Fix #354 (support xsi:nil)

release-notes/VERSION-2.x

@@ -8,6 +8,7 @@ Project: jackson-dataformat-xml
 
 #242: Deserialization of class inheritance depends on attributes order
  (reported by Victor K)
+#354: Support mapping `xsi:nul` marked elements as `null`s (`JsonToken.VALUE_NULL`)
 
 2.10.0.pr2 (31-Aug-2019)
 

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

@@ -176,16 +176,25 @@ private Feature(boolean defaultState) {
 
     public FromXmlParser(IOContext ctxt, int genericParserFeatures, int xmlFeatures,
             ObjectCodec codec, XMLStreamReader xmlReader)
+        throws IOException
     {
         super(genericParserFeatures);
         _formatFeatures = xmlFeatures;
         _ioContext = ctxt;
         _objectCodec = codec;
         _parsingContext = XmlReadContext.createRootContext(-1, -1);
-        // and thereby start a scope
-        _nextToken = JsonToken.START_OBJECT;
         _xmlTokens = new XmlTokenStream(xmlReader, ctxt.getSourceReference(),
                 _formatFeatures);
+        switch (_xmlTokens.getCurrentToken()) {
+        case XmlTokenStream.XML_START_ELEMENT:
+            _nextToken = JsonToken.START_OBJECT;
+            break;
+        case XmlTokenStream.XML_NULL:
+            _nextToken = JsonToken.VALUE_NULL;
+            break;
+        default:
+            _reportError("Internal problem: invalid starting state (%d)", _xmlTokens.getCurrentToken());
+        }
     }
 
     @Override
@@ -462,11 +471,9 @@ public JsonToken nextToken() throws IOException
         }
         return t;
     }
-
-//    public JsonToken nextToken0() throws IOException
- */
-
+    */
 
+//    public JsonToken nextToken0() throws IOException
     @Override
     public JsonToken nextToken() throws IOException
     {
@@ -557,7 +564,7 @@ public JsonToken nextToken() throws IOException
                 _parsingContext = _parsingContext.getParent();
                 _namesToWrap = _parsingContext.getNamesToWrap();
                 return _currToken;
-                
+
             case XmlTokenStream.XML_ATTRIBUTE_NAME:
                 // If there was a chance of leaf node, no more...
                 if (_mayBeLeaf) {
@@ -615,6 +622,8 @@ public JsonToken nextToken() throws IOException
                 _parsingContext.setCurrentName(_cfgNameForTextElement);
                 _nextToken = JsonToken.VALUE_STRING;
                 return (_currToken = JsonToken.FIELD_NAME);
+            case XmlTokenStream.XML_NULL:
+                return (_currToken = JsonToken.VALUE_NULL);
             case XmlTokenStream.XML_END:
                 return (_currToken = null);
             }
@@ -732,6 +741,9 @@ public String nextTextValue() throws IOException
             _nextToken = JsonToken.VALUE_STRING;
             _currToken = JsonToken.FIELD_NAME;
             break;
+        case XmlTokenStream.XML_NULL:
+            _currToken = JsonToken.VALUE_STRING;
+            return (_currText = null);
         case XmlTokenStream.XML_END:
             _currToken = null;
         }

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

@@ -1,6 +1,8 @@
 package com.fasterxml.jackson.dataformat.xml.deser;
 
 import java.io.IOException;
+
+import javax.xml.XMLConstants;
 import javax.xml.stream.*;
 
 import org.codehaus.stax2.XMLStreamLocation2;
@@ -29,14 +31,19 @@ public class XmlTokenStream
     public final static int XML_ATTRIBUTE_NAME = 3;
     public final static int XML_ATTRIBUTE_VALUE = 4;
     public final static int XML_TEXT = 5;
-    public final static int XML_END = 6;
+    public final static int XML_NULL = 6; // since 2.10
+    public final static int XML_END = 7;
 
     // // // token replay states
 
     private final static int REPLAY_START_DUP = 1;
     private final static int REPLAY_END = 2;
     private final static int REPLAY_START_DELAYED = 3;
-
+
+    // Some helpful XML Constants
+
+    private final static String XSI_NAMESPACE = XMLConstants.W3C_XML_SCHEMA_INSTANCE_NS_URI;
+
     /*
     /**********************************************************************
     /* Configuration
@@ -64,6 +71,13 @@ public class XmlTokenStream
 
     protected int _attributeCount;
 
+    /**
+     * Marker used to indicate presence of `xsi:nil="true"' in current START_ELEMENT.
+     *
+     * @since 2.10
+     */
+    protected boolean _xsiNilFound;
+
     /**
      * If true we have a START_ELEMENT with mixed text
      *
@@ -76,7 +90,7 @@ public class XmlTokenStream
      * to return (as field name and value pair), if any; -1
      * when no attributes to return
      */
-    protected int _nextAttributeIndex = 0;
+    protected int _nextAttributeIndex;
 
     protected String _localName;
 
@@ -124,11 +138,17 @@ public XmlTokenStream(XMLStreamReader xmlReader, Object sourceRef,
                     +XMLStreamConstants.START_ELEMENT+"), instead got "+xmlReader.getEventType());
         }
         _xmlReader = Stax2ReaderAdapter.wrapIfNecessary(xmlReader);
-        _currentState = XML_START_ELEMENT;
         _localName = _xmlReader.getLocalName();
         _namespaceURI = _xmlReader.getNamespaceURI();
-        _attributeCount = _xmlReader.getAttributeCount();
         _formatFeatures = formatFeatures;
+
+        _checkXsiAttributes(); // sets _attributeCount, _nextAttributeIndex
+
+        if (_xsiNilFound) {
+            _currentState = XML_NULL;
+        } else {
+            _currentState = XML_START_ELEMENT;
+        }
     }
 
     public XMLStreamReader2 getXmlReader() {
@@ -200,10 +220,13 @@ public void skipEndElement() throws IOException, XMLStreamException
     public String getText() { return _textValue; }
     public String getLocalName() { return _localName; }
     public String getNamespaceURI() { return _namespaceURI; }
+
+    /*// not used as of 2.10
     public boolean hasAttributes() {
         return (_currentState == XML_START_ELEMENT) && (_attributeCount > 0);
     }
-
+    */
+
     public void closeCompletely() throws XMLStreamException {
         _xmlReader.closeCompletely();
     }
@@ -319,6 +342,13 @@ private final int _next() throws XMLStreamException
             ++_nextAttributeIndex;
             // fall through
         case XML_START_ELEMENT: // attributes to return?
+
+            // 06-Sep-2019, tatu: `xsi:nil` to induce "real" null value?
+            if (_xsiNilFound) {
+                _xsiNilFound = false;
+                return (_currentState = XML_NULL);
+            }
+
             if (_nextAttributeIndex < _attributeCount) {
                 _localName = _xmlReader.getAttributeLocalName(_nextAttributeIndex);
                 _namespaceURI = _xmlReader.getAttributeNamespace(_nextAttributeIndex);
@@ -358,11 +388,23 @@ private final int _next() throws XMLStreamException
             }
             // text followed by END_ELEMENT
             return _handleEndElement();
+        case XML_NULL:
+            // at this point we are pointing to START_ELEMENT, need to find
+            // matching END_ELEMENT, handle it
+            // 06-Sep-2019, tatu: Should handle error cases better but for now this'll do
+            switch (_skipUntilTag()) {
+            case XMLStreamConstants.END_ELEMENT:
+                return _handleEndElement();
+            case XMLStreamConstants.END_DOCUMENT:
+                throw new IllegalStateException("Unexpected end-of-input after null token");
+            default:
+                throw new IllegalStateException("Unexpected START_ELEMENT after null token");
+            }
+
         case XML_END:
             return XML_END;
 //            throw new IllegalStateException("No more XML tokens available (end of input)");
         }
-
         // Ok: must be END_ELEMENT; see what tag we get (or end)
         switch (_skipUntilTag()) {
         case XMLStreamConstants.END_DOCUMENT:
@@ -463,13 +505,22 @@ private final String _getText(XMLStreamReader2 r) throws XMLStreamException
     /* Internal methods, other
     /**********************************************************************
      */
+
+    /*
+        _xmlReader = Stax2ReaderAdapter.wrapIfNecessary(xmlReader);
+        _currentState = XML_START_ELEMENT;
+        _localName = _xmlReader.getLocalName();
+        _namespaceURI = _xmlReader.getNamespaceURI();
+        _attributeCount = _xmlReader.getAttributeCount();
+        _formatFeatures = formatFeatures;
+     */
 
     private final int _initStartElement() throws XMLStreamException
     {
         final String ns = _xmlReader.getNamespaceURI();
         final String localName = _xmlReader.getLocalName();
-        _attributeCount = _xmlReader.getAttributeCount();
-        _nextAttributeIndex = 0;
+
+        _checkXsiAttributes();
 
         /* Support for virtual wrapping: in wrapping, may either
          * create a new wrapper scope (if in sub-tree, or matches
@@ -497,6 +548,30 @@ private final int _initStartElement() throws XMLStreamException
         return (_currentState = XML_START_ELEMENT);
     }
 
+    /**
+     * @since 2.10
+     */
+    private final void _checkXsiAttributes() {
+        int count = _xmlReader.getAttributeCount();
+        _attributeCount = count;
+
+        // [dataformat-xml#354]: xsi:nul handling; at first only if first attribute
+        if (count >= 1) {
+            if ("nil".equals(_xmlReader.getAttributeLocalName(0))) {
+                if (XSI_NAMESPACE.equals(_xmlReader.getAttributeNamespace(0))) {
+                    // need to skip, regardless of value
+                    _nextAttributeIndex = 1;
+                    // but only mark as nil marker if enabled
+                    _xsiNilFound = "true".equals(_xmlReader.getAttributeValue(0));
+                    return;
+                }
+            }
+        }
+
+        _nextAttributeIndex = 0;
+        _xsiNilFound = false;
+    }
+
     /**
      * Method called to handle details of repeating "virtual"
      * start/end elements, needed for handling 'unwrapped' lists.

src/test/java/com/fasterxml/jackson/dataformat/xml/deser/SimpleStringValuesTest.java

@@ -99,7 +99,10 @@ public void testEmptyElementToString() throws Exception
 "</a>\n";
         Issue167Bean result = MAPPER.readValue(XML, Issue167Bean.class);
         assertNotNull(result);
-        assertEquals("", result.d);
+        // 06-Sep-2019, tatu: As per [dataformat-xml#354] this should now (2.10)
+        //    produce real `null`:
+//        assertEquals("", result.d);
+        assertNull(result.d);
     }
 
     /*

src/test/java/com/fasterxml/jackson/dataformat/xml/failing/XsiNil354Test.java

@@ -19,18 +19,42 @@ public DoubleWrapper(Double value) {
     public void testWithDoubleAsNull() throws Exception
     {
         DoubleWrapper bean = MAPPER.readValue(
-                "<DoubleWrapper xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"><d xsi:nil='true'></DoubleWrapper>",
+"<DoubleWrapper xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"><d xsi:nil='true' /></DoubleWrapper>",
                 DoubleWrapper.class);
         assertNotNull(bean);
         assertNull(bean.d);
+
+        bean = MAPPER.readValue(
+"<DoubleWrapper xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"><d xsi:nil='true'>  </d></DoubleWrapper>",
+                DoubleWrapper.class);
+        assertNotNull(bean);
+        assertNull(bean.d);
+
+        // actually we should perhaps also verify there is no content but... for now, let's leave it.
     }
 
     public void testWithDoubleAsNonNull() throws Exception
     {
         DoubleWrapper bean = MAPPER.readValue(
-                "<DoubleWrapper xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"><d xsi:nil='false'>0.25</DoubleWrapper>",
+                "<DoubleWrapper xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"><d xsi:nil='false'>0.25</d></DoubleWrapper>",
                 DoubleWrapper.class);
         assertNotNull(bean);
         assertEquals(Double.valueOf(0.25), bean.d);
     }
+
+    public void testRootPojoAsNull() throws Exception
+    {
+        Point bean = MAPPER.readValue(
+                "<Point xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xsi:nil='true' />",
+                Point.class);
+        assertNull(bean);
+    }
+
+    public void testRootPojoAsNonNull() throws Exception
+    {
+        Point bean = MAPPER.readValue(
+                "<Point xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xsi:nil='false'></Point>",
+                Point.class);
+        assertNotNull(bean);
+    }
 }