SLING-9774 The ValueMapUtil#merge behavior is different from the
deprecated CompositeValueMap
diff --git a/src/main/java/org/apache/sling/api/wrappers/impl/MergingValueMap.java b/src/main/java/org/apache/sling/api/wrappers/impl/MergingValueMap.java
index 9e2bef3..6cd2e5f 100644
--- a/src/main/java/org/apache/sling/api/wrappers/impl/MergingValueMap.java
+++ b/src/main/java/org/apache/sling/api/wrappers/impl/MergingValueMap.java
@@ -18,10 +18,6 @@
*/
package org.apache.sling.api.wrappers.impl;
-import org.apache.sling.api.resource.ValueMap;
-import org.apache.sling.api.wrappers.ValueMapUtil;
-import org.jetbrains.annotations.NotNull;
-
import java.util.AbstractMap;
import java.util.ArrayList;
import java.util.Collection;
@@ -29,10 +25,15 @@
import java.util.List;
import java.util.Map;
import java.util.Objects;
+import java.util.Optional;
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.Stream;
+import org.apache.sling.api.resource.ValueMap;
+import org.apache.sling.api.wrappers.ValueMapUtil;
+import org.jetbrains.annotations.NotNull;
+
/**
* Merge provided {@code ValueMaps} into a single view {@code ValueMap} that aggregates
* all key-value pairs of the given maps. The value for a key-value pair is taken from
@@ -108,12 +109,42 @@
@Override
public Object get(Object key) {
return valueMaps.stream()
- .map(vm -> vm.get(key))
+ .map(vm -> getOrEmpty(vm, key)) // SLING-9774
.filter(Objects::nonNull)
.findFirst()
+ .filter(Optional::isPresent) // skip if Optional#empty
+ .map(Optional::get) // dig the value out of the Optional
.orElse(null);
}
+ /**
+ * SLING-9774 - Returns an {@code Optional} describing the value in the map value for
+ * the supplied key. Special handling is supplied for an existing key that
+ * resolves to a null value.
+ *
+ * @param vm the map to get the value from
+ * @param key the key to get the value for
+ * @return an {@code Optional} with a present value if the specified value
+ * is non-null, otherwise if the map contains the key then an empty {@code Optional},
+ * otherwise null
+ */
+ private Optional<Object> getOrEmpty(ValueMap vm, Object key) {
+ Optional<Object> opt = null;
+ Object value = vm.get(key);
+ if (value == null) {
+ // check if the null value is for a real entry
+ if (vm.containsKey(key)) {
+ // key exists so return the empty Optional
+ // instead of null
+ opt = Optional.empty();
+ }
+ } else {
+ // not null so just wrap the value
+ opt = Optional.of(value);
+ }
+ return opt;
+ }
+
@NotNull
@Override
public Set<String> keySet() {
diff --git a/src/test/java/org/apache/sling/api/resource/impl/ValueMapUtilMergeTest.java b/src/test/java/org/apache/sling/api/resource/impl/ValueMapUtilMergeTest.java
index 470955a..c107cdb 100644
--- a/src/test/java/org/apache/sling/api/resource/impl/ValueMapUtilMergeTest.java
+++ b/src/test/java/org/apache/sling/api/resource/impl/ValueMapUtilMergeTest.java
@@ -157,6 +157,25 @@
typicalVM().clear();
}
+ /**
+ * SLING-9774 - Test that a key=null value in the first map is used
+ * instead of the key=value entry in the second map
+ */
+ @Test
+ public void testNullValueForExistingKey() {
+ // value is null in the first map
+ ValueMap v1 = createValueMap("k1", null);
+
+ // value is not null in the second map
+ ValueMap v2 = createValueMap("k1", "11");
+
+ // expected to get null value since the first
+ // map had a real key
+ ValueMap merge = merge(v1, v2);
+ assertTrue(merge.containsKey("k1"));
+ assertNull(merge.get("k1"));
+ }
+
private static ValueMap createValueMap(Object... pairs) {
ValueMap vm = new ValueMapDecorator(new HashMap<>());
for (int i = 0; i < pairs.length; i += 2) {
