Variant - TVariant

Panagiotis L. Staiko

CBuilder Developer

Mon, 24 Dec 2001 03:00:00 GMT

Variant - TVariant

I will ask about TVariant and Variant Types...

I want to pass from Client to Server some integers values...
I am trying to create a Variant (as Array of varInteger values) and pass
it to Server but
some problems occured...These problems are new since i install the
C++Builder4.
In C++Builder3 all the above works correctly..

More spesific the message that i get is that "Variant is not an
Array!!!"
The variant variable has lose it's type and has type with number "3".

I use the below code:

Client Side:
-----------------
int Bounds1[2]={0, PageHits-1};
Variant v_RecIds = VarArrayCreate(Bounds1, 1, varInteger);
for (int i=0; i<PageHits; i++)
v_RecIds.PutElement(i);
Variant Result =
ClientDM->MIDASConnection->AppServer.Exec(Function("GetResultPage") <<
v_RecIds);

Server Side
--------------------
STDMETHODIMP TABEKT_iPAC_RModuleImpl::GetResultPage(TVariant RecordIDs,
TVariant* Docs)
{
try
{
Variant V(RecordIDs);
NumRecords = V.ArrayHighBound(1); ---->Error: Variant is not an
Array!!! Why?
...
...
...
}
catch(Exception &e)
{
delete pResults;
return Error(e.Message.c_str(), IID_IABEKT_iPAC_RModule);
}
return S_OK;

Quote

};

How i solve this problem?
How is the right way for this?(and general how is the way to pass
Variants from Client to Server?)
The opposite way HAS NO PROBLEM!

Martijn Brinker

CBuilder Developer

Wed, 26 Dec 2001 03:00:00 GMT

Re:Variant - TVariant

Panagiotis L. Staikos <psta...@ekt.gr> wrote in message
news:378477EB.60B59689@ekt.gr...

Quote

> I will ask about TVariant and Variant Types...

> I want to pass from Client to Server some integers values...
> I am trying to create a Variant (as Array of varInteger values) and pass
> it to Server but
> some problems occured...These problems are new since i install the
> C++Builder4.
> In C++Builder3 all the above works correctly..

Just a wild guess,
BCB4 uses TVariant for automation params. There seems to be a bug when using
TVariant because it destroys the underlying VARIANT when TVariant goes out
of scope. This was the cause of errors in my app. I don't know if this has
anything to do with your problem but perhaps you can check the VCL code.
I only have the professionel version so I can not check it for you.

Good luck,

Martijn Brinkers

Steve Donova

CBuilder Developer

Tue, 01 Jan 2002 03:00:00 GMT

Re:Variant - TVariant

Quote

Panagiotis L. Staikos wrote in message <378477EB.60B59...@ekt.gr>...
>I want to pass from Client to Server some integers values...
>I am trying to create a Variant (as Array of varInteger values) and pass
>it to Server but some problems occured...These problems are new since i
install the
>C++Builder4. >In C++Builder3 all the above works correctly..

Well, something very similar happened to me - but in BCB 3. I have a suite
of Delphi programs which communicate via COM, and the client passes data to
the server as a variant array of byte, as recommended as the fastest way to
get binary data across the process barrier. I have now being training a
BCB 3 program to offer the same interface as the Delphi program, and tried
to use VarArrayLock() on the variant parameter. Well, it was a reference!
So I extracted the reference variant, which was an array, and successfully
called VarArrayLock(). But when I was finished with the pointer, I was
unable to call VarArrayUnlock() with the _same variant_ without being told
that 'Variant is not an array'. Very curious, since the value didn't
change.

I wonder if this has something to do with the construction/destruction
issues involved with variants? Do note that I am using VARIANT and not
TVariant or Variant.

Steve Donovan,
Mining Technology, CSIR South Africa

Redg

CBuilder Developer

Mon, 07 Jan 2002 03:00:00 GMT

Re:Variant - TVariant

I still have this problem. Did you find any workaround???

Thanks
Redgo

Panagiotis L. Staikos <psta...@ekt.gr> wrote in message
news:378477EB.60B59689@ekt.gr...

Quote

> I will ask about TVariant and Variant Types...

> I want to pass from Client to Server some integers values...
> I am trying to create a Variant (as Array of varInteger values) and pass
> it to Server but
> some problems occured...These problems are new since i install the
> C++Builder4.
> In C++Builder3 all the above works correctly..

> More spesific the message that i get is that "Variant is not an
> Array!!!"
> The variant variable has lose it's type and has type with number "3".

> I use the below code:

> Client Side:
> -----------------
> int Bounds1[2]={0, PageHits-1};
> Variant v_RecIds = VarArrayCreate(Bounds1, 1, varInteger);
> for (int i=0; i<PageHits; i++)
> v_RecIds.PutElement(i);
> Variant Result =
> ClientDM->MIDASConnection->AppServer.Exec(Function("GetResultPage") <<
> v_RecIds);

> Server Side
> --------------------
> STDMETHODIMP TABEKT_iPAC_RModuleImpl::GetResultPage(TVariant RecordIDs,
> TVariant* Docs)
> {
> try
> {
> Variant V(RecordIDs);
> NumRecords = V.ArrayHighBound(1); ---->Error: Variant is not an
> Array!!! Why?
> ...
> ...
> ...
> }
> catch(Exception &e)
> {
> delete pResults;
> return Error(e.Message.c_str(), IID_IABEKT_iPAC_RModule);
> }
> return S_OK;
> };

> How i solve this problem?
> How is the right way for this?(and general how is the way to pass
> Variants from Client to Server?)
> The opposite way HAS NO PROBLEM!

Panagiotis L. Staiko

CBuilder Developer

Sat, 12 Jan 2002 03:00:00 GMT

Re:Variant - TVariant

I did not find any solution....
i pass a AnsiString Str where Str has format (e.g 3_12_56_5) when
i should sent to server the record id's 3,12,56,5 and at the server
side i check for the underscores and i get the numbers....

In C++Builder3 this was too simple....
I hope to find a solution or if it is a bug i hope Borland fix it...

Quote

Redgo wrote:
> I still have this problem. Did you find any workaround???

> Thanks
> Redgo

> Panagiotis L. Staikos <psta...@ekt.gr> wrote in message
> news:378477EB.60B59689@ekt.gr...
> > I will ask about TVariant and Variant Types...

> > I want to pass from Client to Server some integers values...
> > I am trying to create a Variant (as Array of varInteger values) and pass
> > it to Server but
> > some problems occured...These problems are new since i install the
> > C++Builder4.
> > In C++Builder3 all the above works correctly..

> > More spesific the message that i get is that "Variant is not an
> > Array!!!"
> > The variant variable has lose it's type and has type with number "3".

> > I use the below code:

> > Client Side:
> > -----------------
> > int Bounds1[2]={0, PageHits-1};
> > Variant v_RecIds = VarArrayCreate(Bounds1, 1, varInteger);
> > for (int i=0; i<PageHits; i++)
> > v_RecIds.PutElement(i);
> > Variant Result =
> > ClientDM->MIDASConnection->AppServer.Exec(Function("GetResultPage") <<
> > v_RecIds);

> > Server Side
> > --------------------
> > STDMETHODIMP TABEKT_iPAC_RModuleImpl::GetResultPage(TVariant RecordIDs,
> > TVariant* Docs)
> > {
> > try
> > {
> > Variant V(RecordIDs);
> > NumRecords = V.ArrayHighBound(1); ---->Error: Variant is not an
> > Array!!! Why?
> > ...
> > ...
> > ...
> > }
> > catch(Exception &e)
> > {
> > delete pResults;
> > return Error(e.Message.c_str(), IID_IABEKT_iPAC_RModule);
> > }
> > return S_OK;
> > };

> > How i solve this problem?
> > How is the right way for this?(and general how is the way to pass
> > Variants from Client to Server?)
> > The opposite way HAS NO PROBLEM!

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