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Fix XmlDeserializer when XML uses same tag in nested elements #2336

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Fix XmlDeserializer when XML uses same tag in nested elements #2336

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125 changes: 102 additions & 23 deletions src/RestSharp.Serializers.Xml/XmlDeserializer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -40,8 +40,16 @@ public class XmlDeserializer : IXmlDeserializer, IWithRootElement, IWithDateForm
var root = doc.Root;
var rootElement = response.RootElement ?? RootElement;

if (rootElement != null && doc.Root != null)
root = doc.Root.DescendantsAndSelf(rootElement.AsNamespaced(Namespace)).SingleOrDefault();
if (rootElement != null && doc.Root != null) {
var namespacedRoot = rootElement.AsNamespaced(Namespace);
// Prefer shallowest match to avoid nested elements with same name
root = namespacedRoot != null
? doc.Root.Element(namespacedRoot)
?? doc.Root.DescendantsAndSelf(namespacedRoot)
.OrderBy(e => e.Ancestors().Count())
.FirstOrDefault()
: null;
}

// autodetect xml namespace
if (Namespace.IsEmpty())
Expand Down Expand Up @@ -76,10 +84,16 @@ static void RemoveNamespace(XDocument xdoc) {
? new(XNamespace.None.GetName(a.Name.LocalName), a.Value)
: a
)
.Where(a => a != null)
);
}
}

static bool IsValidXmlElementName(string name) {
// Generic type names contain backtick (e.g., "List`1") which is invalid in XML element names
return !name.Contains('`');
}

protected virtual object Map(object x, XElement? root) {
var objType = x.GetType();
var props = objType.GetProperties();
Expand Down Expand Up @@ -236,7 +250,20 @@ protected virtual object Map(object x, XElement? root) {
}
else if (type.IsGenericType) {
var list = (IList)Activator.CreateInstance(asType)!;
var container = GetElementByName(root, name);
XElement? container = null;

// First check if root itself is the container (matches property name)
if (root != null && name?.LocalName != null) {
var rootName = root.Name.LocalName;
if (rootName.Equals(name.LocalName, StringComparison.OrdinalIgnoreCase)) {
container = root;
}
}

// If root is not the container, try to find it as a child element
if (container == null) {
container = GetElementByName(root, name);
}

if (container?.HasElements == true) {
var first = container.Elements().FirstOrDefault();
Expand Down Expand Up @@ -306,37 +333,89 @@ object HandleListDerivative(XElement root, string propName, Type type) {

var list = (IList)Activator.CreateInstance(type)!;

IList<XElement> elements = root.Descendants(t.Name.AsNamespaced(Namespace)).ToList();

var name = t.Name;
var attribute = t.GetAttribute<DeserializeAsAttribute>();

if (attribute != null)
name = attribute.Name;

if (!elements.Any()) {
var lowerName = name?.ToLower(Culture).AsNamespaced(Namespace);

elements = root.Descendants(lowerName).ToList();
// Try to find a container element first using property name
XElement? container = null;

// Try property name first (skip if it contains invalid XML name characters like ` in generic types)
if (IsValidXmlElementName(propName)) {
container = GetElementByName(root, propName.AsNamespaced(Namespace));
}

if (!elements.Any()) {
var camelName = name?.ToCamelCase(Culture).AsNamespaced(Namespace);

elements = root.Descendants(camelName).ToList();

// Check if root itself matches the container naming
if (container == null && IsValidXmlElementName(propName)) {
var rootName = root.Name.LocalName;
var propNameLower = propName.ToLower(Culture);

if (rootName.Equals(propName, StringComparison.OrdinalIgnoreCase) ||
rootName.Equals(propNameLower, StringComparison.OrdinalIgnoreCase)) {
container = root;
}
}

IList<XElement> elements;

// If we found a container, get only its direct children (Elements)
if (container != null && container.HasElements) {
// Try to match item elements by name variations
var itemName = t.Name.AsNamespaced(Namespace);
var directChildren = container.Elements(itemName).ToList();

if (!directChildren.Any()) {
var lowerName = name?.ToLower(Culture).AsNamespaced(Namespace);
directChildren = container.Elements(lowerName).ToList();
}

if (!directChildren.Any()) {
var camelName = name?.ToCamelCase(Culture).AsNamespaced(Namespace);
directChildren = container.Elements(camelName).ToList();
}

if (!directChildren.Any()) {
directChildren = container.Elements()
.Where(e => e.Name.LocalName.RemoveUnderscoresAndDashes() == name)
.ToList();
}

if (!directChildren.Any()) {
var lowerName = name?.ToLower(Culture);
directChildren = container.Elements()
.Where(e => e.Name.LocalName.RemoveUnderscoresAndDashes() == lowerName)
.ToList();
}

elements = directChildren;
}
else {
// Fallback: No container found, use Descendants for backward compatibility
elements = root.Descendants(t.Name.AsNamespaced(Namespace)).ToList();

if (!elements.Any())
elements = root.Descendants()
.Where(e => e.Name.LocalName.RemoveUnderscoresAndDashes() == name)
.ToList();
if (!elements.Any()) {
var lowerName = name?.ToLower(Culture).AsNamespaced(Namespace);
elements = root.Descendants(lowerName).ToList();
}

if (!elements.Any()) {
var lowerName = name?.ToLower(Culture).AsNamespaced(Namespace);
if (!elements.Any()) {
var camelName = name?.ToCamelCase(Culture).AsNamespaced(Namespace);
elements = root.Descendants(camelName).ToList();
}

elements = root.Descendants()
.Where(e => e.Name.LocalName.RemoveUnderscoresAndDashes() == lowerName)
.ToList();
if (!elements.Any())
elements = root.Descendants()
.Where(e => e.Name.LocalName.RemoveUnderscoresAndDashes() == name)
.ToList();

if (!elements.Any()) {
var lowerName = name?.ToLower(Culture);
elements = root.Descendants()
.Where(e => e.Name.LocalName.RemoveUnderscoresAndDashes() == lowerName)
.ToList();
}
}

PopulateListFromElements(t, elements, list);
Expand Down
25 changes: 25 additions & 0 deletions test/RestSharp.Tests.Serializers.Xml/SampleClasses/NestedElementTestClasses.cs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,25 @@
namespace RestSharp.Tests.Serializers.Xml.SampleClasses;

// Test classes for nested element bugs

public class Item {
public int Id { get; set; }
public List<Item> SubItems { get; set; }
}

public class ItemContainer {
public List<Item> Items { get; set; } = new();
}

public class ItemWithGroup {
public int Id { get; set; }
public ItemGroup Group { get; set; }
}

public class ItemGroup {
public List<Item> Items { get; set; }
}

public class ItemsResponse {
public List<ItemWithGroup> Items { get; set; } = new();
}
166 changes: 165 additions & 1 deletion test/RestSharp.Tests.Serializers.Xml/XmlDeserializerTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1076,4 +1076,168 @@ public void Ignore_ReadOnly_Property_That_Exists_In_Data() {

Assert.Null(p.ReadOnlyProxy);
}
}

[Fact]
public void Deserialize_Nested_List_Should_Not_Include_Deeply_Nested_Items() {
// Bug #1 test: HandleListDerivative should use Elements() on containers, not Descendants()
const string xml = """
<root>
<items>
<item>
<id>1</id>
<subitems>
<item><id>2</id></item>
<item><id>3</id></item>
</subitems>
</item>
</items>
</root>
""";

var deserializer = new XmlDeserializer();
var result = deserializer.Deserialize<ItemContainer>(new RestResponse { Content = xml })!;

// Should only have 1 item (id=1), not 3 (id=1,2,3)
Assert.NotNull(result);
Assert.NotNull(result.Items);
Assert.Single(result.Items);
Assert.Equal(1, result.Items[0].Id);
}

[Fact]
public void Deserialize_RootElement_Should_Not_Throw_On_Duplicate_Nested_Names() {
// Bug #2 test: RootElement selection should handle duplicate names gracefully
const string xml = """
<root>
<items>
<item>
<id>72</id>
<group>
<items>
<item><id>74</id></item>
</items>
</group>
</item>
</items>
</root>
""";

var deserializer = new XmlDeserializer { RootElement = "items" };

// Should not throw InvalidOperationException: Sequence contains more than one element
var exception = Record.Exception(() =>
deserializer.Deserialize<ItemsResponse>(new RestResponse { Content = xml })
);

Assert.Null(exception);
}

[Fact]
public void Deserialize_RootElement_Should_Prefer_Shallowest_Match() {
// Bug #2 test: When multiple elements match RootElement, prefer the shallowest one
const string xml = """
<root>
<items>
<item>
<id>72</id>
<group>
<items>
<item><id>74</id></item>
</items>
</group>
</item>
</items>
</root>
""";

var deserializer = new XmlDeserializer { RootElement = "items" };
var result = deserializer.Deserialize<ItemsResponse>(new RestResponse { Content = xml })!;

// Should deserialize from the top-level <items>, not the nested one
Assert.NotNull(result);
Assert.NotNull(result.Items);
Assert.Single(result.Items);
Assert.Equal(72, result.Items[0].Id);
}

[Fact]
public void Deserialize_RootElement_Should_Try_Direct_Child_First() {
// Bug #2 test: Should try Element() before DescendantsAndSelf()
const string xml = """
<root>
<data>
<one>direct</one>
</data>
</root>
""";

var deserializer = new XmlDeserializer { RootElement = "data" };
var result = deserializer.Deserialize<SimpleStruct>(new RestResponse { Content = xml });

Assert.Equal("direct", result.One);
}

[Fact]
public void Deserialize_List_With_Container_Should_Use_Direct_Children_Only() {
// Test that container-based list deserialization uses Elements() not Descendants()
const string xml = """
<root>
<items>
<item>
<id>10</id>
<subitems>
<item><id>20</id></item>
</subitems>
</item>
<item>
<id>11</id>
</item>
</items>
</root>
""";

var deserializer = new XmlDeserializer();
var result = deserializer.Deserialize<ItemContainer>(new RestResponse { Content = xml })!;

Assert.NotNull(result.Items);
Assert.Equal(2, result.Items.Count);
Assert.Equal(10, result.Items[0].Id);
Assert.Equal(11, result.Items[1].Id);
}

[Fact]
public void Deserialize_Nested_Items_Should_Also_Use_Direct_Children() {
// Test that nested subitems also correctly use direct children
const string xml = """
<root>
<items>
<item>
<id>1</id>
<subitems>
<item><id>2</id></item>
<item>
<id>3</id>
<subitems>
<item><id>4</id></item>
</subitems>
</item>
</subitems>
</item>
</items>
</root>
""";

var deserializer = new XmlDeserializer();
var result = deserializer.Deserialize<ItemContainer>(new RestResponse { Content = xml })!;

Assert.NotNull(result.Items);
Assert.Single(result.Items);

var topItem = result.Items[0];
Assert.Equal(1, topItem.Id);
Assert.NotNull(topItem.SubItems);
Assert.Equal(2, topItem.SubItems.Count);
Assert.Equal(2, topItem.SubItems[0].Id);
Assert.Equal(3, topItem.SubItems[1].Id);
}
}
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