使用SoapCore时WSDL中缺失DerivedClass，该如何解决？

要让DerivedClass出现在WSDL中，你需要在服务契约接口上也添加[XmlInclude(typeof(DerivedClass))]，仅在基类上添加该特性不足以让SoapCore的WSDL生成器识别到派生类型。

具体修改方案 #

有两种添加方式：

1. 在单个操作契约上添加

[ServiceContract(Namespace = "http://example.org/")]
public interface ITesting
{
    [OperationContract]
    [XmlInclude(typeof(DerivedClass))] // 新增此特性
    public BaseClass Test(BaseClass someObj);
}

2. 在整个服务契约接口上添加（适用于多个操作都涉及该派生类的场景）

[ServiceContract(Namespace = "http://example.org/")]
[XmlInclude(typeof(DerivedClass))] // 新增此特性
public interface ITesting
{
    [OperationContract]
    public BaseClass Test(BaseClass someObj);
}

原因说明 #

SoapCore使用XmlSerializer生成WSDL时，元数据是基于服务契约（ITesting接口）的定义来生成的。虽然基类上的[XmlInclude]能让序列化器在运行时处理派生类，但WSDL生成器需要在契约层面明确感知到这些类型，才能将它们包含到WSDL的类型定义中。

修改后的完整代码示例 #

using SoapCore;
using System.ServiceModel;
using System.Xml.Serialization;

internal class Program
{
    private static void Main(string[] args)
    {
        var builder = WebApplication.CreateBuilder(args);

        builder.Services.AddControllers().AddXmlSerializerFormatters();
        builder.Services.AddSoapCore();
        builder.Services.AddScoped<ITesting, Testing>();

        var app = builder.Build();

        app.UseHttpsRedirection();
        app.UseRouting();
        app.UseAuthorization();
        app.UseEndpoints(endpoints => { 
            endpoints.UseSoapEndpoint<ITesting>("/Testing", 
                new SoapEncoderOptions(), SoapSerializer.XmlSerializer);
        });
        app.MapControllers();
        app.Run();
    }
}

public class Testing : ITesting
{
    private IWebHostEnvironment Environment;

    public Testing(IWebHostEnvironment _environment)
    {
        Environment = _environment;
    }

    public BaseClass Test(BaseClass someObj)
    {
        throw new NotImplementedException();
    }
}

[ServiceContract(Namespace = "http://example.org/")]
[XmlInclude(typeof(DerivedClass))] // 服务契约级别添加XmlInclude
public interface ITesting
{
    [OperationContract]
    public BaseClass Test(BaseClass someObj);
}

[Serializable]
public class DerivedClass : BaseClass
{
    [XmlElement]
    public string DerivedProp { get; set; }
}

[Serializable]
[XmlInclude(typeof(DerivedClass))]
public class BaseClass
{
    [XmlElement]
    public string BaseProp { get; set; }
}

内容的提问来源于stack exchange，提问作者Dialecticus