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Randel Bjorkquist · Guest

Hello all,

I need some help understanding why I get the following errors, "Can not
assign TQuery to TQuery" and "Can not assign TDataSource to TDataSource"
when I use the "TPersistent::Assign", as shown below as
tQuery->Assign(TmpQuery) or tDataSource->Assign(TmpSource). I use my base
class, TBaseData, when I create my other classes, like: Audit, AuditType,
Plant, Employee, etc...

In my base class, I have TQuery and TDataSource pointer pointing to their
respective components in a TDataModule. My inherited classes work fine if I
have only created one of those objects, like in my plant form. In my plant
form, the form's OnShow event creates a new TPlant object and the OnClose
event, deletes it. But if I try to have two or more objects in memory, I
run into problems with my TQuery & TDataSource pointers. So what I'm trying
to do is to change from pointing to the components in the TDataModule, but
still use them as a kind of template to creating new TQuery & TDataSource
components for each new instance of my objects.

If I'm mistaken and I can not use the "Assign" method, does anyone have any
other ideas how to do what I'm trying?

Thanks for any and all help in advance,

Randel Bjorkquist

//--------------------------------------------------------------------------
-
void __fastcall TBaseData::Set_DataModule(TDataModule* tModule)
{
:
Get_TQuery(FQuery, "qry_" + dmShortName);
Get_TDataSource(FDataSource, "ds_" + dmShortName);
:
}//end of "TBaseData::Set_DataModule()" method

//--------------------------------------------------------------------------
-
__fastcall TBaseData::TBaseData(void)
{
FQuery = new TQuery(NULL);
FDataSource = new TDataSource(NULL);
}//end of "TBaseData::TBaseData()" method

//--------------------------------------------------------------------------
-
__fastcall TBaseData::~TBaseData(void)
{
delete FQuery;
delete FDataSource;
}//end of "TBaseData::~TBaseData()" method

//--------------------------------------------------------------------------
-
TComponent* __fastcall TBaseData::Get_TComponent(AnsiString tName)
{
TComponent* TmpComponent = NULL;

for(int i = 0; i < FDataModule->ComponentCount; i++){
if(FDataModule->Components[i]->Name == tName){
TmpComponent = FDataModule->Components[i];
break;
}//end of "if-statement"
}//end of "for-loop

return(TmpComponent);
}//end of "TBaseData::Get_TComponent" method

//--------------------------------------------------------------------------
-
void __fastcall TBaseData::Get_TQuery(TQuery* tQuery, AnsiString tName)
{
TQuery* TmpQuery = new TQuery(NULL);
TmpQuery = dynamic_cast<TQuery*> (Get_TComponent(tName));

//THIS CAUSES THE ERROR "Can not assign TQuery to TQuery"
//***************************************************
tQuery->Assign(TmpQuery);
//***************************************************

delete TmpQuery;
TmpQuery = NULL;
}//end of "TBaseData::Get_TQuery()" method

//--------------------------------------------------------------------------
-
void __fastcall TBaseData::Get_TDataSource(TDataSource* tDataSource,
AnsiString tName)
{
TDataSource* TmpSource = new TDataSource(NULL);
TmpSource = dynamic_cast<TDataSource*> (Get_TComponent(tName));

//THIS CAUSES THE ERROR "Can not assign TDataSource to TDataSource"
//***********************************************************
tDataSource->Assign(TmpSource);
//***********************************************************

delete TmpSource;
TmpSource = NULL;
}//end of "TBaseData::Get_TDataSource()" method

Todd Brylski · Guest

"Randel Bjorkquist" <rbjorkquist (AT) coilcraft (DOT) com> wrote

Randel Bjorkquist · Guest

Hey Todd,

Thanks for your reply. I see what you are talking about, and honestly don't
know why I did it that way to begin with. But, I am still trying to find a
way in which I can make a duplicate TQuery or TDataSource component from an
existing one.

What I was hoping to be able to do was take a TDataModule, place all the
general components I wanted on it and be able to "copy" it, kind of use it
like a template (not a C++ Template, but more like a Microsoft Word/Excel
template). So I was hoping to be able to create a function in which I could
pass it the name of a TQuery or TDataSource and have it return a pointer to
the new "copy" / duplicate.

Thanks again and if you have any other ideas, please feel free to let me
know.

Randel

"Todd Brylski" <tbrylski (AT) yyaahhoooo (DOT) com> wrote

Todd Brylski · Guest

"Randel Bjorkquist" <rbjorkquist (AT) coilcraft (DOT) com> wrote