XmlSerializer don't load after first missing property

[goyometeojorito]

Describe the bug

When an object from a WCF API is deserialized, if that API has a new property that does NOT exist in the model, all data in the document after that property is not loaded, even if it exists in the model.

If a property has the [XmlAnyElement] attribute, all unread values ​​are saved there (even though the model DOES have those attributes).

All properties are loaded correctly even though the XML does not include the property that triggers the error.

An important detail is that if a base object has the [XmlAnyElement] property, all classes that inherit from it are NOT deserialized; all their values ​​are hijacked by the attribute, even if an Order value is set to very high.

Using DataContract is not a viable option, as svcutil generates numerous errors when using that serializer (all are of this type).

Warning: The optional WSDL extension element "body" from the namespace "http://schemas.xmlsoap.org/wsdl/soap12/" was not handled.
XPath: //wsdl:definitions[@targetNamespace='http://tempuri.org/']/wsdl:binding[@name='NetHttpBinding_IWebServiceHttp']/wsdl:operation[@name='TaskNewChange']/wsdl:output

To Reproduce
Steps to reproduce the behavior:

1. Create an API with the netTcpBinding protocol in .NET 4.5 with a method that returns an object with multiple properties.

2. In a .NET Maui version 9 project, add the reference to the WCF service.

3. Modify the API of the first project to add a new, optional, nullable property (ordered among the other properties, so that the new property isn't last).

4. (WITHOUT updating the references) When calling the API from the Maui project, when loading the data, ALL the properties that were after the new property are NOT loaded.

Expected behavior

New node values ​​from the XML that do not exist in the model should be ignored or stored in the property with the [XmlAnyElement] attribute and respecting inheritance. Since a Base object hijacks values ​​and should not

Screenshots

Cut of the XML response.

                <Row i:nil="true"></Row>
                <Seeds i:nil="true"></Seeds>
              </TrialItemVariety>
            </TrialItemVarieties>
            <WaterEC></WaterEC>
            <WetDate i:nil="true"></WetDate>
            <Zone i:nil="true"></Zone>
          </TrialItem>
        </Items>
        <PreparationInstructions i:nil="true"></PreparationInstructions>
        <Remarks>Example value</Remarks>
        <Season>Winter</Season>
        <State>Planning</State>
        <Technical i:nil="true"></Technical>
        <Time i:nil="true"></Time>
        <TrialLot></TrialLot>
        <TrialVarieties>
          <TrialVariety>
            <Extractions></Extractions>
            <Id>c53f3a22-c9b0-4b90-b62c-fc3a0bcf9875</Id>
            <IdAccession>69528d60-ca21-4412-a2b2-d087337fbf60</IdAccession>
            <IdTrialExtra>14687ec7-b19e-499b-809f-0a6c8abcf7c2</IdTrialExtra>
          </TrialVariety>

Look que end node (Items has values inside)
Look PreparationInstructions it's the new property not in model
Look Remarks and Season has value
Look TrialVarieties has items inside
Look State Planning it's not load (this value it's the default)

Adding to the model a property with XmlAnyElement all nodes after the missing it's added to XmlAnyElementProperty and not loaded

Additional context

It is important that the data loading is robust, since an API can be updated with optional parameters and that should not break the loading.

[mconnew]

Can you provide the data class that's having the problem for the server and the client as they are different. I suspect this is a by-design case where you are bumping into a behavior that's intentional but causes you problems.

[goyometeojorito]

I've created a clean project to test this issue using a simpler model.

[Repo TestXmlSerializationInMaui]

In MauiProgram.cs, I've put the code for testing. It consists of an "ExampleClass" class with four text properties and these two XML files for deserialization.

<ExampleClass xmlns="testnamespace">
	<A>ValueA</A>
	<B>ValueB</B>
	<C>ValueC</C>
	<D>ValueD</D>
</ExampleClass>

<ExampleClass xmlns="testnamespace">
	<A>ValueA</A>
	<B>ValueB</B>
	<PropertyNew>This can be ignored</PropertyNew>
	<C>ValueC</C>
	<D>ValueD</D>
</ExampleClass>

The idea is to ignore the PropertyNew node when loading. But if it reads the values ​​C and D

If you look the code in my example MauiProgram.cs
In objOk, the clean XML loads correctly (as usual).
In objBad, properties C and D aren't loaded.

I had a suspicion about the "Order" attribute that the svcutil tool adds to classes when generating the proxy code, so I created an ExampleClassWithoutOrder class, which is the same as the previous one, but without the Order value. The second test correctly ignores the PropertyNew node and correctly loads the other properties.

So I think the deserializer is using the Order attribute to validate the XML loading. Since there's a new property, the position of the lower nodes no longer matches, and it doesn't load them. I thought the Order attribute only affected serialization (so the document is generated in that order), but I never thought it was used when loading the document. That makes any extra property break everything. Is there a way with svcutil to generate the code without the Order attribute, or to make the Order attribute not be used in the deserialization process?

[rlima-caylent]

I'm getting the same error here — I had to manually remove the Order attributes to get it working.

The fields with the Order attribute are not being serialized/deserialized.

Using the [Microsoft.Tools.ServiceModel.Svcutil, Version 2.1.0]

[goyometeojorito]

I'm getting the same error here — I had to manually remove the Order attributes to get it working.

The fields with the Order attribute are not being serialized/deserialized.

Using the [Microsoft.Tools.ServiceModel.Svcutil, Version 2.1.0]

It's true that it partially works, except for one detail. Classes that have the MessageContractAttribute attribute need to have the Order attribute (those classes are used to match the function, and the order of the parameters must be the same).
But the others don't.

I've created a small script that respects this (removing the order only from the data classes and not from the classes that define method parameters), and it works correctly. Perhaps the SvcUtil utility should have some parameter to take this into account.

This is the script (it's not optimized it's for run only after update references):

var removeOrder = true;

var removeOrderRegex = new Regex(@"(, *Order *= *\d+|Order *= *\d+)", RegexOptions.Compiled);
var messageContratRegex = new Regex(@"MessageContractAttribute\(", RegexOptions.Compiled);
var xmlTypeAttribute = new Regex(@"XmlTypeAttribute\(", RegexOptions.Compiled);

var ok = false;
using (var source = new StreamReader(File.Open(sourceFilename, FileMode.Open, FileAccess.Read, FileShare.Read)))
using (var tmp = new StreamWriter(File.Open(tmpFilename, FileMode.Create, FileAccess.Write, FileShare.None), new UTF8Encoding(true)))
{
	while (true)
	{
		var line = source.ReadLine();
		if(line == null) { ok = true; break; }

		if (messageContratRegex.IsMatch(line))
		{
			removeOrder = false;
		}
		if (xmlTypeAttribute.IsMatch(line))
		{
			removeOrder = true;
		}
		
		if (removeOrder)
		{
			line = removeOrderRegex.Replace(line, string.Empty);
		}

		tmp.WriteLine(line);
	}
}

if (ok)
{
	Console.WriteLine($"Replacing file...");
	File.Delete(sourceFilename);
	File.Move(tmpFilename, sourceFilename);		
}