Fix #3056

Author: cowtowncoder

release-notes/VERSION-2.x

@@ -14,6 +14,9 @@ Project: jackson-databind
  (fix contributed by Migwel@github)
 #3038: Two cases of incorrect error reporting about DeserializationFeature
  (reported by Jelle V)
+#3056: MismatchedInputException: Cannot deserialize instance of
+  `com.fasterxml.jackson.databind.node.ObjectNode` out of VALUE_NULL token
+ (reported by Stexxen@github)
 
 2.12.1 (08-Jan-2021)
 

src/main/java/com/fasterxml/jackson/databind/deser/std/JsonNodeDeserializer.java

@@ -389,18 +389,25 @@ protected final JsonNode updateObject(JsonParser p, DeserializationContext ctxt,
             JsonNode old = node.get(key);
             if (old != null) {
                 if (old instanceof ObjectNode) {
-                    JsonNode newValue = updateObject(p, ctxt, (ObjectNode) old);
-                    if (newValue != old) {
-                        node.set(key, newValue);
+                    // [databind#3056]: merging only if had Object and
+                    // getting an Object
+                    if (t == JsonToken.START_OBJECT) {
+                        JsonNode newValue = updateObject(p, ctxt, (ObjectNode) old);
+                        if (newValue != old) {
+                            node.set(key, newValue);
+                        }
+                        continue;
                     }
-                    continue;
-                }
-                if (old instanceof ArrayNode) {
-                    JsonNode newValue = updateArray(p, ctxt, (ArrayNode) old);
-                    if (newValue != old) {
-                        node.set(key, newValue);
+                } else if (old instanceof ArrayNode) {
+                    // [databind#3056]: related to Object handling, ensure
+                    // Array values also match for mergeability
+                    if (t == JsonToken.START_ARRAY) {
+                        JsonNode newValue = updateArray(p, ctxt, (ArrayNode) old);
+                        if (newValue != old) {
+                            node.set(key, newValue);
+                        }
+                        continue;
                     }
-                    continue;
                 }
             }
             if (t == null) { // can this ever occur?
@@ -436,10 +443,15 @@ protected final JsonNode updateObject(JsonParser p, DeserializationContext ctxt,
             default:
                 value = deserializeAny(p, ctxt, nodeFactory);
             }
+            // 15-Feb-2021, tatu: I don't think this should have been called
+            //   on update case (was until 2.12.2) and was simply result of
+            //   copy-paste.
+            /*
             if (old != null) {
                 _handleDuplicateField(p, ctxt, nodeFactory,
                         key, node, old, value);
             }
+            */
             node.set(key, value);
         }
         return node;
@@ -449,8 +461,9 @@ protected final ArrayNode deserializeArray(JsonParser p, DeserializationContext
             final JsonNodeFactory nodeFactory) throws IOException
     {
         ArrayNode node = nodeFactory.arrayNode();
-        while (true) {
-            JsonToken t = p.nextToken();
+        JsonToken t;
+
+        while ((t = p.nextToken()) != null) {
             switch (t.id()) {
             case JsonTokenId.ID_START_OBJECT:
                 node.add(deserializeObject(p, ctxt, nodeFactory));
@@ -483,6 +496,8 @@ protected final ArrayNode deserializeArray(JsonParser p, DeserializationContext
                 break;
             }
         }
+        // should never really get here
+        return node;
     }
 
     /**

src/test/java/com/fasterxml/jackson/databind/deser/merge/NodeMergeTest.java

@@ -11,6 +11,9 @@ public class NodeMergeTest extends BaseMapTest
     final static ObjectMapper MAPPER = jsonMapperBuilder()
             // 26-Oct-2016, tatu: Make sure we'll report merge problems by default
             .disable(MapperFeature.IGNORE_MERGE_FOR_UNMERGEABLE)
+            // 15-Feb-2021, tatu: slightly related to [databind#3056],
+            //   ensure that dup detection will not trip handling here
+            .enable(DeserializationFeature.FAIL_ON_READING_DUP_TREE_KEY)
             .build();
 
     static class ObjectNodeWrapper {
@@ -69,8 +72,8 @@ public void testObjectDeepUpdate() throws Exception
         base.putNull("misc");
         assertSame(base,
                 MAPPER.readerForUpdating(base)
-                .readValue(aposToQuotes(
-                        "{'props':{'value':true, 'extra':25.5, 'array' : [ 3 ]}}")));
+                .readValue(a2q(
+"{'props':{'value':true, 'extra':25.5, 'array' : [ 3 ]}}")));
         assertEquals(2, base.size());
         ObjectNode resultProps = (ObjectNode) base.get("props");
         assertEquals(4, resultProps.size());
@@ -114,4 +117,49 @@ public void testArrayNodeMerge() throws Exception
         assertEquals(0, n.size());
         assertEquals("foo", w.list.get(5).asText());
     }
+
+    // [databind#3056]
+    public void testUpdateObjectNodeWithNull() throws Exception
+    {
+        JsonNode src = MAPPER.readTree(a2q("{'test':{}}"));
+        JsonNode update = MAPPER.readTree(a2q("{'test':null}"));
+
+        ObjectNode result = MAPPER.readerForUpdating(src)
+            .readValue(update, ObjectNode.class);
+
+        assertEquals(a2q("{'test':null}"), result.toString());
+    }
+
+    public void testUpdateObjectNodeWithNumber() throws Exception
+    {
+        JsonNode src = MAPPER.readTree(a2q("{'test':{}}"));
+        JsonNode update = MAPPER.readTree(a2q("{'test':123}"));
+
+        ObjectNode result = MAPPER.readerForUpdating(src)
+            .readValue(update, ObjectNode.class);
+
+        assertEquals(a2q("{'test':123}"), result.toString());
+    }
+
+    public void testUpdateArrayWithNull() throws Exception
+    {
+        JsonNode src = MAPPER.readTree(a2q("{'test':[]}"));
+        JsonNode update = MAPPER.readTree(a2q("{'test':null}"));
+
+        ObjectNode result = MAPPER.readerForUpdating(src)
+            .readValue(update, ObjectNode.class);
+
+        assertEquals(a2q("{'test':null}"), result.toString());
+    }
+
+    public void testUpdateArrayWithString() throws Exception
+    {
+        JsonNode src = MAPPER.readTree(a2q("{'test':[]}"));
+        JsonNode update = MAPPER.readTree(a2q("{'test':'n/a'}"));
+
+        ObjectNode result = MAPPER.readerForUpdating(src)
+            .readValue(update, ObjectNode.class);
+
+        assertEquals(a2q("{'test':'n/a'}"), result.toString());
+    }
 }