Setting TFDConnection to MongoDB

Question

In the empty project after you open TFDConnection->Open() the connection to Mongodb upon completion of the program crashes error 'Bluetooth: unable to clean up Winsock'.

Answer 1

This error appears to occur during the TWinBluetoothSocket.Destroy routine in System.Win.Bluetooth. For some reason, the TWinBluetoothSocket destructor is called in a C++ application, even though Bluetooth is not used.

The problem is that WSACleanup() is being called by the TWinBluetoothSocket destructor, but WSAStartup() had never been called, so WSACleanup() returns an error.

This occurs when the Mongo driver is used in a C++ application, even when the TFDConnection is in a Delphi unit, as long as the Mongo driver is selected and Connected is set to true in design or runtime.

No MongoDB server is needed to reproduce this; just set Connected to be true in a button click handler. Of course, an error will occur because there is no MongoDB server, but this error will occur when the application exits.

The workaround is to put this in the Constructor (from https://msdn.microsoft.com/en-us/library/windows/desktop/ms742213(v=vs.85).aspx)

WORD wVersionRequested;
WSADATA wsaData;
int err;
/* Use the MAKEWORD(lowbyte, highbyte) macro declared in Windef.h */
wVersionRequested = MAKEWORD(2, 2);
err = WSAStartup(wVersionRequested, &wsaData);
if (err != 0)
  {
     ShowMessage("err nonzero"); 
  }

Now, WSAStartup() is called, so WSACleanup() does not return an error, and the application can close.