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Fix #344: null for polymorphic element of Collection (#829)
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Lines changed: 152 additions & 1 deletion

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‎src/main/java/tools/jackson/dataformat/xml/deser/FromXmlParser.java‎

Lines changed: 34 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -110,6 +110,16 @@ public class FromXmlParser
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*/
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protected boolean _nextIsLeadingMixed;
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/**
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* [dataformat-xml#344]: Flag set when a START_ELEMENT with xsi:nil is encountered
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* in the {@code _mayBeLeaf} path. When true, the subsequent END_ELEMENT should
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* produce {@code VALUE_NULL} instead of the empty-Object ({@code START_OBJECT}/{@code END_OBJECT})
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* pattern from [dataformat-xml#180].
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*
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* @since 3.2
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*/
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protected boolean _nextIsNullXsiNil;
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/*
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/**********************************************************************
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/* Parsing state, parsed values
@@ -120,7 +130,7 @@ public class FromXmlParser
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* ByteArrayBuilder is needed if 'getBinaryValue' is called. If so,
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* we better reuse it for remainder of content.
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*/
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protected ByteArrayBuilder _byteArrayBuilder = null;
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protected ByteArrayBuilder _byteArrayBuilder;
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/**
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* We will hold on to decoded binary data, for duration of
@@ -560,6 +570,10 @@ public JsonToken nextToken() throws JacksonException
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while (token == XmlTokenStream.XML_START_ELEMENT) {
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// If we thought we might get leaf, no such luck
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if (_mayBeLeaf) {
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// [dataformat-xml#344]: Record xsi:nil on the child element so that
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// the subsequent END_ELEMENT handler can produce VALUE_NULL instead of
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// the START_OBJECT/END_OBJECT empty-Object pattern from #180.
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_nextIsNullXsiNil = _xmlTokens.hasXsiNil();
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// leave _mayBeLeaf set, as we start a new context
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_nextToken = JsonToken.PROPERTY_NAME;
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_streamReadContext = _streamReadContext.createChildObjectContext(-1, -1);
@@ -568,7 +582,16 @@ public JsonToken nextToken() throws JacksonException
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if (_streamReadContext.inArray()) {
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// Yup: in array, so this element could be verified; but it won't be
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// reported anyway, and we need to process following event.
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// [dataformat-xml#344]: Check for xsi:nil BEFORE consuming the element;
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// if found, produce VALUE_NULL directly instead of falling through to
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// the #180 empty-Object handling (START_OBJECT/END_OBJECT) which breaks
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// polymorphic type resolution.
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final boolean xsiNil = _xmlTokens.hasXsiNil();
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token = _nextToken();
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if (xsiNil) {
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_streamReadContext.valueStarted();
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return _updateToken(JsonToken.VALUE_NULL);
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}
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_mayBeLeaf = true;
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continue;
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}
@@ -600,12 +623,22 @@ public JsonToken nextToken() throws JacksonException
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if (_mayBeLeaf) {
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_mayBeLeaf = false;
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if (_streamReadContext.inArray()) {
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// [dataformat-xml#344]: if the element had xsi:nil, produce
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// VALUE_NULL directly — polymorphic type resolvers cannot handle
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// the empty START_OBJECT/END_OBJECT from #180.
629+
if (_nextIsNullXsiNil) {
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_nextIsNullXsiNil = false;
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_streamReadContext.valueStarted();
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return _updateToken(JsonToken.VALUE_NULL);
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}
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// 06-Jan-2015, tatu: as per [dataformat-xml#180], need to
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// expose as empty Object, not null
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_nextToken = JsonToken.END_OBJECT;
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_streamReadContext = _streamReadContext.createChildObjectContext(-1, -1);
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return _updateToken(JsonToken.START_OBJECT);
608639
}
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// [dataformat-xml#344]: clear flag in non-array path too
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_nextIsNullXsiNil = false;
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// 07-Sep-2019, tatu: for [dataformat-xml#353], must NOT return second null
610643
if (_currToken != JsonToken.VALUE_NULL) {
611644
// 13-May-2020, tatu: [dataformat-xml#397]: advance `index`

‎src/test/java/tools/jackson/dataformat/xml/lists/PolymorphicListNullElement344Test.java‎

Lines changed: 118 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,118 @@
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package tools.jackson.dataformat.xml.lists;
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import java.util.ArrayList;
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import java.util.List;
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import org.junit.jupiter.api.Test;
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import com.fasterxml.jackson.annotation.*;
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import tools.jackson.databind.*;
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import tools.jackson.dataformat.xml.*;
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import static org.junit.jupiter.api.Assertions.*;
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/**
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* Test for [dataformat-xml#344]: Unable to deserialize null in polymorphic Collection.
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*<p>
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* With Jackson 3.x default of {@code WRITE_NULLS_AS_XSI_NIL = true},
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* null collection elements serialize as {@code <details xsi:nil="true"/>}.
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* The deserializer must recognize xsi:nil on array elements and produce
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* {@code VALUE_NULL} instead of {@code START_OBJECT}/{@code END_OBJECT}.
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*/
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public class PolymorphicListNullElement344Test extends XmlTestUtil
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{
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static class Master344 {
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public List<Detail344> details = new ArrayList<>();
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}
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@JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, property = "cl")
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static class Detail344 {
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public String value;
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protected Detail344() { }
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public Detail344(String v) { value = v; }
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}
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private final XmlMapper MAPPER = newMapper();
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// [dataformat-xml#344]: null element in polymorphic list, round-trip
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@Test
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public void testNullInPolymorphicListRoundTrip() throws Exception
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{
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Master344 master = new Master344();
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master.details.add(new Detail344("first"));
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master.details.add(null);
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master.details.add(new Detail344("third"));
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String xml = MAPPER.writeValueAsString(master);
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Master344 result = MAPPER.readValue(xml, Master344.class);
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assertNotNull(result);
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assertNotNull(result.details);
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assertEquals(3, result.details.size());
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assertNotNull(result.details.get(0));
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assertEquals("first", result.details.get(0).value);
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assertNull(result.details.get(1));
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assertNotNull(result.details.get(2));
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assertEquals("third", result.details.get(2).value);
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}
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// [dataformat-xml#344]: null element in polymorphic list, deserialize from xsi:nil XML
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@Test
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public void testNullInPolymorphicListFromXsiNil() throws Exception
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{
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String xml = "<Master344>"
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+ "<details>"
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+ "<details xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xsi:nil=\"true\"/>"
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+ "</details>"
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+ "</Master344>";
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Master344 result = MAPPER.readValue(xml, Master344.class);
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assertNotNull(result);
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assertNotNull(result.details);
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assertEquals(1, result.details.size());
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assertNull(result.details.get(0));
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}
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// [dataformat-xml#344]: only null elements in polymorphic list
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@Test
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public void testOnlyNullsInPolymorphicList() throws Exception
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{
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Master344 master = new Master344();
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master.details.add(null);
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String xml = MAPPER.writeValueAsString(master);
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Master344 result = MAPPER.readValue(xml, Master344.class);
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assertNotNull(result);
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assertNotNull(result.details);
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assertEquals(1, result.details.size());
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assertNull(result.details.get(0));
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}
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// [dataformat-xml#344]: multiple consecutive nulls in polymorphic list.
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// First null exercises _mayBeLeaf + END_ELEMENT path (fix site 1+3),
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// second null exercises inArray() path (fix site 2).
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@Test
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public void testMultipleNullsInPolymorphicList() throws Exception
101+
{
102+
Master344 master = new Master344();
103+
master.details.add(null);
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master.details.add(null);
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master.details.add(new Detail344("third"));
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107+
String xml = MAPPER.writeValueAsString(master);
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Master344 result = MAPPER.readValue(xml, Master344.class);
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assertNotNull(result);
111+
assertNotNull(result.details);
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assertEquals(3, result.details.size());
113+
assertNull(result.details.get(0));
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assertNull(result.details.get(1));
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assertNotNull(result.details.get(2));
116+
assertEquals("third", result.details.get(2).value);
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}
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}

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