Fix toString, equals and hashCode on accessor proxies (JAVA-495).

olim7t · olim7t · commit 0856b4739412 · 2014-11-07T19:56:10.000+01:00
diff --git a/driver-core/CHANGELOG.rst b/driver-core/CHANGELOG.rst
@@ -6,6 +6,7 @@ CHANGELOG
 
 - [bug] Ignore static fields in mapper (JAVA-510)
 - [bug] Fix UDT parsing at init when using the default protocol version (JAVA-509)
+- [bug] Fix toString, equals and hashCode on accessor proxies (JAVA-495)
 
 Merged from 2.0 branch:
 
diff --git a/driver-mapping/pom.xml b/driver-mapping/pom.xml
@@ -48,6 +48,13 @@
       <scope>test</scope>
     </dependency>
 
+    <dependency>
+      <groupId>org.assertj</groupId>
+      <artifactId>assertj-core</artifactId>
+      <version>1.7.0</version>
+      <scope>test</scope>
+    </dependency>
+
     <dependency>
       <groupId>org.ow2.asm</groupId>
       <artifactId>asm-all</artifactId>
diff --git a/driver-mapping/src/main/java/com/datastax/driver/mapping/AccessorInvocationHandler.java b/driver-mapping/src/main/java/com/datastax/driver/mapping/AccessorInvocationHandler.java
@@ -23,6 +23,19 @@ class AccessorInvocationHandler<T> implements InvocationHandler {
 
     private static final Object[] NO_ARGS = new Object[0];
 
+    private static final Method TO_STRING;
+    private static final Method EQUALS;
+    private static final Method HASH_CODE;
+    static {
+        try {
+            TO_STRING = Object.class.getMethod("toString");
+            EQUALS = Object.class.getMethod("equals", Object.class);
+            HASH_CODE = Object.class.getMethod("hashCode");
+        } catch (NoSuchMethodException e) {
+            throw new AssertionError(e); // Can't happen
+        }
+    }
+
     private final AccessorMapper<T> mapper;
 
     private final Map<Method, MethodMapper> methodMap = new HashMap<Method, MethodMapper>();
@@ -35,11 +48,20 @@ class AccessorInvocationHandler<T> implements InvocationHandler {
     }
 
     public Object invoke(Object proxy, Method m, Object[] args) throws Throwable {
+        if (m.equals(TO_STRING))
+            return mapper.daoClass.getSimpleName() + " implementation generated by the Cassandra driver mapper";
+
+        // It's unlikely that equals and hashCode will be used on accessor implementations, but better safe than sorry.
+        // Identity equality is enough, given that the mapper always returns the same instance for a given accessor.
+        if (m.equals(EQUALS))
+            return proxy == args[0];
+
+        if (m.equals(HASH_CODE))
+            return System.identityHashCode(proxy);
 
         MethodMapper method = methodMap.get(m);
-        if (mapper == null)
+        if (method == null)
             throw new UnsupportedOperationException();
-
         return method.invoke(args == null ? NO_ARGS : args);
     }
 }
diff --git a/driver-mapping/src/test/java/com/datastax/driver/mapping/MapperAccessorTest.java b/driver-mapping/src/test/java/com/datastax/driver/mapping/MapperAccessorTest.java
@@ -0,0 +1,44 @@
+package com.datastax.driver.mapping;
+
+import java.util.Collection;
+
+import com.google.common.collect.Lists;
+import org.testng.annotations.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.datastax.driver.core.CCMBridge;
+import com.datastax.driver.core.ResultSet;
+import com.datastax.driver.mapping.annotations.Accessor;
+import com.datastax.driver.mapping.annotations.Query;
+
+public class MapperAccessorTest extends CCMBridge.PerClassSingleNodeCluster {
+
+    @Override protected Collection<String> getTableDefinitions() {
+        return Lists.newArrayList("CREATE TABLE foo (i int primary key)");
+    }
+
+    @Test(groups = "short")
+    public void should_implement_toString() {
+        SystemAccessor accessor = new MappingManager(session)
+            .createAccessor(SystemAccessor.class);
+
+        assertThat(accessor.toString())
+            .isEqualTo("SystemAccessor implementation generated by the Cassandra driver mapper");
+    }
+
+    @Test(groups = "short")
+    public void should_implement_equals_and_hashCode() {
+        SystemAccessor accessor = new MappingManager(session)
+            .createAccessor(SystemAccessor.class);
+
+        assertThat(accessor).isNotEqualTo(new Object());
+        assertThat(accessor.hashCode()).isEqualTo(System.identityHashCode(accessor));
+    }
+
+    @Accessor
+    public interface SystemAccessor {
+        @Query("select release_version from system.local")
+        ResultSet getCassandraVersion();
+    }
+}
