Fix #4095: add JsonNode.withObjectProperty()/.withArrayProperty()

Author: cowtowncoder

release-notes/VERSION-2.x

@@ -72,6 +72,7 @@ Project: jackson-databind
   trying to setAccessible on `OptionalInt` with JDK 17+
 #4090: Support sequenced collections (JDK 21)S
  (contributed by @pjfanning)
+#4095: Add `withObjectProperty(String)`, `withArrayProperty(String)` in `JsonNode`
 #4122: Do not resolve wildcards if upper bound is too non-specific
  (contributed by @yawkat)
 

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

@@ -1261,6 +1261,36 @@ public ObjectNode withObject(JsonPointer ptr,
                 +getClass().getName()+"`");
     }
 
+    /**
+     * Method similar to {@link #withObject(JsonPointer, OverwriteMode, boolean)} -- basically
+     * short-cut to:
+     *<pre>
+     *   withObject(JsonPointer.compile("/"+propName), OverwriteMode.NULLS, false);
+     *</pre>
+     * that is, only matches immediate property on {@link ObjectNode}
+     * and will either use an existing {@link ObjectNode} that is
+     * value of the property, or create one if no value or value is {@code NullNode}.
+     * <br>
+     * Will fail with an exception if:
+     * <ul>
+     *  <li>Node method called on is NOT {@link ObjectNode}
+     *   </li>
+     *  <li>Property has an existing value that is NOT {@code NullNode} (explicit {@code null})
+     *   </li>
+     * </ul>
+     *
+     * @param propName Name of property that has or will have {@link ObjectNode} as value
+     *
+     * @return {@link ObjectNode} value of given property (existing or created)
+     *
+     * @since 2.16
+     */
+    public ObjectNode withObjectProperty(String propName) {
+        // To avoid abstract method, base implementation just fails
+        throw new UnsupportedOperationException("`JsonNode` not of type `ObjectNode` (but `"
+                +getClass().getName()+")`, cannot call `withObjectProperty(String)` on it");
+    }
+
     /**
      * Method that works in one of possible ways, depending on whether
      * {@code exprOrProperty} is a valid {@link JsonPointer} expression or
@@ -1409,6 +1439,36 @@ public ArrayNode withArray(JsonPointer ptr,
                 +getClass().getName());
     }
 
+    /**
+     * Method similar to {@link #withArray(JsonPointer, OverwriteMode, boolean)} -- basically
+     * short-cut to:
+     *<pre>
+     *   withArray(JsonPointer.compile("/"+propName), OverwriteMode.NULLS, false);
+     *</pre>
+     * that is, only matches immediate property on {@link ObjectNode}
+     * and will either use an existing {@link ArrayNode} that is
+     * value of the property, or create one if no value or value is {@code NullNode}.
+     * <br>
+     * Will fail with an exception if:
+     * <ul>
+     *  <li>Node method called on is NOT {@link ObjectNode}
+     *   </li>
+     *  <li>Property has an existing value that is NOT {@code NullNode} (explicit {@code null})
+     *   </li>
+     * </ul>
+     *
+     * @param propName Name of property that has or will have {@link ArrayNode} as value
+     *
+     * @return {@link ArrayNode} value of given property (existing or created)
+     *
+     * @since 2.16
+     */
+    public ArrayNode withArrayProperty(String propName) {
+        // To avoid abstract method, base implementation just fails
+        throw new UnsupportedOperationException("`JsonNode` not of type `ObjectNode` (but `"
+                +getClass().getName()+")`, cannot call `withArrayProperty(String)` on it");
+    }
+    
     /*
     /**********************************************************
     /* Public API, comparison

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

@@ -183,7 +183,7 @@ protected boolean _withXxxMayReplace(JsonNode node, OverwriteMode overwriteMode)
     public ArrayNode withArray(JsonPointer ptr,
             OverwriteMode overwriteMode, boolean preferIndex)
     {
-        // Degenerate case of using with "empty" path; ok if ObjectNode
+        // Degenerate case of using with "empty" path; ok if ArrayNode
         if (ptr.matches()) {
             if (this instanceof ArrayNode) {
                 return (ArrayNode) this;

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

@@ -89,6 +89,20 @@ public ObjectNode with(String exprOrProperty) {
         return result;
     }
 
+    @Override
+    public ObjectNode withObjectProperty(String propName) {
+        JsonNode child = _children.get(propName);
+        if (child == null || child.isNull()) {
+            return putObject(propName);
+        }
+        if (child.isObject()) {
+            return (ObjectNode) child;
+        }
+        return _reportWrongNodeType(
+"Cannot replace `JsonNode` of type `%s` with `ObjectNode` for property \"%s\" (default mode `OverwriteMode.%s`)",
+child.getClass().getName(), propName, OverwriteMode.NULLS);
+    }
+
     @SuppressWarnings("unchecked")
     @Override
     public ArrayNode withArray(String exprOrProperty)
@@ -111,6 +125,20 @@ public ArrayNode withArray(String exprOrProperty)
         return result;
     }
 
+    @Override
+    public ArrayNode withArrayProperty(String propName) {
+        JsonNode child = _children.get(propName);
+        if (child == null || child.isNull()) {
+            return putArray(propName);
+        }
+        if (child.isArray()) {
+            return (ArrayNode) child;
+        }
+        return _reportWrongNodeType(
+"Cannot replace `JsonNode` of type `%s` with `ArrayNode` for property \"%s\" with (default mode `OverwriteMode.%s`)",
+child.getClass().getName(), propName, OverwriteMode.NULLS);
+    }
+
     @Override
     protected ObjectNode _withObject(JsonPointer origPtr,
             JsonPointer currentPtr,

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

@@ -196,6 +196,47 @@ private void _verifyObjectReplaceFail(JsonNode doc, JsonPointer ptr, OverwriteMo
         }
     }
 
+    /*
+    /**********************************************************************
+    /* Test methods, withObjectProperty()
+    /**********************************************************************
+     */
+
+    public void testWithObjectProperty() throws Exception
+    {
+        ObjectNode root = MAPPER.createObjectNode();
+
+        // First: create new property value
+        ObjectNode match = root.withObjectProperty("a");
+        assertTrue(match.isObject());
+        assertEquals(a2q("{}"), match.toString());
+        match.put("value", 42);
+        assertEquals(a2q("{'a':{'value':42}}"), root.toString());
+
+        // Second: match existing Object property
+        ObjectNode match2 = root.withObjectProperty("a");
+        assertSame(match, match2);
+        match.put("value2", true);
+
+        assertEquals(a2q("{'a':{'value':42,'value2':true}}"),
+                root.toString());
+
+        // Third: match and overwrite existing null node
+        JsonNode root2 = MAPPER.readTree("{\"b\": null}");
+        ObjectNode match3 = root2.withObjectProperty("b");
+        assertNotSame(match, match3);
+        assertEquals("{\"b\":{}}", root2.toString());
+        
+        // and then failing case
+        JsonNode root3 = MAPPER.readTree("{\"c\": 123}");
+        try {
+            root3.withObjectProperty("c");
+            fail("Should not pass");
+        } catch (UnsupportedOperationException e) {
+            verifyException(e, "Cannot replace `JsonNode` of type ");
+        }
+    }
+
     /*
     /**********************************************************************
     /* Test methods, withArray()
@@ -315,4 +356,44 @@ public void testWithArray3882() throws Exception
         assertEquals(a2q("{'key1':{'array1':[{'element1':['v1']}]}}"),
                 root.toString());
     }
+
+    /*
+    /**********************************************************************
+    /* Test methods, withArrayProperty()
+    /**********************************************************************
+     */
+
+    public void testWithArrayProperty() throws Exception
+    {
+        ObjectNode root = MAPPER.createObjectNode();
+
+        // First: create new property value
+        ArrayNode match = root.withArrayProperty("a");
+        assertTrue(match.isArray());
+        assertEquals(a2q("[]"), match.toString());
+        match.add(42);
+        assertEquals(a2q("{'a':[42]}"), root.toString());
+
+        // Second: match existing Object property
+        ArrayNode match2 = root.withArrayProperty("a");
+        assertSame(match, match2);
+        match.add(true);
+
+        assertEquals(a2q("{'a':[42,true]}"), root.toString());
+
+        // Third: match and overwrite existing null node
+        JsonNode root2 = MAPPER.readTree("{\"b\": null}");
+        ArrayNode match3 = root2.withArrayProperty("b");
+        assertNotSame(match, match3);
+        assertEquals("{\"b\":[]}", root2.toString());
+        
+        // and then failing case
+        JsonNode root3 = MAPPER.readTree("{\"c\": 123}");
+        try {
+            root3.withArrayProperty("c");
+            fail("Should not pass");
+        } catch (UnsupportedOperationException e) {
+            verifyException(e, "Cannot replace `JsonNode` of type ");
+        }
+    }
 }