BDE API Examples (DbiRegisterCallback)

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
        {
        //Simple loop to list all modes, could be used to give used
        //to give a choice
        for counter:= 0 to pcbInfo.iCount-1 do
          showmessage(pcbInfo.acbEntry[counter].szKeyWord + #13 +
                   pcbInfo.acbEntry[counter].szHelp);
        }
        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;

Example 2: Register the cbTABLECHAGNED callback for notification when a Paradox table's data has changed

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