Support xsi:nil Attribute in xml to json/record conversion

ballerina/Ballerina.toml

@@ -1,19 +1,19 @@
 [package]
 org = "ballerina"
 name = "xmldata"
-version = "2.8.1"
+version = "2.9.0"
 authors = ["Ballerina"]
 keywords = ["xml", "json"]
 repository = "https://github.com/ballerina-platform/module-ballerina-xmldata"
 icon = "icon.png"
 license = ["Apache-2.0"]
-distribution = "2201.10.0"
+distribution = "2201.11.0"
 
 [platform.java21]
 graalvmCompatible = true
 
 [[platform.java21.dependency]]
 groupId = "io.ballerina.stdlib"
 artifactId = "xmldata-native"
-version = "2.8.1"
+version = "2.9.0"
 path = "../native/build/libs/xmldata-native-2.9.0-SNAPSHOT.jar"

ballerina/Dependencies.toml

@@ -5,7 +5,7 @@
 
 [ballerina]
 dependencies-toml-version = "2"
-distribution-version = "2201.11.0-20241112-214900-6b80ab87"
+distribution-version = "2201.11.0-20241209-162400-0c015833"
 
 [[package]]
 org = "ballerina"
@@ -67,7 +67,7 @@ modules = [
 [[package]]
 org = "ballerina"
 name = "xmldata"
-version = "2.8.1"
+version = "2.9.0"
 dependencies = [
 	{org = "ballerina", name = "jballerina.java"},
 	{org = "ballerina", name = "test"}

ballerina/tests/from_xml_test.bal

@@ -1294,3 +1294,65 @@ isolated function testFromXmlWithNameAnnotation() returns error? {
     Appointments result = check fromXml(xmlPayload);
     test:assertEquals(result, expected, msg = "testFromXmlWithNameAnnotation result incorrect");
 }
+
+@Name {
+    value: "book"
+}
+type Book record {|
+    string name;
+    BookDetails details;
+|};
+
+type BookDetails record {|
+    string? author;
+    string language;
+|};
+
+@test:Config {
+    groups: ["fromXml"]
+}
+function testFromXmlWithNilElementAndWithoutPreserveNS() returns Error? {
+    xml x1 = xml `<book><name>Sherlock Holmes</name>
+                  <details xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+                    <author xsi:nil="true"/>
+                    <language>English</language>
+                  </details></book>`;
+    Book expected = {
+        name: "Sherlock Holmes",
+        details: {
+            author: (),
+            language: "English"
+        }
+    };
+    Book result = check fromXml(x1);
+    test:assertEquals(result, expected, msg = "testFromXmlWithNilElement result incorrect");
+}
+
+@Name {
+    value: "book"
+}
+type Book1 record {|
+    string name;
+    BookDetails1 details;
+|};
+
+type BookDetails1 record {|
+    string author;
+    string language;
+|};
+
+@test:Config {
+    groups: ["fromXml"]
+}
+function testFromXmlWithNilElementAndWithoutNillableField() returns Error? {
+    xml x1 = xml `<book><name>Sherlock Holmes</name>
+                  <details xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+                    <author xsi:nil="true"/>
+                    <language>English</language>
+                  </details></book>`;
+    Book1|Error result = fromXml(x1);
+    test:assertTrue(result is error, msg = "testFromXmlWithNilElementAndWithoutNillableField result incorrect");
+    if (result is error) {
+        test:assertTrue(result.message().includes("field 'details.author' in record 'xmldata:BookDetails1' should be of type 'string', found '()'"));
+    }
+}

ballerina/tests/xml_from_json_test.bal

@@ -1096,3 +1096,13 @@ isolated function testWithRootTagConfig() {
         test:assertFail("failed to convert json to xml");
     }
 }
+
+@test:Config {
+    groups: ["fromJson"]
+}
+function testFromJsonWithNull() returns error? {
+    json data = null;
+    xml? result = check fromJson({"name":"Sherlock Holmes", "details":{"author":null, "language":"English"}}, {rootTag: "book"});
+    xml expected = xml `<book><name>Sherlock Holmes</name><details><author/><language>English</language></details></book>`;
+    test:assertEquals(result, expected, msg = "testFromJsonWithNull result incorrect");
+}

ballerina/tests/xml_to_json_test.bal

@@ -730,3 +730,30 @@ function testToJsonComplexXmlElementWithBackSlash() returns Error? {
     };
     test:assertEquals(j, expectedOutput, msg = "testToJsonComplexXmlElement result incorrect");
 }
+
+@test:Config {
+    groups: ["toJson"]
+}
+function testToJsonWithNilElementAndWithoutPreserveNS() returns Error? {
+    xml x1 = xml `<name>Sherlock Holmes</name>
+                  <details xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+                    <author xsi:nil="true"/>
+                    <language>English</language>
+                  </details>`;
+    json j = check toJson(x1, {preserveNamespaces: false});
+    test:assertEquals(j, {"name":"Sherlock Holmes", "details":{"author":null, "language":"English"}}, msg = "testToJsonWithNilElement result incorrect");
+}
+
+@test:Config {
+    groups: ["toJson"]
+}
+function testToJsonWithNilElementAndPreserveNS() returns Error? {
+    xml x1 = xml `<name>Sherlock Holmes</name>
+                  <details xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+                    <author xsi:nil="true"/>
+                    <language>English</language>
+                  </details>`;
+    json j = check toJson(x1, {preserveNamespaces: true});
+    test:assertEquals(j, {"name":"Sherlock Holmes","details":{"author":{"@xsi:nil":"true"},"language":"English",
+    "@xmlns:xsi":"http://www.w3.org/2001/XMLSchema-instance"}}, msg = "testToJsonWithNilElement result incorrect");
+}

changelog.md

@@ -6,6 +6,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+- [Add support for xsi:nil Attribute in xml to json/record conversion](https://github.com/ballerina-platform/ballerina-library/issues/7462)
+
+## [2.6.2] - 2023-08-17
+
 ### Fixed
 [Fix the mismatch error by `fromXml` API while the field has the name annotation](https://github.com/ballerina-platform/ballerina-standard-library/issues/3802)
 [Make some of the Java classes proper utility classes](https://github.com/ballerina-platform/ballerina-standard-library/issues/4902)

native/src/main/java/io/ballerina/stdlib/xmldata/XmlToJson.java

@@ -71,6 +71,8 @@ public class XmlToJson {
     private static final String EMPTY_STRING = "";
     public static final int NS_PREFIX_BEGIN_INDEX = BXmlItem.XMLNS_NS_URI_PREFIX.length();
     private static final String COLON = ":";
+    public static final String XMLSCHEMA_INSTANCE_NIL = "{http://www.w3.org/2001/XMLSchema-instance}nil";
+    public static final BString BSTRING_XMLSCHEMA_INSTANCE_NIL = fromString(XMLSCHEMA_INSTANCE_NIL);
 
     /**
      * Converts an XML to the corresponding JSON representation.
@@ -190,7 +192,13 @@ private static Object convertElement(BXmlItem xmlItem, String attributePrefix,
             children = convertToArray(fieldType, children);
         }
         fieldDetail.setParentArrayName(fieldName);
-        return insertDataToMap(childrenData, children, rootNode,  fieldName, fieldType, fieldDetail);
+        boolean nilValue = false;
+        // If the children is null and has `{http://www.w3.org/2001/XMLSchema-instance}nil` attribute set to true,
+        // then it is a nil value
+        if (children == null && attributeMap.containsKey(BSTRING_XMLSCHEMA_INSTANCE_NIL)) {
+            nilValue = Boolean.parseBoolean(attributeMap.get(BSTRING_XMLSCHEMA_INSTANCE_NIL).getValue());
+        }
+        return insertDataToMap(childrenData, children, rootNode,  fieldName, fieldType, fieldDetail, nilValue);
     }
 
     private static void processAttributeWithAnnotation(BXmlItem xmlItem, String attributePrefix,
@@ -224,7 +232,8 @@ private static void processAttributeWithAnnotation(BXmlItem xmlItem, String attr
     @SuppressWarnings("unchecked")
     private static BMap<BString, Object> insertDataToMap(BMap<BString, Object> childrenData, Object children,
                                                          BMap<BString, Object> rootNode, String keyValue,
-                                                         Type fieldType, FieldDetails fieldDetails) throws Exception {
+                                                         Type fieldType, FieldDetails fieldDetails, boolean nilValue)
+            throws Exception {
         if (childrenData.size() > 0) {
             if (children instanceof BMap) {
                 BMap<BString, Object> data = (BMap<BString, Object>) children;
@@ -248,9 +257,9 @@ private static BMap<BString, Object> insertDataToMap(BMap<BString, Object> child
                 put(rootNode, keyValue, children);
             } else if (children == null) {
                 if (fieldType instanceof ReferenceType && TypeUtils.getReferredType(fieldType) instanceof RecordType) {
-                    put(rootNode, keyValue, ValueCreator.createMapValue(Constants.JSON_MAP_TYPE));
+                    put(rootNode, keyValue, nilValue ? null : ValueCreator.createMapValue(Constants.JSON_MAP_TYPE));
                 } else {
-                    putAsFieldTypes(rootNode, keyValue, EMPTY_STRING, fieldType, fieldDetails);
+                    putAsFieldTypes(rootNode, keyValue, nilValue ? null : EMPTY_STRING, fieldType, fieldDetails);
                 }
             } else if (children instanceof BArray) {
                 put(rootNode, keyValue, children);
@@ -645,7 +654,7 @@ private static Object validateResult(Object result, BString elementName) {
         Object validateResult;
         if (result == null) {
             validateResult = fromString(EMPTY_STRING);
-        } else if (result instanceof BMap && ((BMap<?, ?>) result).get(elementName) != null) {
+        } else if (result instanceof BMap && ((BMap<?, ?>) result).containsKey(elementName)) {
             validateResult = ((BMap<?, ?>) result).get(elementName);
         } else {
             validateResult = result;