DATADOC-130 - Added custom converters for Locale and Character.

Register a custom converter for Locale and Character classes by default as we have to consider them simple (as  they must not be inspected during mapping) but the have to be converted to String values before being handed over to Mongo.

Author: odrotbohm

spring-data-mongodb/src/main/java/org/springframework/data/document/mongodb/convert/AbstractMongoConverter.java

@@ -26,15 +26,18 @@
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 
 import org.bson.types.ObjectId;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.core.GenericTypeResolver;
 import org.springframework.core.convert.ConversionService;
+import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.core.convert.converter.Converter;
 import org.springframework.core.convert.converter.ConverterFactory;
+import org.springframework.core.convert.converter.GenericConverter;
 import org.springframework.core.convert.converter.GenericConverter.ConvertiblePair;
 import org.springframework.core.convert.support.ConversionServiceFactory;
 import org.springframework.core.convert.support.GenericConversionService;
@@ -64,6 +67,7 @@ public AbstractMongoConverter(GenericConversionService conversionService) {
 		this.conversionService = conversionService == null ? ConversionServiceFactory.createDefaultConversionService()
 				: conversionService;
 		this.conversionService.removeConvertible(Object.class, String.class);
+		registerConverter(CustomToStringConverter.INSTANCE);
 	}
 
 	/**
@@ -107,19 +111,33 @@ private void initializeConverters() {
 	 * @param converter
 	 */
 	private void registerConverter(Object converter) {
-		Class<?>[] arguments = GenericTypeResolver.resolveTypeArguments(converter.getClass(), Converter.class);
-		if (MONGO_TYPES.contains(arguments[1]) || MONGO_TYPES.contains(arguments[0])) {
-			customTypeMapping.add(new ConvertiblePair(arguments[0], arguments[1]));
+		
+		if (converter instanceof GenericConverter) {
+			customTypeMapping.addAll(((GenericConverter) converter).getConvertibleTypes());
+		} else {
+			Class<?>[] arguments = GenericTypeResolver.resolveTypeArguments(converter.getClass(), Converter.class);
+			if (MONGO_TYPES.contains(arguments[1]) || MONGO_TYPES.contains(arguments[0])) {
+				customTypeMapping.add(new ConvertiblePair(arguments[0], arguments[1]));
+			}
 		}
+		
 		boolean added = false;
+		
 		if (converter instanceof Converter) {
 			this.conversionService.addConverter((Converter<?, ?>) converter);
 			added = true;
 		}
+		
 		if (converter instanceof ConverterFactory) {
 			this.conversionService.addConverterFactory((ConverterFactory<?, ?>) converter);
 			added = true;
 		}
+		
+		if (converter instanceof GenericConverter) {
+			this.conversionService.addConverter((GenericConverter) converter);
+			added = true;
+		}
+		
 		if (!added) {
 			throw new IllegalArgumentException("Given set contains element that is neither Converter nor ConverterFactory!");
 		}
@@ -222,4 +240,19 @@ public BasicDBList maybeConvertList(BasicDBList dbl) {
 		}
 		return newDbl;
 	}
+
+	
+	private enum CustomToStringConverter implements GenericConverter  {
+		INSTANCE;
+
+		public Set<ConvertiblePair> getConvertibleTypes() {
+			ConvertiblePair localeToString = new ConvertiblePair(Locale.class, String.class);
+			ConvertiblePair booleanToString = new ConvertiblePair(Character.class, String.class);
+			return new HashSet<ConvertiblePair>(Arrays.asList(localeToString, booleanToString));
+		}
+
+		public Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
+			return source.toString();
+		}
+	}
 }

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

@@ -559,7 +559,14 @@ public TypeInformation<?> getValueType(TypeInformation<?> type) {
 	 */
 	private void writeSimpleInternal(String key, Object value, DBObject dbObject) {
 
-		Object valueToSet = value.getClass().isEnum() ? ((Enum<?>) value).name() : value;
+		Class<?> customTarget = getCustomTarget(value.getClass(), null);
+		
+		Object valueToSet = null;
+		if (customTarget != null) {
+			valueToSet = conversionService.convert(value, customTarget);
+		} else {
+			valueToSet = value.getClass().isEnum() ? ((Enum<?>) value).name() : value;
+		}
 		dbObject.put(key, valueToSet);
 	}
 

spring-data-mongodb/src/test/java/org/springframework/data/document/mongodb/mapping/MappingMongoConverterUnitTests.java

@@ -269,6 +269,21 @@ public void readsCollectionWithInterfaceCorrectly() {
 
 	}
 
+	@Test
+	public void convertsLocalesOutOfTheBox() {
+		LocaleWrapper wrapper = new LocaleWrapper();
+		wrapper.locale = Locale.US;
+		
+		DBObject dbObject = new BasicDBObject();
+		converter.write(wrapper, dbObject);
+		
+		Object localeField = dbObject.get("locale");
+		assertThat(localeField, is(String.class));
+		assertThat((String) localeField, is("en_US"));
+		
+		LocaleWrapper read = converter.read(LocaleWrapper.class, dbObject);
+		assertThat(read.locale, is(Locale.US));
+	}
 
 	class ClassWithEnumProperty {
 
@@ -307,6 +322,10 @@ class CollectionWrapper {
 		List<Contact> contacts;
 	}
 
+	class LocaleWrapper {
+		Locale locale;
+	}
+	
 	private class LocalDateToDateConverter implements Converter<LocalDate, Date> {
 
 		public Date convert(LocalDate source) {