DATACMNS-820 - Allow setter invocations in projections backed by beans.

Invocations to setter methods are now passed to the backing bean.

Original pull request: #155.

src/main/java/org/springframework/data/projection/PropertyAccessingMethodInterceptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2015 the original author or authors.
+ * Copyright 2014-2016 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.
@@ -30,6 +30,7 @@ import org.springframework.util.ReflectionUtils;
  * Method interceptor to forward a delegation to bean property accessor methods to the property of a given target.
  * 
  * @author Oliver Gierke
+ * @author Mark Paluch
  * @since 1.10
  */
 class PropertyAccessingMethodInterceptor implements MethodInterceptor {
@@ -66,6 +67,20 @@ class PropertyAccessingMethodInterceptor implements MethodInterceptor {
 			throw new IllegalStateException("Invoked method is not a property accessor!");
 		}
 
+        if (isSetterMethod(method, descriptor)) {
+            if (invocation.getArguments().length != 1) {
+                throw new IllegalStateException("Invoked setter method requires exactly one argument!");
+            }
+
+            target.setPropertyValue(descriptor.getName(), invocation.getArguments()[0]);
+            return null;
+        }
+
 		return target.getPropertyValue(descriptor.getName());
 	}
+
+	private boolean isSetterMethod(Method method, PropertyDescriptor descriptor) {
+		return method.equals(descriptor.getWriteMethod());
+	}
+
 }

src/test/java/org/springframework/data/projection/PropertyAccessingMethodInterceptorUnitTests.java

@@ -26,6 +26,7 @@ import org.junit.runner.RunWith;
 import org.mockito.Mock;
 import org.mockito.runners.MockitoJUnitRunner;
 import org.springframework.beans.NotReadablePropertyException;
+import org.springframework.beans.NotWritablePropertyException;
 
 /**
  * Unit tests for {@link PropertyAccessingMethodInterceptor}.
@@ -62,6 +63,50 @@ public class PropertyAccessingMethodInterceptorUnitTests {
 		new PropertyAccessingMethodInterceptor(new Source()).invoke(invocation);
 	}
 
+    /**
+     * @see DATACMNS-820
+     */
+    @Test
+    public void triggersWritePropertyAccessOnTarget() throws Throwable {
+
+        Source source = new Source();
+        source.firstname = "Dave";
+
+        when(invocation.getMethod()).thenReturn(Projection.class.getMethod("setFirstname", String.class));
+        when(invocation.getArguments()).thenReturn(new Object[] { "Carl" });
+        MethodInterceptor interceptor = new PropertyAccessingMethodInterceptor(source);
+
+        interceptor.invoke(invocation);
+
+        assertThat(source.firstname, is((Object) "Carl"));
+    }
+
+    /**
+     * @see DATACMNS-820
+     */
+    @Test(expected = IllegalStateException.class)
+    public void throwsAppropriateExceptionIfTheInvocationHasNoArguments() throws Throwable {
+
+        Source source = new Source();
+
+        when(invocation.getMethod()).thenReturn(Projection.class.getMethod("setFirstname", String.class));
+        when(invocation.getArguments()).thenReturn(new Object[0]);
+        MethodInterceptor interceptor = new PropertyAccessingMethodInterceptor(source);
+
+        interceptor.invoke(invocation);
+    }
+
+    /**
+     * @see DATACMNS-820
+     */
+    @Test(expected = NotWritablePropertyException.class)
+    public void throwsAppropriateExceptionIfThePropertyCannotWritten() throws Throwable {
+
+        when(invocation.getMethod()).thenReturn(Projection.class.getMethod("setGarbage", String.class));
+        when(invocation.getArguments()).thenReturn(new Object[] { "Carl" });
+        new PropertyAccessingMethodInterceptor(new Source()).invoke(invocation);
+    }
+
 	/**
 	 * @see DATAREST-221
 	 */
@@ -91,6 +136,10 @@ public class PropertyAccessingMethodInterceptorUnitTests {
 
 		String getFirstname();
 
+		void setFirstname(String firstname);
+
+		void setGarbage(String garbage);
+
 		String getLastname();
 
 		String someGarbage();

src/test/java/org/springframework/data/projection/SpelAwareProxyProjectionFactoryUnitTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015 the original author or authors.
+ * Copyright 2015-2016 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.
@@ -22,6 +22,7 @@ import java.util.List;
 
 import org.junit.Before;
 import org.junit.Test;
+import org.springframework.beans.NotWritablePropertyException;
 import org.springframework.beans.factory.annotation.Value;
 
 /**
@@ -29,6 +30,7 @@ import org.springframework.beans.factory.annotation.Value;
  * 
  * @author Oliver Gierke
  * @author Thomas Darimont
+ * @author Mark Paluch
  */
 public class SpelAwareProxyProjectionFactoryUnitTests {
 
@@ -53,6 +55,42 @@ public class SpelAwareProxyProjectionFactoryUnitTests {
 		assertThat(excerpt.getFullName(), is("Dave Matthews"));
 	}
 
+	/**
+	 * @see DATACMNS-820
+	 */
+	@Test
+	public void setsValueUsingProjection() {
+
+		Customer customer = new Customer();
+		customer.firstname = "Dave";
+
+		CustomerExcerpt excerpt = factory.createProjection(CustomerExcerpt.class, customer);
+		excerpt.setFirstname("Carl");
+
+		assertThat(customer.firstname, is("Carl"));
+	}
+
+	/**
+	 * @see DATACMNS-820
+	 */
+	@Test
+	public void settingNotWriteablePropertyFails() {
+
+		Customer customer = new Customer();
+		customer.firstname = "Dave";
+
+		ProjectionWithNotWriteableProperty projection = factory.createProjection(ProjectionWithNotWriteableProperty.class,
+				customer);
+
+		try {
+			projection.setFirstName("Carl");
+			fail("Missing NotWritablePropertyException");
+		} catch (NotWritablePropertyException e) {
+			assertThat(e, instanceOf(NotWritablePropertyException.class));
+		}
+
+	}
+
 	/**
 	 * @see DATACMNS-630
 	 */
@@ -87,5 +125,12 @@ public class SpelAwareProxyProjectionFactoryUnitTests {
 		String getFullName();
 
 		String getFirstname();
+
+		void setFirstname(String firstname);
+	}
+
+	interface ProjectionWithNotWriteableProperty {
+
+		void setFirstName(String firstname);
 	}
 }