DATAMONGO-1118 - MappingMongoConverter now uses custom conversions for Map keys, too.

We now allow conversions of map keys using custom Converter implementations if the conversion target type is a String.

Original pull request: #260.

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

@@ -646,9 +646,8 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 			Object key = entry.getKey();
 			Object val = entry.getValue();
 			if (conversions.isSimpleType(key.getClass())) {
-				// Don't use conversion service here as removal of ObjectToString converter results in some primitive types not
-				// being convertable
-				String simpleKey = potentiallyEscapeMapKey(key.toString());
+
+				String simpleKey = potentiallyConvertMapKey(key);
 				if (val == null || conversions.isSimpleType(val.getClass())) {
 					writeSimpleInternal(val, dbo, simpleKey);
 				} else if (val instanceof Collection || val.getClass().isArray()) {
@@ -669,6 +668,20 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 		return dbo;
 	}
 
+	private String potentiallyConvertMapKey(Object key) {
+
+		String stringKey = null;
+		if (key instanceof String
+				|| !(conversions.hasCustomWriteTarget(key.getClass()) && conversions.getCustomWriteTarget(key.getClass())
+						.equals(String.class))) {
+			stringKey = key.toString();
+		} else {
+			stringKey = (String) getPotentiallyConvertedSimpleWrite(key);
+		}
+
+		return potentiallyEscapeMapKey(stringKey);
+	}
+
 	/**
 	 * Potentially replaces dots in the given map key with the configured map key replacement if configured or aborts
 	 * conversion if none is configured.

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

@@ -56,12 +56,15 @@ import org.mockito.Mock;
 import org.mockito.Mockito;
 import org.mockito.runners.MockitoJUnitRunner;
 import org.springframework.aop.framework.ProxyFactory;
+import org.springframework.beans.ConversionNotSupportedException;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.context.ApplicationContext;
 import org.springframework.core.convert.converter.Converter;
 import org.springframework.data.annotation.Id;
 import org.springframework.data.annotation.PersistenceConstructor;
 import org.springframework.data.annotation.TypeAlias;
+import org.springframework.data.convert.ReadingConverter;
+import org.springframework.data.convert.WritingConverter;
 import org.springframework.data.geo.Box;
 import org.springframework.data.geo.Circle;
 import org.springframework.data.geo.Distance;
@@ -1964,6 +1967,7 @@ public class MappingMongoConverterUnitTests {
 		assertThat(converter.read(TypeWithLocalDateTime.class, result).date, is(reference));
 	}
 
+
 	/**
 	 * @see DATAMONGO-1128
 	 */
@@ -2001,6 +2005,68 @@ public class MappingMongoConverterUnitTests {
 		assertThat(read.localDateTime, is(Optional.of(now)));
 	}
 
+	/**
+	 * @see DATAMONGO-1118
+	 */
+	@Test
+	public void convertsMapKeyUsingCustomConverterForAndBackwards() {
+
+		MappingMongoConverter converter = new MappingMongoConverter(resolver, mappingContext);
+		converter.setCustomConversions(new CustomConversions(Arrays.asList(new FooBarEnumToStringConverter(),
+				new StringToFooNumConverter())));
+		converter.afterPropertiesSet();
+
+		ClassWithMapUsingEnumAsKey source = new ClassWithMapUsingEnumAsKey();
+		source.map = new HashMap<MappingMongoConverterUnitTests.FooBarEnum, String>();
+		source.map.put(FooBarEnum.FOO, "wohoo");
+
+		DBObject target = new BasicDBObject();
+		converter.write(source, target);
+
+		assertThat(converter.read(ClassWithMapUsingEnumAsKey.class, target).map, equalTo(source.map));
+	}
+
+	/**
+	 * @see DATAMONGO-1118
+	 */
+	@Test
+	public void writesMapKeyUsingCustomConverter() {
+
+		MappingMongoConverter converter = new MappingMongoConverter(resolver, mappingContext);
+		converter.setCustomConversions(new CustomConversions(Arrays.asList(new FooBarEnumToStringConverter())));
+		converter.afterPropertiesSet();
+
+		ClassWithMapUsingEnumAsKey source = new ClassWithMapUsingEnumAsKey();
+		source.map = new HashMap<MappingMongoConverterUnitTests.FooBarEnum, String>();
+		source.map.put(FooBarEnum.FOO, "spring");
+		source.map.put(FooBarEnum.BAR, "data");
+
+		DBObject target = new BasicDBObject();
+		converter.write(source, target);
+
+		DBObject map = DBObjectTestUtils.getAsDBObject(target, "map");
+
+		assertThat(map.containsField("foo-enum-value"), is(true));
+		assertThat(map.containsField("bar-enum-value"), is(true));
+	}
+
+	/**
+	 * @see DATAMONGO-1118
+	 */
+	@Test
+	public void readsMapKeyUsingCustomConverter() {
+
+		MappingMongoConverter converter = new MappingMongoConverter(resolver, mappingContext);
+		converter.setCustomConversions(new CustomConversions(Arrays.asList(new StringToFooNumConverter())));
+		converter.afterPropertiesSet();
+
+		DBObject source = new BasicDBObject("map", new BasicDBObject("foo-enum-value", "spring"));
+
+		ClassWithMapUsingEnumAsKey target = converter.read(ClassWithMapUsingEnumAsKey.class, source);
+
+		assertThat(target.map.get(FooBarEnum.FOO), is("spring"));
+	}
+
 	static class GenericType<T> {
 		T content;
 	}
@@ -2303,4 +2369,50 @@ public class MappingMongoConverterUnitTests {
 		Optional<String> string = Optional.empty();
 		Optional<LocalDateTime> localDateTime = Optional.empty();
 	}
+
+	static enum FooBarEnum {
+		FOO, BAR;
+	}
+
+	static class ClassWithMapUsingEnumAsKey {
+		Map<FooBarEnum, String> map;
+	}
+
+	@WritingConverter
+	static class FooBarEnumToStringConverter implements Converter<FooBarEnum, String> {
+
+		@Override
+		public String convert(FooBarEnum source) {
+			if (source == null) {
+				return null;
+			}
+
+			return FooBarEnum.FOO.equals(source) ? "foo-enum-value" : "bar-enum-value";
+		}
+
+	}
+
+	@ReadingConverter
+	static class StringToFooNumConverter implements Converter<String, FooBarEnum> {
+
+		@Override
+		public FooBarEnum convert(String source) {
+
+			if (source == null) {
+				return null;
+			}
+
+			if (source.equals("foo-enum-value")) {
+				return FooBarEnum.FOO;
+			}
+			if (source.equals("bar-enum-value")) {
+				return FooBarEnum.BAR;
+			}
+
+			throw new ConversionNotSupportedException(source, String.class, null);
+		}
+
+	}
+
+
 }