Merge branch '131-flex-maps-support-null-entries' into 'dev'

Resolve "Flex maps: support null entries"

See merge request objectbox/objectbox-java!141

Author: greenrobot-team

objectbox-java/src/main/java/io/objectbox/converter/FlexObjectConverter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2021 ObjectBox Ltd. All rights reserved.
+ * Copyright 2021-2024 ObjectBox Ltd. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,10 +16,6 @@
 
 package io.objectbox.converter;
 
-import io.objectbox.flatbuffers.ArrayReadWriteBuf;
-import io.objectbox.flatbuffers.FlexBuffers;
-import io.objectbox.flatbuffers.FlexBuffersBuilder;
-
 import java.lang.reflect.Field;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
@@ -28,6 +24,10 @@
 import java.util.Map;
 import java.util.concurrent.atomic.AtomicReference;
 
+import io.objectbox.flatbuffers.ArrayReadWriteBuf;
+import io.objectbox.flatbuffers.FlexBuffers;
+import io.objectbox.flatbuffers.FlexBuffersBuilder;
+
 /**
  * Converts between {@link Object} properties and byte arrays using FlexBuffers.
  * <p>
@@ -126,12 +126,14 @@ private void addMap(FlexBuffersBuilder builder, String mapKey, Map<Object, Objec
         for (Map.Entry<Object, Object> entry : map.entrySet()) {
             Object rawKey = entry.getKey();
             Object value = entry.getValue();
-            if (rawKey == null || value == null) {
-                throw new IllegalArgumentException("Map keys or values must not be null");
+            if (rawKey == null) {
+                throw new IllegalArgumentException("Map keys must not be null");
             }
             checkMapKeyType(rawKey);
             String key = rawKey.toString();
-            if (value instanceof Map) {
+            if (value == null) {
+                builder.putNull(key);
+            } else if (value instanceof Map) {
                 //noinspection unchecked
                 addMap(builder, key, (Map<Object, Object>) value);
             } else if (value instanceof List) {
@@ -171,9 +173,8 @@ private void addVector(FlexBuffersBuilder builder, String vectorKey, List<Object
 
         for (Object item : list) {
             if (item == null) {
-                throw new IllegalArgumentException("List elements must not be null");
-            }
-            if (item instanceof Map) {
+                builder.putNull();
+            } else if (item instanceof Map) {
                 //noinspection unchecked
                 addMap(builder, null, (Map<Object, Object>) item);
             } else if (item instanceof List) {
@@ -213,7 +214,9 @@ public Object convertToEntityProperty(byte[] databaseValue) {
         if (databaseValue == null) return null;
 
         FlexBuffers.Reference value = FlexBuffers.getRoot(new ArrayReadWriteBuf(databaseValue, databaseValue.length));
-        if (value.isMap()) {
+        if (value.isNull()) {
+            return null;
+        } else if (value.isMap()) {
             return buildMap(value.asMap());
         } else if (value.isVector()) {
             return buildList(value.asVector());
@@ -277,7 +280,9 @@ private Map<Object, Object> buildMap(FlexBuffers.Map map) {
             String rawKey = keys.get(i).toString();
             Object key = convertToKey(rawKey);
             FlexBuffers.Reference value = values.get(i);
-            if (value.isMap()) {
+            if (value.isNull()) {
+                resultMap.put(key, null);
+            } else if (value.isMap()) {
                 resultMap.put(key, buildMap(value.asMap()));
             } else if (value.isVector()) {
                 resultMap.put(key, buildList(value.asVector()));
@@ -314,7 +319,9 @@ private List<Object> buildList(FlexBuffers.Vector vector) {
 
         for (int i = 0; i < itemCount; i++) {
             FlexBuffers.Reference item = vector.get(i);
-            if (item.isMap()) {
+            if (item.isNull()) {
+                list.add(null);
+            } else if (item.isMap()) {
                 list.add(buildMap(item.asMap()));
             } else if (item.isVector()) {
                 list.add(buildList(item.asVector()));

tests/objectbox-java-test/src/test/java/io/objectbox/converter/FlexMapConverterTest.java

@@ -1,14 +1,32 @@
+/*
+ * Copyright 2020-2024 ObjectBox Ltd. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package io.objectbox.converter;
 
 import org.junit.Test;
 
-import javax.annotation.Nullable;
 import java.time.Instant;
 import java.util.HashMap;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 
+import javax.annotation.Nullable;
+
+
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertThrows;
@@ -37,6 +55,7 @@ public void keysString_valsSupportedTypes_works() {
         map.put("long", 1L);
         map.put("float", 1.3f);
         map.put("double", -1.4d);
+        map.put("null", null);
         Map<String, Object> restoredMap = convertAndBack(map, converter);
         // Java integers are returned as Long if one value is larger than 32 bits, so expect Long.
         map.put("byte", 1L);
@@ -158,10 +177,12 @@ public void nestedMap_works() {
         Map<String, String> embeddedMap1 = new HashMap<>();
         embeddedMap1.put("Hello1", "Grüezi1");
         embeddedMap1.put("💡1", "Idea1");
+        embeddedMap1.put("null1", null);
         map.put("Hello", embeddedMap1);
         Map<String, String> embeddedMap2 = new HashMap<>();
         embeddedMap2.put("Hello2", "Grüezi2");
         embeddedMap2.put("💡2", "Idea2");
+        embeddedMap2.put("null2", null);
         map.put("💡", embeddedMap2);
         convertAndBackThenAssert(map, converter);
     }
@@ -181,6 +202,7 @@ public void nestedList_works() {
         embeddedList1.add(-2L);
         embeddedList1.add(1.3f);
         embeddedList1.add(-1.4d);
+        embeddedList1.add(null);
         map.put("Hello", embeddedList1);
         List<Object> embeddedList2 = new LinkedList<>();
         embeddedList2.add("Grüezi");
@@ -213,17 +235,12 @@ public void nestedListByteArray_works() {
     }
 
     @Test
-    public void nullKeyOrValue_throws() {
+    public void nullKey_throws() {
         FlexObjectConverter converter = new StringFlexMapConverter();
         Map<String, String> map = new HashMap<>();
 
-        map.put("Hello", null);
-        convertThenAssertThrows(map, converter, "Map keys or values must not be null");
-
-        map.clear();
-
         map.put(null, "Idea");
-        convertThenAssertThrows(map, converter, "Map keys or values must not be null");
+        convertThenAssertThrows(map, converter, "Map keys must not be null");
     }
 
     @Test

tests/objectbox-java-test/src/test/java/io/objectbox/converter/FlexObjectConverterTest.java

@@ -1,13 +1,30 @@
+/*
+ * Copyright 2021-2024 ObjectBox Ltd. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package io.objectbox.converter;
 
 import org.junit.Test;
 
-import javax.annotation.Nullable;
 import java.util.LinkedList;
 import java.util.List;
 
+import javax.annotation.Nullable;
+
+
 import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertThrows;
 
 /**
  * Tests {@link FlexObjectConverter} basic types and flexible list conversion.
@@ -55,6 +72,7 @@ public void list_works() {
         list.add(-2L);
         list.add(1.3f);
         list.add(-1.4d);
+        list.add(null);
         List<Object> restoredList = convertAndBack(list, converter);
         // Java integers are returned as Long as one element is larger than 32 bits, so expect Long.
         list.set(2, 1L);
@@ -63,14 +81,6 @@ public void list_works() {
         // Java Float is returned as Double, so expect Double.
         list.set(6, (double) 1.3f);
         assertEquals(list, restoredList);
-
-        // list with null element
-        list.add(null);
-        IllegalArgumentException exception = assertThrows(
-                IllegalArgumentException.class,
-                () -> convertAndBack(list, converter)
-        );
-        assertEquals("List elements must not be null", exception.getMessage());
     }
 
     @SuppressWarnings("unchecked")