Fixes #714: no more trailing tokens after root null (#752)

Author: cowtowncoder

release-notes/VERSION-2.x

@@ -6,6 +6,8 @@ Project: jackson-dataformat-xml
 
 #508: `XmlMapper` is unable to deserialise into an empty record
  (reported by @protazy)
+#714: Root-level `null` handling (via `xsi:nil`) leaves trailing token in
+ `JsonParser`-exposed token stream
 #745: Add feature to include `standalone='yes'` in xml declaration
  (contributed by @duoduobingbing)
 

src/main/java/com/fasterxml/jackson/dataformat/xml/deser/FromXmlParser.java

@@ -253,7 +253,7 @@ private Feature(boolean defaultState) {
      */
 
     /**
-     * Bitfield that indicates which numeric representations
+     * Bit field that indicates which numeric representations
      * have been calculated for the current type
      */
     protected int _numTypesValid = NR_UNKNOWN;
@@ -297,6 +297,8 @@ public FromXmlParser(IOContext ctxt, int genericParserFeatures, int xmlFeatures,
         //    changed in 2.10.2
         if (_xmlTokens.hasXsiNil()) {
             _nextToken = JsonToken.VALUE_NULL;
+            // 21-Apr-2025, tatu: [dataformat-xml#714] Must "flush" the stream
+            _xmlTokens.markAsStreamEnd();
         } else {
             switch (firstToken) {
             case XmlTokenStream.XML_START_ELEMENT:
@@ -689,16 +691,16 @@ public JsonToken nextToken() throws IOException
     {
         JsonToken t = nextToken0();
         if (t != null) {
-            final String loc = (_parsingContext == null) ? "NULL" : String.valueOf(_parsingContext.pathAsPointer());
+            final String loc = (_parsingContext == null) ? "<null>" : "'"+String.valueOf(_parsingContext.pathAsPointer())+"'";
             switch (t) {
             case FIELD_NAME:
-                System.out.printf("FromXmlParser.nextToken() at '%s': JsonToken.FIELD_NAME '%s'\n", loc, _parsingContext.currentName());
+                System.out.printf("FromXmlParser.nextToken() at %s: JsonToken.FIELD_NAME '%s'\n", loc, _parsingContext.getCurrentName());
                 break;
             case VALUE_STRING:
-                System.out.printf("FromXmlParser.nextToken() at '%s': JsonToken.VALUE_STRING '%s'\n", loc, getText());
+                System.out.printf("FromXmlParser.nextToken() at %s: JsonToken.VALUE_STRING '%s'\n", loc, getText());
                 break;
             default:
-                System.out.printf("FromXmlParser.nextToken() at '%s': %s\n", loc, t);
+                System.out.printf("FromXmlParser.nextToken() at %s: %s\n", loc, t);
             }
         }
         return t;

src/main/java/com/fasterxml/jackson/dataformat/xml/deser/XmlTokenStream.java

@@ -269,9 +269,6 @@ public int next() throws XMLStreamException
         case XML_START_ELEMENT: 
             System.out.printf(" XmlTokenStream.next(): XML_START_ELEMENT '%s' %s\n", _localName, _loc());
             break;
-        case XML_DELAYED_START_ELEMENT: 
-            System.out.printf(" XmlTokenStream.next(): XML_DELAYED_START_ELEMENT '%s' %s\n", _localName, _loc());
-            break;
         case XML_END_ELEMENT: 
             // 24-May-2020, tatu: no name available for end element so do not print
             System.out.printf(" XmlTokenStream.next(): XML_END_ELEMENT %s\n", _loc());
@@ -406,6 +403,16 @@ protected void pushbackCurrentToken()
         _repeatCurrentToken = true;
     }
 
+    /**
+     * Method that can be called to mark stream as having reached end of stream.
+     *
+     * @since 2.19
+     */
+    protected void markAsStreamEnd()
+    {
+        _currentState = XML_END;
+    }
+
     /**
      * Method called to skip any attributes current START_ELEMENT may have,
      * so that they are not returned as token.
@@ -460,6 +467,7 @@ private final int _next() throws XMLStreamException
                 // 08-Jul-2021, tatu: as per [dataformat-xml#467] just skip anything
                 //   element might have, no need to ensure it was empty
                 _xmlReader.skipElement();
+//System.out.println(" XmlTokenStream._next(): Got xsi:nil, skipping element");
                 return _handleEndElement();
             }
             if (_nextAttributeIndex < _attributeCount) {
@@ -693,7 +701,7 @@ private final void _checkXsiAttributes() {
         int count = _xmlReader.getAttributeCount();
         _attributeCount = count;
 
-        // [dataformat-xml#354]: xsi:nul handling; at first only if first attribute
+        // [dataformat-xml#354]: xsi:nil handling; at first only if first attribute
         if (count >= 1) {
             // [dataformat-xml#468]: may disable xsi:nil processing
             if (_cfgProcessXsiNil
@@ -703,6 +711,7 @@ private final void _checkXsiAttributes() {
                     _nextAttributeIndex = 1;
                     // but only mark as nil marker if enabled
                     _xsiNilFound = "true".equals(_xmlReader.getAttributeValue(0));
+//System.out.println(" XMLTokenStream._checkXsiAttributes(), _xsiNilFound: "+_xsiNilFound);
                     return;
                 }
             }
@@ -813,6 +822,8 @@ private final int _handleEndElement()
 
             }
         } else {
+//System.out.println(" XMLTokenStream._handleEndElement(): no wrapper");
+
             // Not (necessarily) known, as per above, so:
             _localName = "";
             _namespaceURI = "";

src/test/java/com/fasterxml/jackson/dataformat/xml/tofix/XsiNilBasic714Test.java

@@ -8,7 +8,6 @@
 import com.fasterxml.jackson.dataformat.xml.XmlMapper;
 import com.fasterxml.jackson.dataformat.xml.XmlTestUtil;
 import com.fasterxml.jackson.dataformat.xml.deser.FromXmlParser;
-import com.fasterxml.jackson.dataformat.xml.testutil.failure.JacksonTestFailureExpected;
 
 import static org.junit.jupiter.api.Assertions.*;
 
@@ -22,7 +21,6 @@ public class XsiNilBasic714Test extends XmlTestUtil
             .build();
 
     // [dataformat-xml#714]: trailing END_OBJECT
-    @JacksonTestFailureExpected
     @Test
     public void testRootPojoAsNull() throws Exception
     {
@@ -35,7 +33,6 @@ public void testRootPojoAsNull() throws Exception
     // [dataformat-xml#468]: Allow disabling xsi:nil special handling
 
     // [dataformat-xml#714]: trailing END_OBJECT
-    @JacksonTestFailureExpected
     @Test
     public void testDisableXsiNilRootProcessing() throws Exception
     {
@@ -46,10 +43,12 @@ public void testDisableXsiNilRootProcessing() throws Exception
         assertEquals("null", r.readValue(DOC).toString());
 
         // 07-Jul-2021, tatu: Alas! 2.x sets format feature flags too late to
-        //   affect root element (3.0 works correctly). So cannot test
-
-        ObjectReader noXsiNilReader = r.without(FromXmlParser.Feature.PROCESS_XSI_NIL);
+        //   affect root element (3.0 works correctly). Need a new mapper
+        XmlMapper mapper2 = mapperBuilder()
+                .enable(DeserializationFeature.FAIL_ON_TRAILING_TOKENS)
+                .disable(FromXmlParser.Feature.PROCESS_XSI_NIL)
+                .build();
         assertEquals(a2q("{'nil':'true'}"),
-                noXsiNilReader.readValue(DOC).toString());
+                mapper2.readerFor(JsonNode.class).readValue(DOC).toString());
     }
 }