using System;

using System.IO;

using System.Linq;

using System.Text;

using System.Text.Json;

using System.Xml;

using System.Xml.Serialization;

​

public class Program

{

    public static void Main()

    {

        // Serialize a array as element text using XmlTextAttribute

        // e.g.: <root>1 2 3</root>

​

        // FAIL: 

        // serialization:   missing whitespace separators: <Root1>123</Root1>

        // deserialization: doesn't split on whitespace and 

        XmlElement();

​

        // OK: shadow property does splitting and joining

        ShadowProperty();

​

        // OK: alternative using attribute: <Root2 Ids="1 2 3" />

        XmlAttribute();

    }

​

    public static void XmlElement()

    {

        Console.WriteLine("Root1 string[] property with XmlTextAttribute");

        var ser = new XmlSerializer(typeof(Root1));

        var sb = new StringBuilder();

        var writer = XmlWriter.Create(sb, new XmlWriterSettings { Indent = true, OmitXmlDeclaration = true });

​

        ser.Serialize(writer, new Root1 { Ids = ["1", "2", "3"] }, new XmlSerializerNamespaces([new XmlQualifiedName("", "")]));

        Console.WriteLine($"[FAIL] serialize is missing whitespace separators: {sb}");

        // expected: <Root1>1 2 3</Root1>

        // actual:   <Root1>123</Root1>

​

        Root1 root1 = (Root1)ser.Deserialize(new StringReader("<Root1>1 2 3</Root1>"))!;

        Console.WriteLine($"[FAIL] deserialize returns only 1 squashed element instead of 3 separated: {JsonSerializer.Serialize(root1.Ids)}\n");

        // expected: 3 elements: ["1", "2", "3"]

        // actual:   1 element:  "1 2 3"

    }

​

    public static void ShadowProperty()

    {

        Console.WriteLine("Root2 workaround with shadow property for splitting and joining:");

        var ser = new XmlSerializer(typeof(Root2));

        var sb = new StringBuilder();

        var writer = XmlWriter.Create(sb, new XmlWriterSettings { Indent = true, OmitXmlDeclaration = true });

​

        ser.Serialize(writer, new Root2 { Ids = [1, 2, 3] }, new XmlSerializerNamespaces([new XmlQualifiedName("", "")]));

        Console.WriteLine($"[OK] Root2 serialize as whitespace separated list: {sb}");

        // expected: <Root2>1 2 3</Root2>

        // actual: correct

​

        // Deserialization

        var xml = "<Root2>1 2 3</Root2>";

        var stream = new StringReader(xml);

        var root2 = ser.Deserialize(stream) as Root2;

        Console.WriteLine($"[OK] Root2 deserialize has 3 elements: {JsonSerializer.Serialize(root2.Ids)}\n");

        // expected: 3 elements

        // actual: correct

    }

​

    public static void XmlAttribute()

    {

        Console.WriteLine("Root3 alternative serialization using xml attribute:");

        var ser = new XmlSerializer(typeof(Root3));

        var sb = new StringBuilder();

        var writer = XmlWriter.Create(sb, new XmlWriterSettings { Indent = true, OmitXmlDeclaration = true });

​

        ser.Serialize(writer, new Root3 { Ids = ["1", "2", "3"] }, new XmlSerializerNamespaces([new XmlQualifiedName("", "")]));

        Console.WriteLine($"[OK] serialize: {sb}");

        // expected : attribute Ids="1 2 3"

        // actual: correct

​

        var root3 = ser.Deserialize(new StringReader("""<Root3 Ids="1 2 3" />""")) as Root3;

        Console.WriteLine($"[OK] deserialize: {JsonSerializer.Serialize(root3.Ids)}\n");

        // expected: 3 elements

        // actual: correct

    }

}

​

public class Root1

{

    // The XmlTextAttribute [with type set to string] informs the XmlSerializer that strings should be serialize as XML [inner]text.

    // Unfortunately, array on elements are not supported:

    // .NET Framework https://learn.microsoft.com/en-us/previous-versions/dotnet/netframework-4.0/t84dzyst(v=vs.100) "The .NET Framework provides accurate bindings for XML attribute declarations with list types, **but not for element declarations**."

    // .NET https://learn.microsoft.com/en-us/dotnet/api/system.xml.serialization.xmltextattribute

    [XmlText]

    public string[] Ids;

}

​

public partial class Root2

{

    [XmlText]

    public string Value;

}

​

public partial class Root2

{

    [XmlIgnore]

    public int[] Ids

    {

        get => Value.Split(" ").Where(v => !string.IsNullOrWhiteSpace(v)).Select(int.Parse).ToArray();

        set => Value = string.Join(" ", value);

    }

}

​

public class Root3

{

    [XmlAttribute]

    public string[] Ids;

}