Fixed #237

FasterXML · Jun 6, 2013 · 3955abb · 3955abb
1 parent df7fb3d
commit 3955abb
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diff --git a/release-notes/VERSION b/release-notes/VERSION
@@ -3,6 +3,9 @@ Version: 2.3.0 (xx-xxx-2013)
 
 New minor version.
 
+#237: Add `DeserializationFeature.FAIL_ON_READING_DUP_TREE_KEY` to optionally
+  throw `JsonMappingException` on duplicate keys, tree model (`JsonNode`)
+
 ------------------------------------------------------------------------
 === History: ===
 ------------------------------------------------------------------------

diff --git a/src/main/java/com/fasterxml/jackson/databind/DeserializationFeature.java b/src/main/java/com/fasterxml/jackson/databind/DeserializationFeature.java
@@ -139,6 +139,21 @@ public enum DeserializationFeature implements ConfigFeature
      * @since 2.2
      */
     FAIL_ON_INVALID_SUBTYPE(true),
+
+    /**
+     * Feature that determines what happens when reading JSON content into tree
+     * ({@link com.fasterxml.jackson.core.TreeNode}) and a duplicate key
+     * is encountered (property name that was already seen for the JSON Object).
+     * If enabled, {@link JsonMappingException} will be thrown; if disabled, no exception
+     * is thrown and the new (later) value overwrites the earlier value.
+     *<p>
+     * Note that this property does NOT affect other aspects of data-binding; that is,
+     * no detection is done with respect to POJO properties or {@link java.util.Map}
+     * keys. New features may be added to control additional cases.
+     * 
+     * @since 2.3
+     */
+    FAIL_ON_READING_DUP_TREE_KEY(false),
 
     /**
      * Feature that determines whether Jackson code should catch

diff --git a/src/main/java/com/fasterxml/jackson/databind/deser/std/JsonNodeDeserializer.java b/src/main/java/com/fasterxml/jackson/databind/deser/std/JsonNodeDeserializer.java
@@ -160,6 +160,19 @@ protected void _reportProblem(JsonParser jp, String msg)
         throw new JsonMappingException(msg, jp.getTokenLocation());
     }
 
+    /**
+     * 
+     * @deprecated Since 2.3, use the overloaded variant
+     */
+    @Deprecated
+    protected void _handleDuplicateField(String fieldName, ObjectNode objectNode,
+                                         JsonNode oldValue, JsonNode newValue)
+        throws JsonProcessingException
+    {
+        // By default, we don't do anything
+        ;
+    }
+
     /**
      * Method called when there is a duplicate value for a field.
      * By default we don't care, and the last value is used.
@@ -173,12 +186,18 @@ protected void _reportProblem(JsonParser jp, String msg)
      *   was added
      * @param newValue Newly added value just added to the object node
      */
-    protected void _handleDuplicateField(String fieldName, ObjectNode objectNode,
-                                         JsonNode oldValue, JsonNode newValue)
+    protected void _handleDuplicateField(JsonParser jp, DeserializationContext ctxt,
+            JsonNodeFactory nodeFactory,
+            String fieldName, ObjectNode objectNode,
+            JsonNode oldValue, JsonNode newValue)
         throws JsonProcessingException
     {
-        // By default, we don't do anything
-        ;
+        // [Issue#237]: Report an error if asked to do so:
+        if (ctxt.isEnabled(DeserializationFeature.FAIL_ON_READING_DUP_TREE_KEY)) {
+            _reportProblem(jp, "Duplicate field '"+fieldName+"' for ObjectNode: not allowed when FAIL_ON_READING_DUP_TREE_KEY enabled");
+        }
+        // Backwards-compatibility; call in case it's overloaded
+        _handleDuplicateField(fieldName, objectNode, oldValue, newValue);
     }
 
     /*
@@ -214,7 +233,8 @@ protected final ObjectNode deserializeObject(JsonParser jp, DeserializationConte
             }
             JsonNode old = node.replace(fieldName, value);
             if (old != null) {
-                _handleDuplicateField(fieldName, node, old, value);
+                _handleDuplicateField(jp, ctxt, nodeFactory,
+                        fieldName, node, old, value);
             }
         }
         return node;

diff --git a/src/test/java/com/fasterxml/jackson/databind/node/TestObjectNode.java b/src/test/java/com/fasterxml/jackson/databind/node/TestObjectNode.java
@@ -229,4 +229,24 @@ public void testSetAll() throws Exception
         assertEquals(3, root3.size());
         assertEquals(1, root3.path("a").intValue());
     }
+
+    // [Issue#237] (databind): support DeserializationFeature#FAIL_ON_READING_DUP_TREE_KEY
+    public void testFailOnDupKeys() throws Exception
+    {
+        final String DUP_JSON = "{ \"a\":1, \"a\":2 }";
+
+        // first: verify defaults:
+        ObjectMapper mapper = new ObjectMapper();
+        assertFalse(mapper.isEnabled(DeserializationFeature.FAIL_ON_READING_DUP_TREE_KEY));
+        ObjectNode root = (ObjectNode) mapper.readTree(DUP_JSON);
+        assertEquals(2, root.path("a").asInt());
+
+        // and then enable checks:
+        try {
+            mapper.reader(DeserializationFeature.FAIL_ON_READING_DUP_TREE_KEY).readTree(DUP_JSON);
+            fail("Should have thrown exception!");
+        } catch (JsonMappingException e) {
+            verifyException(e, "duplicate field 'a'");
+        }
+    }
 }