#199 DefaultArangoConverter - handle nulls when writing Maps, Arrays and Collections (#200)

Author: nikita-i-turvo

src/main/java/com/arangodb/springframework/core/convert/DefaultArangoConverter.java

@@ -691,7 +691,10 @@ private void writeMap(
 			final Object key = entry.getKey();
 			final Object value = entry.getValue();
 
-			writeInternal(convertId(key), value, sink, getNonNullMapValueType(definedType));
+			String convertedKey = convertId(key);
+			if (value != null) {
+				writeInternal(convertedKey, value, sink, getNonNullMapValueType(definedType));
+			}
 		}
 
 		sink.close();
@@ -706,7 +709,11 @@ private void writeCollection(
 		sink.add(attribute, ValueType.ARRAY);
 
 		for (final Object entry : asCollection(source)) {
-			writeInternal(null, entry, sink, getNonNullComponentType(definedType));
+			if (entry == null) {
+				writeSimple(null, null, sink);
+			} else {
+				writeInternal(null, entry, sink, getNonNullComponentType(definedType));
+			}
 		}
 
 		sink.close();
@@ -726,7 +733,11 @@ private void writeArray(
 			sink.add(attribute, ValueType.ARRAY);
 			for (int i = 0; i < Array.getLength(source); ++i) {
 				final Object element = Array.get(source, i);
-				writeInternal(null, element, sink, getNonNullComponentType(definedType));
+				if (element == null) {
+					writeSimple(null, null, sink);
+				} else {
+					writeInternal(null, element, sink, getNonNullComponentType(definedType));
+				}
 			}
 			sink.close();
 		}

src/test/java/com/arangodb/springframework/core/mapping/GeneralMappingTest.java

@@ -49,6 +49,7 @@
 import java.util.*;
 
 import static org.hamcrest.Matchers.*;
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertThat;
 
 /**
@@ -589,4 +590,57 @@ public void readMapInMap() {
 		assertThat(find.isPresent(), is(true));
 		assertThat(find.get().value, is(map));
 	}
+
+	@Test
+	public void readMapInMapWithNull() {
+		final MapInMapTestEntity entity = new MapInMapTestEntity();
+		final Map<String, Object> map = new HashMap<>();
+		Map<String, Object> nested = new HashMap<>();
+		nested.put("key1", "test");
+		nested.put("key2", null);
+		map.put("nested", nested);
+		entity.value = map;
+		template.insert(entity);
+		final Optional<MapInMapTestEntity> find = template.find(entity.id, MapInMapTestEntity.class);
+		assertThat(find.isPresent(), is(true));
+		Map<String, Object> nestedResult = (Map<String, Object>) find.get().value.get("nested");
+		assertThat(nestedResult.size(), is(1));
+		assertThat(nestedResult.get("key1"), is("test"));
+	}
+
+	@Test
+	public void readMapInMapWithArray() {
+		final MapInMapTestEntity entity = new MapInMapTestEntity();
+		final Map<String, Object> map = new HashMap<>();
+		Map<String, Object> nested = new HashMap<>();
+		String[] nestedArray = {"test", null};
+		nested.put("key1", nestedArray);
+		map.put("nested", nested);
+		entity.value = map;
+		template.insert(entity);
+		final Optional<MapInMapTestEntity> find = template.find(entity.id, MapInMapTestEntity.class);
+		assertThat(find.isPresent(), is(true));
+		Map<String, Object> nestedResult = (Map<String, Object>) find.get().value.get("nested");
+		assertThat(nestedResult.size(), is(1));
+		assertThat(((List<String>) nestedResult.get("key1")).size(), is(2));
+		assertEquals(Arrays.asList(nestedArray), nestedResult.get("key1"));
+	}
+
+	@Test
+	public void readMapInMapWithCollection() {
+		final MapInMapTestEntity entity = new MapInMapTestEntity();
+		final Map<String, Object> map = new HashMap<>();
+		Map<String, Object> nested = new HashMap<>();
+		Collection<String> nestedCollection = Arrays.asList("test", null);
+		nested.put("key1", nestedCollection);
+		map.put("nested", nested);
+		entity.value = map;
+		template.insert(entity);
+		final Optional<MapInMapTestEntity> find = template.find(entity.id, MapInMapTestEntity.class);
+		assertThat(find.isPresent(), is(true));
+		Map<String, Object> nestedResult = (Map<String, Object>) find.get().value.get("nested");
+		assertThat(nestedResult.size(), is(1));
+		assertThat(((List<String>) nestedResult.get("key1")).size(), is(2));
+		assertEquals(nestedCollection, nestedResult.get("key1"));
+	}
 }