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Example 1: Create a callback that handles the condition of a missing .MDX file for a dBASE file or a missing .CDX file for a FoxPro file:

 

//Function called by DbiRegisterCallBack

function myfunc(ecbType : CBType; iClientData : LongInt;

 pCbInfo : pCBInputDesc): CBRType; stdcall;

const

 READONLY = 'Read Only';

 FAILOPEN = 'Fail Open';  //The default

 OPENANDDETACH = 'Open and Detach';

var

 counter : Integer;

begin

case ecbtype of

   cbINPUTREQ:  //It's a callback of cbINPUTREQ type

    if (pcbInfo.eCbInputId = cbiMDXMIssing) then begin

      for counter:=0 to (pcbInfo.iCount – 1) do

        if (pcbInfo.acbEntry[counter].szKeyword = OPENANDDETACH) then begin

           pcbInfo.iSelection := counter + 1;

           pcbInfo.bSave := False;

           break;

        end;

    end

    else //if

       ShowMessage('Unexpected eCbInputId');

else  //case

   ShowMessage('Unexpected ecbType')

end;

end;

//Register the callback and open the table

procedure TForm1.Button2Click(Sender: TObject);

var

 cbinfo : CBInputDesc;

begin

 Session.Open;

 Check(DbiRegisterCallBack(

  nil,                         //Cursor (Optional)

   cbINPUTREQ,                  //Type of Callback

   LongInt(0),                  //Pass-through client data

   sizeof(CBInputDesc),         //Callback buffer len

   cbinfo,                      //Pointer to callback function

   @myfunc                      //Call back fn being registered

   ));

 Table1.Open;

 //Unregister the callback

 Check(DbiRegisterCallBack(nil, cbINPUTREQ, 0,

   sizeof(CBInputDesc), nil , nil));

end;