Serialize to actual json array/object

FasterXML · Mar 2, 2024 · e763443 · e763443
1 parent daf6dfa
commit e763443
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diff --git a/src/main/java/com/fasterxml/jackson/dataformat/xml/XmlFactoryBuilder.java b/src/main/java/com/fasterxml/jackson/dataformat/xml/XmlFactoryBuilder.java
@@ -59,6 +59,10 @@ public class XmlFactoryBuilder extends TSFBuilder<XmlFactory, XmlFactoryBuilder>
      *<p>
      * Value used for pseudo-property used for returning empty XML tag.
      * Defaults to empty String, but may be changed.
+     *
+     * In case of deserialization/serialization to JSON via JsonNode
+     * and _valueForEmptyElement is equals to [] or {}, the JSON will be serialized
+     * with actual empty json array or object instead of text value ("[]" or "{}")
      */
     protected String _valueForEmptyElement = FromXmlParser.DEFAULT_EMPTY_ELEMENT_VALUE;
 

diff --git a/src/main/java/com/fasterxml/jackson/dataformat/xml/deser/FromXmlParser.java b/src/main/java/com/fasterxml/jackson/dataformat/xml/deser/FromXmlParser.java
@@ -866,6 +866,19 @@ public JsonToken nextToken() throws IOException
                     //   expose "XmlText" as separate property
                     token = _nextToken();
 
+                    // Handle JSON object
+                    if (currentValue() == null && _xmlTokens._emptyElement) {
+                        if ("[]".equals(_currText)) {
+                            _nextToken = JsonToken.END_ARRAY;
+                            _parsingContext = _parsingContext.createChildArrayContext(-1, -1);
+                            return (_currToken = JsonToken.START_ARRAY);
+                        } else if ("{}".equals(_currText)) {
+                            _nextToken = JsonToken.END_OBJECT;
+                            _parsingContext = _parsingContext.createChildObjectContext(-1, -1);
+                            return (_currToken = JsonToken.START_OBJECT);
+                        }
+                    }
+
                     if (token == XmlTokenStream.XML_END_ELEMENT) {
                         if (_parsingContext.inArray()) {
                             if (XmlTokenStream._allWs(_currText)) {

diff --git a/src/main/java/com/fasterxml/jackson/dataformat/xml/deser/XmlTokenStream.java b/src/main/java/com/fasterxml/jackson/dataformat/xml/deser/XmlTokenStream.java
@@ -122,6 +122,11 @@ public class XmlTokenStream
 
     protected final String _valueForEmptyElement;
 
+    /**
+     * true if the current tag is empty
+     */
+    protected boolean _emptyElement;
+
     /**
      * Marker flag set if caller wants to "push back" current token so
      * that next call to {@link #next()} should simply be given what was
@@ -190,6 +195,7 @@ public XmlTokenStream(XMLStreamReader xmlReader, ContentReference sourceRef,
         _xmlReader = Stax2JacksonReaderAdapter.wrapIfNecessary(xmlReader);
         _nameProcessor = nameProcessor;
         _valueForEmptyElement = valueForEmptyElement;
+        _emptyElement = false;
     }
 
     /**
@@ -569,13 +575,15 @@ private final String _collectUntilTag() throws XMLStreamException
     {
         // 21-Jun-2017, tatu: Whether exposed as `null` or "" is now configurable...
         if (_xmlReader.isEmptyElement()) {
+            _emptyElement = true;
             _xmlReader.next();
             if (FromXmlParser.Feature.EMPTY_ELEMENT_AS_NULL.enabledIn(_formatFeatures)) {
                 return null;
             }
             return _valueForEmptyElement;
         }
 
+        _emptyElement = false;
         CharSequence chars = null;
         main_loop:
         while (_xmlReader.hasNext()) {

diff --git a/src/test/java/com/fasterxml/jackson/dataformat/xml/deser/EmptyStringValueTest.java b/src/test/java/com/fasterxml/jackson/dataformat/xml/deser/EmptyStringValueTest.java
@@ -5,6 +5,8 @@
 
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.dataformat.xml.XmlMapper;
 import com.fasterxml.jackson.dataformat.xml.XmlTestBase;
 import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty;
@@ -105,6 +107,42 @@ public void testEmptyElementEmptyArray() throws Exception
         assertEquals("", name.last);
     }
 
+    public void testEmptyElementFromXmlToJsonArray() throws Exception
+    {
+        final String xml = "<name><first/><last>[]</last></name>";
+
+        XmlMapper xmlMapper = XmlMapper.builder()
+                .valueForEmptyElement("[]")
+                .build();
+        JsonNode jsonNode = xmlMapper.readValue(xml, JsonNode.class);
+
+        ObjectMapper mapper = new ObjectMapper();
+        String json = mapper.writeValueAsString(jsonNode);
+
+        // first is an empty tag, and is expected to be serialized
+        // as an empty json array, last is not empty, and is serialized as text value
+        String expectedJson = "{\"first\":[],\"last\":\"[]\"}";
+        assertEquals(expectedJson, json);
+    }
+
+    public void testEmptyElementFromXmlToJsonObject() throws Exception
+    {
+        final String xml = "<name><first/><last>{}</last></name>";
+
+        XmlMapper xmlMapper = XmlMapper.builder()
+                .valueForEmptyElement("{}")
+                .build();
+        JsonNode jsonNode = xmlMapper.readValue(xml, JsonNode.class);
+
+        ObjectMapper mapper = new ObjectMapper();
+        String json = mapper.writeValueAsString(jsonNode);
+
+        // first is an empty tag, and is expected to be serialized
+        // as an empty json object, last is not empty, and is serialized as text value
+        String expectedJson = "{\"first\":{},\"last\":\"{}\"}";
+        assertEquals(expectedJson, json);
+    }
+
     public void testEmptyStringElement() throws Exception
     {
         // then with empty element