C# 设置一个；“可为空”；.NET对象上的属性

我有一些.NET互操作代码，我已经设法加载对象并读取属性，但是在设置对象的属性时遇到了问题。以下是Delphi代码的相关部分：

uses
  mscorlib_TLB, Winapi.ActiveX;

type
  // Irrelevant parts of the code omitted
  TDotNetObject = class(TObject)
  private
    FTarget: OleVariant;
    FType: _Type;
  public
    procedure SetProperty(const APropertyName: string; const AValue: OleVariant; const AIndex: Integer = -1);
  end;

function VariantToPSafeArray(const AValue: Variant): PSafeArray;
begin
  Result := PSafeArray(VarArrayAsPSafeArray(AValue));
end;

procedure TDotNetObject.SetProperty(const APropertyName: string; const AValue: OleVariant; const AIndex: Integer = -1);
var
  LPropertyInfo: _PropertyInfo;
  LIndex: PSafeArray;
begin
  if AIndex >= 0 then
    LIndex := VariantToPSafeArray(VarArrayOf([AIndex]))
  else
    LIndex := nil;
  LPropertyInfo := FType.GetProperty(APropertyName, BindingFlags_Instance or BindingFlags_Public or BindingFlags_NonPublic);
  if LPropertyInfo <> nil then
    LPropertyInfo.SetValue(FTarget, AValue, LIndex);
end;

procedure UpdateDefectStatus(const ADefectID, AStatus: Integer);
var
  LObject: TDotNetObject;
begin
  // ** Code to obtain the object omitted ***
  LObject.SetProperty('Status', AStatus);
end;

C#对象上的DefectStatus属性声明为：

public DefectStatus? Status

（即，它可以为空）

声明了C#中的状态属性类型：

public enum DefectStatus
{
    /// <summary>
    /// Defect Reported.
    /// </summary>
    Reported,
    /// <summary>
    /// Defect assessed.
    /// </summary>
    Assessed,
    /// <summary>
    /// Defect on work order.
    /// </summary>
    OnWorkOrder,
    /// <summary>
    /// Defect closed.
    /// </summary>
    Closed
}

---

这段代码的目标只是调用枚举类型的ToObject方法。获取LType和LDEECTSTATUSTYPE成功，但是调用InvokeMember_2没有成功，返回代码为：0x80131512，这显然是缺少的成员异常。有没有关于我做错了什么的想法？

问题是枚举不是int，这意味着

SetValue（）

需要执行双重转换（

Int32

到

DefectStatus

和

DefectStatus

到

DefectStatus？

），但它不能（它只能执行一次）

下面是一个C#代码，它复制了您试图执行的操作：

using System;
using System.Reflection;

public enum DefectStatus
{
    Reported,
    Assessed,
    OnWorkOrder,
    Closed
}

public class Defect
{
    public DefectStatus? Status {get; set;}
}

public class Test
{
    public static void Main()
    {
        Defect def = new Defect();

        PropertyInfo pi = typeof(Defect).GetProperty("Status");

        // This throws an ArgumentException
//      pi.SetValue(def, 1, null);

        // Retrieve the Assessed enum via its numeric value
        object assessed = Enum.ToObject(typeof(DefectStatus), 1);

        // This works as expected
        pi.SetValue(def, assessed, null);

        Console.WriteLine(def.Status);
    }
}

---

因此，您需要在Delphi中检索枚举。为此，您需要使用API访问

Enum

类型并在其上调用

ToObject

。

您是否有可能修改C代码？不幸的是，没有。您如何准确地进行互操作？类

\u Type

和

\u PropertyInfo

来自哪里？@Olivier他们来自mscorlib\u TLB单元，在这里：可能添加一个

绑定标志\u Public

？谢谢提示。请查看问题中我的编辑

procedure InvokeToObject;
var
  LType, LDefectStatusType: _Type;
  LInvokeFlags: TOleEnum;
  LArgs: PSafeArray;
  LValue: Integer;
  LResult: OleVariant;
  LRes: HRESULT;
  LResHex: string;
begin
  LType := MTDataClr.GetCoreType('System.Enum');
  LDefectStatusType := MTDataClr.GetType('MTData.Transport.Tracking.DefectReporting.DefectStatus');
  LInvokeFlags := BindingFlags_InvokeMethod or BindingFlags_Static;
  LValue := 1;
  LArgs := VariantToPSafeArray(VarArrayOf([LDefectStatusType, LValue]));
  LRes := LType.InvokeMember_2('ToObject', LInvokeFlags, nil, Null, LArgs, nil, LResult);
  LResHex := IntToHex(LRes);
end;

using System;
using System.Reflection;

public enum DefectStatus
{
    Reported,
    Assessed,
    OnWorkOrder,
    Closed
}

public class Defect
{
    public DefectStatus? Status {get; set;}
}

public class Test
{
    public static void Main()
    {
        Defect def = new Defect();

        PropertyInfo pi = typeof(Defect).GetProperty("Status");

        // This throws an ArgumentException
//      pi.SetValue(def, 1, null);

        // Retrieve the Assessed enum via its numeric value
        object assessed = Enum.ToObject(typeof(DefectStatus), 1);

        // This works as expected
        pi.SetValue(def, assessed, null);

        Console.WriteLine(def.Status);
    }
}