如何将包含UDT的SAFEARRAY的IDL结构编组为托管代码

Question

I have a COM library defined with this IDL code:

struct T_GPSParamsMap
{
  BSTR  Key;
  BSTR  Value;    
}T_GPSParamsMap;


struct T_FwClient
{
  BSTR                      Alias;
  SMSFilterActionEnum       Action;
  BSTR                      Text;
  int                       ToCall;
  int                       ToState;
  SAFEARRAY(T_GPSParamsMap) GpsData;
} T_FwClient;


struct T_SMSAction
{
  int                       ActionID;
  SMSFilterActionEnum       Action;
  BSTR                      Text;
  BSTR                      Folder;
  BSTR                      DestAddress;
  int                       ToCall;
  int                       ToState;
  SAFEARRAY(T_GPSParamsMap) GpsData;

  VARIANT_BOOL          forwardToNotListed;
  SAFEARRAY(T_FwClient) FwClients;

} T_SMSAction;

[
object,
uuid(F7942BCA-5122-46BB-94DB-89F5071842E4),
dual,
oleautomation,
nonextensible,
helpstring("ISMSFilter Interface"),
pointer_default(unique)
]
interface ISMSFilterWrapper : IDispatch{
  [id(1), helpstring("method GetFilterResult")] 
  HRESULT Init([in] BSTR schema_file_path, [out, retval] long* pVal);

  [id(2), helpstring("method GetFilterResult")] 
  HRESULT ApplyFilter([in] T_SMS* sms, [out, retval] long* pVal);

  [id(3), helpstring("method GetFilterResult")] 
  HRESULT GetFilterResult([in, out] T_SMSAction* ret_val, [out, retval] long* pVal);
};

Now, I use it in c# in this way:

SMSFilterLib.T_SMS smsFilter = new SMSFilterLib.T_SMS();
SMSFilterLib.T_SMSAction smsRule = new SMSFilterLib.T_SMSAction();

smsFilter.CalledParty = Convert.ToString(RadioID);
smsFilter.CallingParty = "1";
smsFilter.Text = Text;

m_smsFilter.ApplyFilter(ref smsFilter);

int RV = m_smsFilter.GetFilterResult(ref smsRule);

The last line raise an exception (translated from italian):

HResult = -2146233054

first-chance exception of type 'System.TypeLoadException' Unable to marshal the filed GpsData of type 'SMSFilterLib.T_SMSAction': no support of marshaling available for this type.

This COM library is used in old VB6 application and works well..

I've imported it in c# using the standard CCW of Visual studio (adding it through references) but maybe it need to have a custom CCW.

Can someone give me some suggestions how to use it?

Regards, Daniele

Answer 1

Instead to add the COM reference with the Visual Studio "Add Reference Windows", create an interop assembly with tlbimp.exe

When a COM library is added through Visual Studio, it create its definition via tlbimp passing to it the switch /sysarray which "Import SAFEARRAY as System.Array".

Instead of using VS, use tlbimp by hand without to pass that switch:

tlbimp.exe COM_DLL_NAME.dll /out:INTEROP_ASSEMBLY_NAME.dll

and it will creates specialized typed arrays:

  [Guid("4162E179-7E99-4783-95D9-DA9A0B3BE568")]
  public struct T_SMSAction
  {
    public SMSFilterActionEnum Action;
    public int ActionID;
    public string DestAddress;
    public string Folder;
    public short forwardToNotListed;
    public T_FwClient[] FwClients;
    public T_GPSParamsMap[] GpsData;
    public string Text;
    public int ToCall;
    public int ToState;
  }

Regards.