Add Optional<JsonNode> JsonNode.asOptional() convenience method for #4867 (#4872)

Author: JooHyukKim

release-notes/VERSION-2.x

@@ -36,6 +36,8 @@ Project: jackson-databind
  (reported by Kornel Zemla)
 #4863: Add basic Stream support in `JsonNode`: `valueStream()`, `propertyStream()`,
   `forEachEntry()`
+#4867: Add `Optional<JsonNode> JsonNode.asOptional()` convenience method
+ (fix by Joo-Hyuk K)
 
 2.18.3 (not yet released)
 

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

@@ -759,6 +759,17 @@ public boolean asBoolean(boolean defaultValue) {
         return defaultValue;
     }
 
+    /**
+     * Method that will return a {@link JsonNode} wrapped in Java's {@link Optional}.
+     *
+     * @return `Optional<JsonNode>` containing this node, or {@link Optional#empty()}
+     *        if this is a {@link MissingNode}.
+     * @since 2.19
+     */
+    public Optional<JsonNode> asOptional() {
+        return Optional.of(this);
+    }
+
     /*
     /**********************************************************************
     /* Public API, extended traversal (2.10) with "required()"

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

@@ -1,6 +1,7 @@
 package com.fasterxml.jackson.databind.node;
 
 import java.io.IOException;
+import java.util.Optional;
 
 import com.fasterxml.jackson.core.*;
 import com.fasterxml.jackson.databind.JsonNode;
@@ -71,6 +72,11 @@ public JsonNodeType getNodeType()
     public boolean asBoolean(boolean defaultValue);
     */
 
+    @Override
+    public Optional<JsonNode> asOptional() {
+        return Optional.empty();
+    }
+
     /*
     /**********************************************************
     /* Serialization: bit tricky as we don't really have a value

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

@@ -1,6 +1,7 @@
 package com.fasterxml.jackson.databind.node;
 
 import java.util.Comparator;
+import java.util.Optional;
 
 import org.junit.jupiter.api.Test;
 
@@ -215,4 +216,37 @@ public void testArrayWithDefaultTyping() throws Exception
         assertEquals(1, obj.size());
         assertEquals(2, obj.path("a").asInt());
     }
+
+    // [databind#4867]
+    @Test
+    public void testAsOptional() {
+        // Test with MissingNode
+        JsonNode missingNode = MissingNode.getInstance();
+        Optional<JsonNode> missingOptional = missingNode.asOptional();
+        assertFalse(missingOptional.isPresent());
+
+        // Test with ObjectNode
+        ObjectNode objectNode = MAPPER.createObjectNode();
+        Optional<JsonNode> objectOptional = objectNode.asOptional();
+        assertTrue(objectOptional.isPresent());
+        assertEquals(objectNode, objectOptional.get());
+
+        // Test with ArrayNode
+        ArrayNode arrayNode = MAPPER.createArrayNode();
+        Optional<JsonNode> arrayOptional = arrayNode.asOptional();
+        assertTrue(arrayOptional.isPresent());
+        assertEquals(arrayNode, arrayOptional.get());
+
+        // Test with TextNode
+        TextNode textNode = TextNode.valueOf("text");
+        Optional<JsonNode> textOptional = textNode.asOptional();
+        assertTrue(textOptional.isPresent());
+        assertEquals(textNode, textOptional.get());
+
+        // Test with NullNode
+        NullNode nullNode = NullNode.getInstance();
+        Optional<JsonNode> nullOptional = nullNode.asOptional();
+        assertTrue(nullOptional.isPresent());
+        assertEquals(nullNode, nullOptional.get());
+    }
 }

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

@@ -62,6 +62,7 @@ public void testMissingViaMapper() throws Exception
         assertTrue(onode.isObject());
         assertEquals(0, onode.size());
         assertFalse(onode.isMissingNode()); // real node
+        assertTrue(onode.asOptional().isPresent());
         assertNull(onode.textValue());
 
         // how about dereferencing?
@@ -74,6 +75,7 @@ public void testMissingViaMapper() throws Exception
         JsonNode dummyNode2 = dummyNode.path(98);
         assertNotNull(dummyNode2);
         assertTrue(dummyNode2.isMissingNode());
+        assertFalse(dummyNode2.asOptional().isPresent());
         JsonNode dummyNode3 = dummyNode.path("field");
         assertNotNull(dummyNode3);
         assertTrue(dummyNode3.isMissingNode());
@@ -92,6 +94,7 @@ public void testMissingViaMapper() throws Exception
         assertTrue(dummyNode.isMissingNode());
         assertNull(dummyNode.get(0));
         assertNull(dummyNode.get("myfield"));
+        assertFalse(dummyNode.asOptional().isPresent());
         dummyNode2 = dummyNode.path(98);
         assertNotNull(dummyNode2);
         assertTrue(dummyNode2.isMissingNode());