.NET Core 9+SoapCore：移除Action节点后参数为null问题排查

问题描述 #

我正在学习SoapCore，希望SOAP请求的Body中直接显示函数参数，不包含Action节点。代码编写看似正确，但函数参数始终返回null。使用的是.NET Core 9搭配SoapCore，相关代码、请求及响应信息如下：

服务端代码 #

builder.Services.AddSoapCore();
app.UseEndpoints(endpoints =>
{
    _ = endpoints.UseSoapEndpoint<DataContractServices>("/DataContract.asmx",
        new SoapEncoderOptions(),
        SoapSerializer.DataContractSerializer);
});

[ServiceContract(Namespace = "https://service.com/")]
public class DataContractServices
{
    [OperationContract(Name = "loginMethod")]
    public string LoginMethod(LoginRequest input)
        => $"Username: {input.Username}| Password: {input.Password}";
}

[MessageContract(IsWrapped = true, WrapperName = "LoginRequest", WrapperNamespace = "https://service.com/")]
public class LoginRequest
{
    [MessageBodyMember(Name = "username")]
    public string Username { get; set; } = string.Empty;
    [MessageBodyMember(Name = "password")]
    public string Password { get; set; } = string.Empty;
}

请求内容 #

POST http://localhost:5000/DataContract.asmx
Content-Type: text/xml; charset=utf-8
SOAPAction: https://service.com/loginMethod

<?xml version="1.0" encoding="utf-8"?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:pay="https://service.com/">
   <soapenv:Header/>
   <soapenv:Body>
      <pay:LoginRequest>
        <pay:username>myUsername</pay:username>
        <pay:password>myPassword</pay:password>
      </pay:LoginRequest>
   </soapenv:Body>
</soapenv:Envelope>

响应内容 #

<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <s:Body>
    <loginMethodResponse xmlns="https://service.com/">
      <loginMethodResult>Username: | Password:</loginMethodResult>
    </loginMethodResponse>
  </s:Body>
</s:Envelope>

问题根源 #

请求中的username和password元素通过pay前缀关联到https://service.com/命名空间，但代码中MessageBodyMember属性未指定对应命名空间，默认使用空命名空间，导致DataContractSerializer无法匹配请求中的元素，最终参数值为null。

解决方法 #

方案一：为MessageBodyMember指定命名空间 #

修改LoginRequest类的属性，给每个MessageBodyMember添加命名空间配置，与请求中的命名空间保持一致：

[MessageContract(IsWrapped = true, WrapperName = "LoginRequest", WrapperNamespace = "https://service.com/")]
public class LoginRequest
{
    [MessageBodyMember(Name = "username", Namespace = "https://service.com/")]
    public string Username { get; set; } = string.Empty;
    [MessageBodyMember(Name = "password", Namespace = "https://service.com/")]
    public string Password { get; set; } = string.Empty;
}

方案二：修改请求，移除子元素的命名空间前缀 #

如果希望参数元素不使用命名空间，调整请求XML，去掉username和password的pay前缀：

<?xml version="1.0" encoding="utf-8"?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:pay="https://service.com/">
   <soapenv:Header/>
   <soapenv:Body>
      <pay:LoginRequest>
        <username>myUsername</username>
        <password>myPassword</password>
      </pay:LoginRequest>
   </soapenv:Body>
</soapenv:Envelope>

扩展：实现Body直接显示参数（无Wrapper） #

如果要实现请求Body中直接显示参数、不包含Wrapper节点，可修改MessageContract的IsWrapped为false，同时调整代码和请求：

修改后的LoginRequest类

[MessageContract(IsWrapped = false)]
public class LoginRequest
{
    [MessageBodyMember(Name = "username", Namespace = "https://service.com/")]
    public string Username { get; set; } = string.Empty;
    [MessageBodyMember(Name = "password", Namespace = "https://service.com/")]
    public string Password { get; set; } = string.Empty;
}

对应的请求XML

<?xml version="1.0" encoding="utf-8"?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:pay="https://service.com/">
   <soapenv:Header/>
   <soapenv:Body>
        <pay:username>myUsername</pay:username>
        <pay:password>myPassword</pay:password>
   </soapenv:Body>
</soapenv:Envelope>

内容的提问来源于stack exchange，提问作者Harun