIdGreaterThan", int.class);
+		Parameters parameters = new Parameters(method);
+
+		ParameterExpressionProvider provider = new ParameterExpressionProvider(em.getCriteriaBuilder(), parameters);
+		ParameterExpression<? extends Comparable> expression = provider.next(Comparable.class);
+		assertThat(expression.getParameterType(), is(typeCompatibleWith(int.class)));
+	}
+
+	interface SampleRepository {
+
+		User findByIdGreaterThan(int id);
+	}
+}