C# 为什么可以'；我不能把这个对象作为参数传递吗？

背景：

使用.NET4.0在C#中编写使用web服务的客户端。代理类包括一个record类型的对象，该对象由web服务的SOAP响应填充

情况：

该API包括两个函数，

findRecords

和

getRecords

。这两个函数都下载实际记录，区别在于

findRecords

的类型为void并通过out参数提供记录，而

getRecords

的类型为record，因此返回记录

问题:

执行对

findRecords

的调用后，我可以访问记录对象的成员（如

recordID

，

recordTitle

等），以便在其他函数参数中使用。但是，如果尝试将记录对象本身作为参数传递，则会得到

ArgumentNullException

。当前唯一可以将记录作为参数传递的方法是使用从

getRecords

函数返回的记录。这种方法的缺点是，它使我需要进行的API调用数量增加了一倍，这会降低我的客户端和web服务的速度

问题:

为什么它会这样，我可以做些什么来将记录对象作为参数从

findRecords

传递过来

代码：

这是findRecords函数的定义：

    [System.Web.Services.Protocols.SoapDocumentMethodAttribute("http://localhost:8080/findRecords", RequestNamespace="http://www.<redacted>.com/ws/schemas", ResponseNamespace="http://www.<redacted>.com/ws/schemas", Use=System.Web.Services.Description.SoapBindingUse.Literal, ParameterStyle=System.Web.Services.Protocols.SoapParameterStyle.Wrapped)]
    public void findRecords([System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=true)] string username, [System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=true)] filter filter, [System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified, DataType="integer")] string offset, [System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified, DataType="integer")] string count, [System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=true)] out System.Nullable<int> numResults, [System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=true)] [System.Xml.Serialization.XmlIgnoreAttribute()] out bool numResultsSpecified, [System.Xml.Serialization.XmlArrayAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=true)] [System.Xml.Serialization.XmlArrayItemAttribute("list", Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=false)] out record[] results) {
        object[] results1 = this.Invoke("findRecords", new object[] {
                    username,
                    filter,
                    offset,
                    count});
        numResults = ((System.Nullable<int>)(results1[0]));
        numResultsSpecified = ((bool)(results1[1]));
        results = ((record[])(results1[2]));
    }

    [System.Web.Services.Protocols.SoapDocumentMethodAttribute("http://localhost:8080/getRecords", RequestNamespace="http://www.<redacted>.com/ws/schemas", ResponseNamespace="http://www.<redacted>.com/ws/schemas", Use=System.Web.Services.Description.SoapBindingUse.Literal, ParameterStyle=System.Web.Services.Protocols.SoapParameterStyle.Wrapped)]
    [return: System.Xml.Serialization.XmlArrayAttribute("records", Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=true)]
    [return: System.Xml.Serialization.XmlArrayItemAttribute("list", Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=false)]
    public record[] getRecords([System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=true)] string username, [System.Xml.Serialization.XmlArrayAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=true)] [System.Xml.Serialization.XmlArrayItemAttribute("list", Form=System.Xml.Schema.XmlSchemaForm.Unqualified, DataType="integer", IsNullable=false)] string[] stiIds) {
        object[] results = this.Invoke("getRecords", new object[] {
                    username,
                    recordIds});
        return ((record[])(results[0]));
    }

[System.Web.Services.Protocols.SoapDocumentMethodAttribute（“http://localhost:8080/findRecords，RequestNamespace=http://www..com/ws/schemas，ResponseNamespace=http://www..com/ws/schemas，Use=System.Web.Services.Description.SoapBindingUse.Literal，ParameterStyle=System.Web.Services.Protocols.SoapParameterStyle.Wrapped）]
public void findRecords（[System.Xml.Serialization.XmlElementAttribute（Form=System.Xml.Schema.XmlSchemaForm.Unqualified，IsNullable=true）]字符串用户名，[System.Xml.Serialization.XmlElementAttribute（Form=System.Xml.Schema.XmlSchemaForm.Unqualified，IsNullable=true）]筛选器，[System.Xml.Serialization.XmlElementAttribute（Form=System.Xml.Schema.XmlSchemaForm.Unqualified，DataType=“integer”）]字符串偏移量，[System.Xml.Serialization.xmlementAttribute（Form=System.Xml.Schema.XmlSchemaForm.Unqualified，DataType=“integer”）]字符串计数，[System.Xml.Serialization.xmlementAttribute（Form=System.Xml.Schema.XmlSchemaForm.Unqualified，IsNullable=true）]out System.Nullable numResults[System.Xml.Serialization.xmlementAttribute（Form=System.Xml.Schema.XmlSchemaForm.Unqualified，IsNullable=true）][System.Xml.Serialization.XmlIgnoreAttribute（）]out bool numResults指定的[System.Xml.Serialization.XmlArrayAttribute（Form=System.Xml.Schema.XmlSchemaForm.Unqualified，IsNullable=true）][System.Xml.Serialization.XmlArrayItemAttribute（“list”，Form=System.Xml.Schema.XmlSchemaForm.Unqualified，IsNullable=false）]输出记录[]结果）{
object[]results1=this.Invoke（“findRecords”，新对象[]{
用户名，
过滤器，
抵消，
计数}）；
numResults=（（System.Nullable）（results1[0]）；
numResultsSpecified=（（bool）（结果1[1]）；
结果=（（记录[]）（结果1[2]）；
}

getRecords函数的定义：

    [System.Web.Services.Protocols.SoapDocumentMethodAttribute("http://localhost:8080/findRecords", RequestNamespace="http://www.<redacted>.com/ws/schemas", ResponseNamespace="http://www.<redacted>.com/ws/schemas", Use=System.Web.Services.Description.SoapBindingUse.Literal, ParameterStyle=System.Web.Services.Protocols.SoapParameterStyle.Wrapped)]
    public void findRecords([System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=true)] string username, [System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=true)] filter filter, [System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified, DataType="integer")] string offset, [System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified, DataType="integer")] string count, [System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=true)] out System.Nullable<int> numResults, [System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=true)] [System.Xml.Serialization.XmlIgnoreAttribute()] out bool numResultsSpecified, [System.Xml.Serialization.XmlArrayAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=true)] [System.Xml.Serialization.XmlArrayItemAttribute("list", Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=false)] out record[] results) {
        object[] results1 = this.Invoke("findRecords", new object[] {
                    username,
                    filter,
                    offset,
                    count});
        numResults = ((System.Nullable<int>)(results1[0]));
        numResultsSpecified = ((bool)(results1[1]));
        results = ((record[])(results1[2]));
    }

    [System.Web.Services.Protocols.SoapDocumentMethodAttribute("http://localhost:8080/getRecords", RequestNamespace="http://www.<redacted>.com/ws/schemas", ResponseNamespace="http://www.<redacted>.com/ws/schemas", Use=System.Web.Services.Description.SoapBindingUse.Literal, ParameterStyle=System.Web.Services.Protocols.SoapParameterStyle.Wrapped)]
    [return: System.Xml.Serialization.XmlArrayAttribute("records", Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=true)]
    [return: System.Xml.Serialization.XmlArrayItemAttribute("list", Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=false)]
    public record[] getRecords([System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=true)] string username, [System.Xml.Serialization.XmlArrayAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=true)] [System.Xml.Serialization.XmlArrayItemAttribute("list", Form=System.Xml.Schema.XmlSchemaForm.Unqualified, DataType="integer", IsNullable=false)] string[] stiIds) {
        object[] results = this.Invoke("getRecords", new object[] {
                    username,
                    recordIds});
        return ((record[])(results[0]));
    }

[System.Web.Services.Protocols.SoapDocumentMethodAttribute（“http://localhost:8080/getRecords，RequestNamespace=http://www..com/ws/schemas，ResponseNamespace=http://www..com/ws/schemas，Use=System.Web.Services.Description.SoapBindingUse.Literal，ParameterStyle=System.Web.Services.Protocols.SoapParameterStyle.Wrapped）]
[返回：System.Xml.Serialization.XmlArrayAttribute（“记录”，Form=System.Xml.Schema.XmlSchemaForm.Unqualified，IsNullable=true）]
[返回：System.Xml.Serialization.XmlArrayItemAttribute（“list”，Form=System.Xml.Schema.XmlSchemaForm.Unqualified，IsNullable=false）]
公共记录[]getRecords（[System.Xml.Serialization.XmlElementAttribute（Form=System.Xml.Schema.XmlSchemaForm.Unqualified，IsNullable=true）]字符串用户名，[System.Xml.Serialization.XmlArrayAttribute（Form=System.Xml.Schema.XmlSchemaForm.Unqualified，IsNullable=true）][System.Xml.Serialization.XmlArrayItemAttribute（“列表”，Form=System.Xml.Schema.XmlSchemaForm.Unqualified，DataType=“integer”，IsNullable=false）]字符串[]stiid）{
object[]results=this.Invoke（“getRecords”，新对象[]{
用户名，
记录ID}）；
返回（（记录[]）（结果[0]）；
}

我想用它做什么：

        // Objects to use for the findRecords call
        int? numResults;
        bool numResultsSpecified;
        record[] records;

        // Object for handling and saving the XML
        XRecord r;

                try
                {
                    ws.findRecords(usernames[uname_Index], GetFilter(), offset.ToString(), count.ToString(),
                        out numResults, out numResultsSpecified, out returnRecords);

                    for (int i = 0; i < returnRecords.Length; i++)
                    {
                        count--;
                        r = GrabRecord(returnRecords[i]);
                        r.record.Save(@".\Records\" + r.id + "_" + r.date2 + ".xml");
                    }
                }

//用于findRecords调用的对象
int？numResults；
指定的布尔数结果；
记录[]项记录；
//对象来处理和保存XML
xr；
尝试
{
ws.findRecords（用户名[uname_Index]、GetFilter（）、offset.ToString（）、count.ToString（），
out numResults、out numResults specified、out return records）；
for（int i=0；i

    private static XRecord GrabRecord(record _record)
    {
        XNamespace nameSpace = "http://www.<redacted>.com/ws/schemas";

        XDocument r =
            new XDocument(
                new XElement(nameSpace + "getRecordsResponse",
                    new XAttribute(XNamespace.Xmlns + "ns1", nameSpace),
                    new XElement("list",
                        new XElement("ID", _record.id),
                        new XElement("title", _record.title),
            ...............
                        new XElement("comments", _record.comments),
                        new XElement("category", _record.category),
                        _record.modifiedDateSpecified ? new XElement("modifiedDate", _record.modifiedDate) : null,
                        new XElement("attachments", from a in _record.attachments
                                                    select new XElement("list",
                                                        new XElement("id", a.id),
                                                        new XElement("filePath", a.filePath),
                                                        new XElement("type", a.type))));

        XRecord xr = new XRecord();
        xr.record = r;
        xr.id = _record.id;
        xr.date2 = ConvertToDateString(_record.modifiedDate);

        return xr;
    }

私有静态XRecord GrabRecord（记录_记录）
{
XNamespace名称空间=”http://www..com/ws/schemas";
XDocument r=
新XDocument(
新XElement（命名空间+“getRecordsResponse”，
新的XAttribute（XNamespace.Xmlns+“ns1”，名称空间），
新XElement（“列表”，
新的元素（“ID”、_record.ID），
新XElement（“标题”，“记录标题”），
...............
新的元素（“注释”、_record.comments），
新元素（“类别”