ADODB.Stream objects and Variants

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5 total messages Started by Russell Allen Fri, 16 Sep 2005 11:00

#587

Author: Russell Allen
Date: Fri, 16 Sep 2005 11:00

17 lines
1507 bytes

Hi all,

I'm working on CBuilder 5 without ADO controls, so I'm currently using Variants to access ADO.  How can I get the following code (or something like it) to work?

void putStream (TMemoryStream *memStream) {
  Variant stream = CreateOleObject("ADODB.Stream");
  stream.OleProcedure("Open");
  stream.OleProcedure("Write", memStream);
}

I know the above code doesn't appear to do anything, but I've got code I've left out which then goes on to do something with the stream Variant.

Thanks all,

Russ
Russell Allen

Re: ADODB.Stream objects and Variants

#588

Author: Viatcheslav V. Vassiliev
Date: Fri, 16 Sep 2005 20:40

37 lines
2294 bytes

You can:
- wrap stream using TOleStream (ADODB.Stream implements IStream);
- wrap your memStream with TStreamAdapter and use it instead of ADODB.Stream 
(when you pass stream, pass Variant of type IUnknown and value should have 
interface that can be queried for IStream, IStream is implemented in 
TStreamAdapter).

//------------------------------------------
Regards,
Vassiliev V. V.
http://www.managed-vcl.com - using .Net objects in Delphi for Win32 + 
ADO.Net
http://www.oledbdirect.com - The fastest way to access MS SQL Server,
MS Jet (Access) and Interbase (through OLEDB)

"Russell Allen" <russell.allen@bt.com> �������/�������� � �������� 
���������: news:432aa5ea$1@newsgroups.borland.com...
>
> Hi all,
>
> I'm working on CBuilder 5 without ADO controls, so I'm currently using 
> Variants to access ADO.  How can I get the following code (or something 
> like it) to work?
>
> void putStream (TMemoryStream *memStream) {
>  Variant stream = CreateOleObject("ADODB.Stream");
>  stream.OleProcedure("Open");
>  stream.OleProcedure("Write", memStream);
> }
>
> I know the above code doesn't appear to do anything, but I've got code 
> I've left out which then goes on to do something with the stream Variant.
>
> Thanks all,
>
> Russ
> Russell Allen

Re: ADODB.Stream objects and Variants

#589

Author: Mark Guerrieri
Date: Fri, 16 Sep 2005 22:37

48 lines
1909 bytes

Import the ADO type library and include the resulting import file, i.e.

#include "AdoDb_TLB.H"

Then you can do this:

void putStream (TMemoryStream *memStream)
{
  StreamPtr pStream = CoStream::Create();
  OLECHECK(pStream->Open( {appropriate open parameters} ));

  memStream->Seek(0, soFromBeginning);
  bool FReleaseStream = true;
  TStreamAdapter *sa = new TStreamAdapter(memStream, soReference);
  if(!sa)
    throw Exception("Could not create Stream interface");
  try
  {
    IUnknown* iunk = NULL;
    try
    {
      OLECHECK(sa->QueryInterface(IID_IUnknown, (LPVOID*)&iunk));
      if(iunk == NULL)
        throw Exception("Stream interface does not implement the IUnknown
interface");

      TVariant v = iunk;

      OLECHECK2(pStream->Write(v));
    }
    __finally
    {
      if(iunk)
      {
        FReleaseStream = false;
        iunk->Release();
      }
    }
  }
  __finally
  {
    if(FReleaseStream && sa)
      delete sa;
  }
}


Mark

Re: ADODB.Stream objects and Variants

#590

Author: Viatcheslav V. Vassiliev
Date: Sat, 17 Sep 2005 10:02

67 lines
2598 bytes

You can use

TVariant v = iunk;

instead of pStream and pass it to ADO. This will remove a need to have 
second stream.

//------------------------------------------
Regards,
Vassiliev V. V.
http://www.managed-vcl.com - using .Net objects in Delphi for Win32 + 
ADO.Net
http://www.oledbdirect.com - The fastest way to access MS SQL Server,
MS Jet (Access) and Interbase (through OLEDB)

"Mark Guerrieri" <mguerrieri@nospam_cmsgrp.com> �������/�������� � �������� 
���������: news:432b48dd$1@newsgroups.borland.com...
> Import the ADO type library and include the resulting import file, i.e.
>
> #include "AdoDb_TLB.H"
>
> Then you can do this:
>
> void putStream (TMemoryStream *memStream)
> {
>  StreamPtr pStream = CoStream::Create();
>  OLECHECK(pStream->Open( {appropriate open parameters} ));
>
>  memStream->Seek(0, soFromBeginning);
>  bool FReleaseStream = true;
>  TStreamAdapter *sa = new TStreamAdapter(memStream, soReference);
>  if(!sa)
>    throw Exception("Could not create Stream interface");
>  try
>  {
>    IUnknown* iunk = NULL;
>    try
>    {
>      OLECHECK(sa->QueryInterface(IID_IUnknown, (LPVOID*)&iunk));
>      if(iunk == NULL)
>        throw Exception("Stream interface does not implement the IUnknown
> interface");
>
>      TVariant v = iunk;
>
>      OLECHECK2(pStream->Write(v));
>    }
>    __finally
>    {
>      if(iunk)
>      {
>        FReleaseStream = false;
>        iunk->Release();
>      }
>    }
>  }
>  __finally
>  {
>    if(FReleaseStream && sa)
>      delete sa;
>  }
> }
>
>
> Mark
>
>

Re: ADODB.Stream objects and Variants

#594

Author: Russell Allen
Date: Fri, 23 Sep 2005 11:11

77 lines
3048 bytes

Thanks guys,

This looks like exactly what I was after!  Very much appreciated.  :)

Russ

"Viatcheslav V. Vassiliev" <support@oledbdirect.com> wrote:
>You can use
>
>TVariant v = iunk;
>
>instead of pStream and pass it to ADO. This will remove a need to have 
>second stream.
>
>//------------------------------------------
>Regards,
>Vassiliev V. V.
>http://www.managed-vcl.com - using .Net objects in Delphi for Win32 + 
>ADO.Net
>http://www.oledbdirect.com - The fastest way to access MS SQL Server,
>MS Jet (Access) and Interbase (through OLEDB)
>
>"Mark Guerrieri" <mguerrieri@nospam_cmsgrp.com> �������/�������� � �������� 
>���������: news:432b48dd$1@newsgroups.borland.com...
>> Import the ADO type library and include the resulting import file, i.e.
>>
>> #include "AdoDb_TLB.H"
>>
>> Then you can do this:
>>
>> void putStream (TMemoryStream *memStream)
>> {
>>  StreamPtr pStream = CoStream::Create();
>>  OLECHECK(pStream->Open( {appropriate open parameters} ));
>>
>>  memStream->Seek(0, soFromBeginning);
>>  bool FReleaseStream = true;
>>  TStreamAdapter *sa = new TStreamAdapter(memStream, soReference);
>>  if(!sa)
>>    throw Exception("Could not create Stream interface");
>>  try
>>  {
>>    IUnknown* iunk = NULL;
>>    try
>>    {
>>      OLECHECK(sa->QueryInterface(IID_IUnknown, (LPVOID*)&iunk));
>>      if(iunk == NULL)
>>        throw Exception("Stream interface does not implement the IUnknown
>> interface");
>>
>>      TVariant v = iunk;
>>
>>      OLECHECK2(pStream->Write(v));
>>    }
>>    __finally
>>    {
>>      if(iunk)
>>      {
>>        FReleaseStream = false;
>>        iunk->Release();
>>      }
>>    }
>>  }
>>  __finally
>>  {
>>    if(FReleaseStream && sa)
>>      delete sa;
>>  }
>> }
>>
>>
>> Mark
>>
>> 
>
>

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