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Monica

•Created by Monica on 11/28/2022 in #help

❔ XML serialization woes

I'm trying to use XmlSerializer, and for some reason I can't get it to serialize an array of child elements. If I specify the name manually (in the XmlElementAttribute) it works fine, but I already specify the element name on the target type using XmlTypeAttribute. My types look something like this:

public abstract record XmlGrammarItem(
    [property: XmlAttribute("Name")]
    string Name,
    [property: XmlAttribute("Base")]
    string? Base,
    [property: XmlAttribute("Type")]
    string? Type);

[XmlType("Node")]
public sealed record NodeGrammarItem(string Name, string? Base,
    [property: XmlElement]
    XmlNodeMember[] Members)
    : XmlGrammarItem(Name, Base, Name)
{
    public NodeGrammarItem() : this(null!, null, null!) {}
}

[XmlType("Member")]
public sealed record XmlNodeMember(
    [property: XmlAttribute("Name")]
    string Name,
    [property: XmlAttribute("Type")]
    string Type,
    [property: XmlAttribute("Optional")]
    bool Optional,
    [property: XmlElement]
    XmlMemberValue[] Values)
{
    public XmlNodeMember() : this(null!, null!, false, null!) {}
}

[XmlType("Value")]
public sealed record XmlMemberValue(
    [property: XmlAttribute("Type")]
    string Type)
{
    public XmlMemberValue() : this((string)null!) {}
}

public abstract record XmlGrammarItem(
    [property: XmlAttribute("Name")]
    string Name,
    [property: XmlAttribute("Base")]
    string? Base,
    [property: XmlAttribute("Type")]
    string? Type);

[XmlType("Node")]
public sealed record NodeGrammarItem(string Name, string? Base,
    [property: XmlElement]
    XmlNodeMember[] Members)
    : XmlGrammarItem(Name, Base, Name)
{
    public NodeGrammarItem() : this(null!, null, null!) {}
}

[XmlType("Member")]
public sealed record XmlNodeMember(
    [property: XmlAttribute("Name")]
    string Name,
    [property: XmlAttribute("Type")]
    string Type,
    [property: XmlAttribute("Optional")]
    bool Optional,
    [property: XmlElement]
    XmlMemberValue[] Values)
{
    public XmlNodeMember() : this(null!, null!, false, null!) {}
}

[XmlType("Value")]
public sealed record XmlMemberValue(
    [property: XmlAttribute("Type")]
    string Type)
{
    public XmlMemberValue() : this((string)null!) {}
}

And the XML I'm trying to (de)serialize looks like this:

<Node Name="CompilationUnitSyntax">
  <Member Name="Contents" Type="StatementListSyntax" />
  <Member Name="EndOfFile" Type="EndOfFileTokenSyntax" />
</Node>

<Node Name="CompilationUnitSyntax">
  <Member Name="Contents" Type="StatementListSyntax" />
  <Member Name="EndOfFile" Type="EndOfFileTokenSyntax" />
</Node>

To validate that the serialization works, I'm currently doing this:

var serializer = new XmlSerializer(typeof(NodeGrammarItem));
var obj = (NodeGrammarItem)serializer.Deserialize(File.OpenRead("node.xml"))!;
serializer.Serialize(Console.Out, obj);

var serializer = new XmlSerializer(typeof(NodeGrammarItem));
var obj = (NodeGrammarItem)serializer.Deserialize(File.OpenRead("node.xml"))!;
serializer.Serialize(Console.Out, obj);

Is there something I'm missing in order to allow XmlSerializer to read the XmlTypeAttribute for these types, or do I have to specify the element name using XmlElementAttribute? I've not been able to find anything on the docs that would suggest otherwise.

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