fix: Honor type hints when deserializing XML to JSON with empty string values

Fixes #66

Author: aalmiray

subprojects/json-lib-core/src/main/java/org/kordamp/json/util/JSONUtils.java

@@ -385,6 +385,30 @@ public static boolean isString(Object obj) {
         return false;
     }
 
+    /**
+     * <p>Determines whether a given string is <code>null</code>, empty,
+     * or only contains whitespace. If it contains anything other than
+     * whitespace then the string is not considered to be blank and the
+     * method returns <code>false</code>.</p>
+     *
+     * @param str The string to test.
+     * @return <code>   true</code> if the string is <code>null</code>, or
+     * blank.
+     */
+    public static boolean isBlank(String str) {
+        if (null == str || str.length() == 0) {
+            return true;
+        }
+
+        for (char c : str.toCharArray()) {
+            if (!Character.isWhitespace(c)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
     /**
      * Tests if the String possibly represents a valid JSON String.<br>
      * Valid JSON strings are:

subprojects/json-lib-core/src/main/java/org/kordamp/json/xml/XMLSerializer.java

@@ -59,6 +59,8 @@
 import java.util.Map;
 import java.util.TreeMap;
 
+import static org.kordamp.json.util.JSONUtils.isBlank;
+
 /**
  * Utility class for transforming JSON to XML an back.<br>
  * When transforming JSONObject and JSONArray instances to XML, this class will
@@ -560,9 +562,7 @@ public void setForcedArrayElements(Collection<String> forcedArrayElements) {
      * Creates a JSON value from a XML string.
      *
      * @param xml A well-formed xml document in a String
-     *
      * @return a JSONNull, JSONObject or JSONArray
-     *
      * @throws JSONException if the conversion from XML to JSON can't be made for
      *                       I/O or format reasons.
      */
@@ -600,9 +600,7 @@ public JSON read(String xml) {
      * Creates a JSON value from a File.
      *
      * @param file
-     *
      * @return a JSONNull, JSONObject or JSONArray
-     *
      * @throws JSONException if the conversion from XML to JSON can't be made for
      *                       I/O or format reasons.
      */
@@ -627,9 +625,7 @@ public JSON readFromFile(File file) {
      * Creates a JSON value from a File.
      *
      * @param path
-     *
      * @return a JSONNull, JSONObject or JSONArray
-     *
      * @throws JSONException if the conversion from XML to JSON can't be made for
      *                       I/O or format reasons.
      */
@@ -643,9 +639,7 @@ public JSON readFromFile(String path) {
      * Creates a JSON value from an input stream.
      *
      * @param stream
-     *
      * @return a JSONNull, JSONObject or JSONArray
-     *
      * @throws JSONException if the conversion from XML to JSON can't be made for
      *                       I/O or format reasons.
      */
@@ -767,9 +761,7 @@ public void setKeepArrayName(boolean keepName) {
      * Writes a JSON value into a XML string with UTF-8 encoding.<br>
      *
      * @param json The JSON value to transform
-     *
      * @return a String representation of a well-formed xml document.
-     *
      * @throws JSONException if the conversion from JSON to XML can't be made for
      *                       I/O reasons.
      */
@@ -783,9 +775,7 @@ public String write(JSON json) {
      *
      * @param json     The JSON value to transform
      * @param encoding The xml encoding to use
-     *
      * @return a String representation of a well-formed xml document.
-     *
      * @throws JSONException if the conversion from JSON to XML can't be made for
      *                       I/O reasons or the encoding is not supported.
      */
@@ -1193,7 +1183,9 @@ private Element processJSONObject(JSONObject jsonObject, Element root,
 
         Object[] names = jsonObject.names().toArray();
         List<String> unprocessed = new ArrayList<>();
-        if (isSortPropertyNames()) { Arrays.sort(names); }
+        if (isSortPropertyNames()) {
+            Arrays.sort(names);
+        }
         for (Object o : names) {
             String name = (String) o;
             Object value = jsonObject.get(name);
@@ -1275,7 +1267,6 @@ private Element processJSONObject(JSONObject jsonObject, Element root,
      * Only perform auto expansion if all children are objects.
      *
      * @param array The array to check
-     *
      * @return True if all children are objects, false otherwise.
      */
     private boolean canAutoExpand(JSONArray array) {
@@ -1557,7 +1548,11 @@ private void setValue(JSONObject jsonObject, Element element, String defaultType
                     params = StringUtils.split(paramsAttribute.getValue(), ",");
                     setOrAccumulate(jsonObject, key, new JSONFunction(params, text));
                 } else {
-                    if (isArray(element, false)) {
+                    Attribute typeAttr = element.getAttribute(addJsonPrefix("type"));
+                    if (typeAttr != null && isBlank(element.getValue()) &&
+                        element.getChildCount() == 0 && element.getChildElements().size() == 0) {
+                        setOrAccumulate(jsonObject, key, "");
+                    } else if (isArray(element, false)) {
                         setOrAccumulate(jsonObject, key, processArrayElement(element, defaultType));
                     } else if (isObject(element, false)) {
                         setOrAccumulate(jsonObject, key, simplifyValue(jsonObject,

subprojects/json-lib-core/src/test/java/org/kordamp/json/xml/TestUserSubmitted.java

@@ -221,16 +221,24 @@ public void testXMLWithoutArray() {
         Assertions.assertEquals(expected, actual);
     }
 
+    public void testEmptyStringWithHints() {
+        String testXML = "<o><test1 type=\"string\" /></o>";
+
+        JSON expected = JSONSerializer.toJSON("{\"o\": {\"test1\": \"\"}}");
+
+        JSONObject actual = convertXML(testXML);
+        assertNotNull(actual);
+        Assertions.assertEquals(expected, actual);
+    }
+
     private JSONObject convertXML(String testXML) {
-        JSON jsonElement = getSerializer().read(testXML);
-        return (JSONObject) jsonElement;
+        return (JSONObject) getSerializer().read(testXML);
     }
 
     private JSONObject convertXML(String testXML, String arrayName) {
         final XMLSerializer xmlSerializer = getSerializer();
         xmlSerializer.setArrayName(arrayName);
-        JSON jsonElement = xmlSerializer.read(testXML);
-        return (JSONObject) jsonElement;
+        return (JSONObject) xmlSerializer.read(testXML);
     }
 
     private XMLSerializer getSerializer() {