Fix #3809: Add ObjectNode.properties()

release-notes/VERSION-2.x

@@ -61,6 +61,8 @@ Project: jackson-databind
  (reported by Christoph S)
 #3796: Enum Deserialisation Failing with Polymorphic type validator
  (reported by @sagarika4)
+#3809: Add Stream-friendly alternative to `ObjectNode.fields()`:
+  `Set<Map.Entry<String, JsonNode>> properties()`
 #3816: TokenBuffer does not implement writeString(Reader reader, int len)
  (reported by Patrick S)
 #3819: Add convenience method `SimpleBeanPropertyFilter.filterOutAll()` as

src/main/java/com/fasterxml/jackson/databind/JsonNode.java

@@ -1017,6 +1017,21 @@ public Iterator<Map.Entry<String, JsonNode>> fields() {
         return ClassUtil.emptyIterator();
     }
 
+    /**
+     * Accessor that will return properties of {@code ObjectNode}
+     * similar to how {@link Map#entrySet()} works; 
+     * for other node types will return empty {@link java.util.Set}.
+     *
+     * @return Set of properties, if this node is an {@code ObjectNode}
+     * ({@link JsonNode#isObject()} returns {@code true}); empty
+     * {@link java.util.Set} otherwise.
+     *
+     * @since 2.15
+     */
+    public Set<Map.Entry<String, JsonNode>> properties() {
+        return Collections.emptySet();
+    }
+
     /*
     /**********************************************************
     /* Public API, find methods

src/main/java/com/fasterxml/jackson/databind/node/ObjectNode.java

@@ -283,6 +283,17 @@ public Iterator<Map.Entry<String, JsonNode>> fields() {
         return _children.entrySet().iterator();
     }
 
+    /**
+     * Method to use for accessing all properties (with both names
+     * and values) of this JSON Object.
+     *
+     * @since 2.15
+     */
+    @Override
+    public Set<Map.Entry<String, JsonNode>> properties() {
+        return _children.entrySet();
+    }
+
     @Override
     public boolean equals(Comparator<JsonNode> comparator, JsonNode o)
     {

src/test/java/com/fasterxml/jackson/databind/node/ObjectNodeTest.java

@@ -3,6 +3,7 @@
 import java.math.BigDecimal;
 import java.math.BigInteger;
 import java.util.*;
+import java.util.stream.Collectors;
 
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonInclude;
@@ -32,13 +33,6 @@ public DataImpl(JsonNode n) {
 
         @JsonValue
         public JsonNode value() { return root; }
-
-        /*
-        public Wrapper(ObjectNode n) { root = n; }
-
-        @JsonValue
-        public ObjectNode value() { return root; }
-        */
     }
 
     static class ObNodeWrapper {
@@ -69,7 +63,7 @@ static class MyValue
     /**********************************************************
      */
 
-    private final ObjectMapper MAPPER = sharedMapper();
+    private final ObjectMapper MAPPER = newJsonMapper();
 
     public void testSimpleObject() throws Exception
     {
@@ -509,12 +503,30 @@ public void testIssue941() throws Exception
 
     public void testSimpleMismatch() throws Exception
     {
-        ObjectMapper mapper = objectMapper();
         try {
-            mapper.readValue("[ 1, 2, 3 ]", ObjectNode.class);
+            MAPPER.readValue("[ 1, 2, 3 ]", ObjectNode.class);
             fail("Should not pass");
         } catch (MismatchedInputException e) {
             verifyException(e, "from Array value (token `JsonToken.START_ARRAY`)");
         }
     }
+
+    // [databind#3809]
+    public void testPropertiesTraversal() throws Exception
+    {
+        // Nothing to traverse for other types
+        assertEquals("", _toString(MAPPER.createArrayNode()));
+        assertEquals("", _toString(MAPPER.getNodeFactory().textNode("foo")));
+
+        // But yes for ObjectNode:
+        JsonNode n = MAPPER.readTree(a2q(
+                "{ 'a':1, 'b':true,'c':'stuff'}"));
+        assertEquals("a/1,b/true,c/\"stuff\"", _toString(n));
+    }
+
+    private String _toString(JsonNode n) {
+        return n.properties().stream()
+                .map(e -> e.getKey() + "/" + e.getValue())
+                .collect(Collectors.joining(","));
+    }
 }