DATAMONGO-1034 - Explicitly reject incompatible types in MappingMongoConverter.

Improved the exception message that is occurs if the source document contains a BasicDBList but has to be converted into a complex object. We now explicitly hint to use a custom Converter to manually.

Author: odrotbohm

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/MappingMongoConverter.java

@@ -76,6 +76,8 @@
  */
 public class MappingMongoConverter extends AbstractMongoConverter implements ApplicationContextAware {
 
+	private static final String INCOMPATIBLE_TYPES = "Cannot convert %1$s of type %2$s into an instance of %3$s! Implement a custom Converter<%2$s, %3$s> and register it with the CustomConversions. Parent object was: %4$s";
+
 	protected static final Logger LOGGER = LoggerFactory.getLogger(MappingMongoConverter.class);
 
 	protected final MappingContext<? extends MongoPersistentEntity<?>, MongoPersistentProperty> mappingContext;
@@ -214,6 +216,10 @@ protected <S extends Object> S read(TypeInformation<S> type, DBObject dbo, Objec
 			return (S) readMap(typeToUse, dbo, parent);
 		}
 
+		if (dbo instanceof BasicDBList) {
+			throw new MappingException(String.format(INCOMPATIBLE_TYPES, dbo, BasicDBList.class, typeToUse.getType(), parent));
+		}
+
 		// Retrieve persistent entity info
 		MongoPersistentEntity<S> persistentEntity = (MongoPersistentEntity<S>) mappingContext
 				.getPersistentEntity(typeToUse);

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/MappingMongoConverterUnitTests.java

@@ -45,7 +45,9 @@
 import org.joda.time.LocalDate;
 import org.junit.Before;
 import org.junit.Ignore;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 import org.junit.runner.RunWith;
 import org.mockito.Mock;
 import org.mockito.runners.MockitoJUnitRunner;
@@ -99,6 +101,8 @@ public class MappingMongoConverterUnitTests {
 	@Mock ApplicationContext context;
 	@Mock DbRefResolver resolver;
 
+	public @Rule ExpectedException exception = ExpectedException.none();
+
 	@Before
 	public void setUp() {
 
@@ -1839,6 +1843,29 @@ public void shouldUseTargetObjectOfLazyLoadingProxyWhenWriting() {
 		verify(mock, times(1)).initialize();
 	}
 
+	/**
+	 * @see DATAMONGO-1034
+	 */
+	@Test
+	public void rejectsBasicDbListToBeConvertedIntoComplexType() {
+
+		BasicDBList inner = new BasicDBList();
+		inner.add("key");
+		inner.add("value");
+
+		BasicDBList outer = new BasicDBList();
+		outer.add(inner);
+		outer.add(inner);
+
+		BasicDBObject source = new BasicDBObject("attributes", outer);
+
+		exception.expect(MappingException.class);
+		exception.expectMessage(Item.class.getName());
+		exception.expectMessage(BasicDBList.class.getName());
+
+		converter.read(Item.class, source);
+	}
+
 	static class GenericType<T> {
 		T content;
 	}