XmlSerializer throws error when both class and superclass have a property with the XmlAnyElement attribute.

[santiagocabrera96]

When I run this code, it throws exception at line 26. If I take the property of the subclass or the superclass the exception is not thrown.

Code:

using System.IO;
using System.Text;
using System.Xml;
using System.Xml.Serialization;

namespace ConsoleApplication1
{
    public class Program
    {
        static void Main()
        {
            Obj2 obj2 = ParseFromXml<Obj2>(@"C:\Users\user\Downloads\CollectionOfObjects.xml");
            Serialize<Obj2>(obj2, @"C:\Users\user\Downloads\CollectionOfObjects-copy.xml");
        }
        public class Obj1
        {
            [XmlAnyElement] public XmlElement[] elements { get; set; }
        }
        [XmlType("CollectionOfObjects")]
        public class Obj2 : Obj1
        {
            [XmlAnyElement] public XmlElement[] elementos { get; set; }
        }
        private static T ParseFromXml<T>(string ruta)
        {
            var xs = new XmlSerializer(typeof(T));
            using (Stream s = File.OpenRead(ruta))
                return (T)xs.Deserialize(s);
        }
        private static void Serialize<T>(T obj, string path)
        {
            var xs = new XmlSerializer(typeof(T));
            var settings = new XmlWriterSettings { Encoding = Encoding.UTF8, Indent = true };
            if (!Directory.Exists(Path.GetDirectoryName(path)))
                Directory.CreateDirectory(Path.GetDirectoryName(path));
            using (var xmlWriter = XmlWriter.Create(path, settings))
            {
                var ns = new XmlSerializerNamespaces();
                ns.Add("", "");
                xs.Serialize(xmlWriter, obj, ns);
            }
        }
    }
}

CollectionOfObjects.xml

<CollectionOfObjects>
  <Name>Something</Name>
  <Description>Some description.</Description>
  <Object>
    <Name>Name Of Object</Name>
    <Description>Description of object.</Description>
    <AltName>Alternate name</AltName>
    <ContainerName>Container</ContainerName>
    <Required>true</Required>
    <Length>1</Length>
    <Info>
      <Name>Name</Name>
      <File>Filename</File>
      <Size>20</Size>
      <SizeUnit>MB</SizeUnit>
    </Info>
  </Object>
</CollectionOfObjects>

Exception:

System.InvalidOperationException was unhandled
  HResult=-2146233079
  Message=There was an error reflecting type 'ConsoleApplication1.Program.Obj2'.
  Source=System.Xml
  StackTrace:
       at System.Xml.Serialization.XmlReflectionImporter.ImportTypeMapping(TypeModel model, String ns, ImportContext context, String dataType, XmlAttributes a, Boolean repeats, Boolean openModel, RecursionLimiter limiter)
       at System.Xml.Serialization.XmlReflectionImporter.ImportElement(TypeModel model, XmlRootAttribute root, String defaultNamespace, RecursionLimiter limiter)
       at System.Xml.Serialization.XmlReflectionImporter.ImportTypeMapping(Type type, XmlRootAttribute root, String defaultNamespace)
       at System.Xml.Serialization.XmlSerializer..ctor(Type type, String defaultNamespace)
       at System.Xml.Serialization.XmlSerializer..ctor(Type type)
       at ConsoleApplication1.Program.ParseFromXml[T](String ruta) in C:\Users\user\Downloads\ConsoleApplication1\ConsoleApplication1\Program.cs:line 26
       at ConsoleApplication1.Program.Main() in C:\Users\user\Downloads\ConsoleApplication1\ConsoleApplication1\Program.cs:line 12
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException: 
       HResult=-2146233079
       Message=There was an error reflecting property 'elementos'.
       Source=System.Xml
       StackTrace:
            at System.Xml.Serialization.XmlReflectionImporter.InitializeStructMembers(StructMapping mapping, StructModel model, Boolean openModel, String typeName, RecursionLimiter limiter)
            at System.Xml.Serialization.XmlReflectionImporter.ImportStructLikeMapping(StructModel model, String ns, Boolean openModel, XmlAttributes a, RecursionLimiter limiter)
            at System.Xml.Serialization.XmlReflectionImporter.ImportTypeMapping(TypeModel model, String ns, ImportContext context, String dataType, XmlAttributes a, Boolean repeats, Boolean openModel, RecursionLimiter limiter)
       InnerException: 
            HResult=-2146233079
            Message=The XML element '' from namespace '' is already present in the current scope. Use XML attributes to specify another XML name or namespace for the element.
            Source=System.Xml
            StackTrace:
                 at System.Xml.Serialization.XmlReflectionImporter.AddUniqueAccessor(INameScope scope, Accessor accessor)
                 at System.Xml.Serialization.XmlReflectionImporter.AddUniqueAccessor(MemberMapping member, INameScope elements, INameScope attributes, Boolean isSequence)
                 at System.Xml.Serialization.XmlReflectionImporter.InitializeStructMembers(StructMapping mapping, StructModel model, Boolean openModel, String typeName, RecursionLimiter limiter)
            InnerException: 

[karelz]

Please re-paste the files & exception as text above, so that they are copy-able & searchable -- pictures are fairly useless :(
See how to do syntax-highlighting on GitHub (works for C# & xml): https://help.github.com/articles/creating-and-highlighting-code-blocks/

[santiagocabrera96]

@karelz Thanks for the reply. Updated the issue with the files as text.

[karelz]

@santiagocabrera96 thanks! Please update the exception as well.

[santiagocabrera96]

@karelz Done!

[jiayi11]

Hi @santiagocabrera96, thank you for reporting this issue.
The exception is supposed to be thrown in this case.
The derived class Obj2 gains property "elements" with XmlAnyElement attribute from base class Obj1. And it also has another property "elementos' with XmlAnyElement attribute. When there are more than one properties with XmlAnyElement attribute in a type, each property must have a distinct Name property value. To do this, you can specify the name of the xml element like [XmlAnyElement(Name="elementname")].
You can read more about XmlAnyElement attribute here.
Let me know if it helps 😄

[jiayi11]

I'm closing this issue, but feel free to comment or reopen it if you still have questions.