Learn How To Use FireDAC In The Dynamic-Link Libraries With DLL Sharing Sample In Delphi
To this end, the sample uses the CliHandle and SharedCliHandle properties of the TFDConnection class. Location You can find the DLLSharing sample project at: Start | Programs | Embarcadero RAD Studio Sydney | Samples and then navigate to: Object PascalDatabaseFireDACSamplesComp LayerTFDConnectionDLL_Sharing Subversion Repository: You can find Delphi code samples in GitHub Repositories. Search by name into the samples repositories according to your RAD Studio version. How to Use the Sample Navigate to the location given above and open Project1.dproj. Press F9 or choose Run > Run. Files File in Delphi Contains Project1.dprojProject1.dpr The project itself. Unit1.pasUnit1.fmx The main form. Project2.dprojProject2.dpr The DLL. Unit2.pasUnit2.fmx The DLL form. Implementation The sample uses FireDAC to implement a connection with a dynamic-link library. To this end, the sample implements three buttons named: Button1, Button2 and Button3. Each button handles a OnClick event to implement the following features: Load a DLL Show data Unload the DLL Load DLL To transfer a connection between an application and a DLL, the sample transfers the TFDCustomConnection.CliHandle property value to the DLL. The handle must be assigned to the TFDCustomConnection.SharedCliHandle property. After the TFDCustomConnection.SharedCliHandle is assigned, the DLL connection can be activated by setting the Connected property to True. Note that there is no need to set up a connection definition, including DriverID. // Application code: FhDll: THandle; // … procedure TForm1.Button1Click(Sender: TObject); begin FhDll := LoadLibrary(PChar(‘Project2.dll’)); @FpShowData := GetProcAddress(FhDll, PChar(‘ShowData’)); end // DLL code: class procedure TForm2.ShowData(ACliHandle: Pointer); var oForm: TForm2; begin oForm := TForm2.Create(Application); oForm.FDConnection1.SharedCliHandle := ACliHandle; oForm.FDConnection1.Connected := True; oForm.FDQuery1.Active := True; oForm.Show; end; 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 // Application code: FhDll: THandle; // … procedure TForm1.Button1Click(Sender: TObject); begin FhDll := LoadLibrary(PChar(‘Project2.dll’)); @FpShowData := GetProcAddress(FhDll, PChar(‘ShowData’)); end // DLL code: class procedure TForm2.ShowData(ACliHandle: Pointer); var oForm: TForm2; begin oForm := TForm2.Create(Application); oForm.FDConnection1.SharedCliHandle := ACliHandle; oForm.FDConnection1.Connected := True; oForm.FDQuery1.Active := True; oForm.Show; end; Show data Then, the connection can be used as a normal database connection: TShowDataProc = procedure (ACliHandle: Pointer); stdcall; // … FpShowData: TShowDataProc; // … procedure TForm1.Button3Click(Sender: TObject); begin FpShowData(FDConnection1.CliHandle); end TShowDataProc = procedure (ACliHandle: Pointer); stdcall; // … FpShowData: TShowDataProc; // … procedure TForm1.Button3Click(Sender: TObject); begin FpShowData(FDConnection1.CliHandle); end Unload DLL To unload the dynimic-link library, the sample implements the following code: TShutdownProc = procedure; stdcall; // … FpShutdown: TShutdownProc; // … procedure TForm1.Button2Click(Sender: TObject); begin FpShutdown(); FreeLibrary(FhDll); end; TShutdownProc = procedure; stdcall; // … FpShutdown: TShutdownProc; // … procedure TForm1.Button2Click(Sender: TObject); begin FpShutdown(); FreeLibrary(FhDll); end; Head over and check out the full sample source code for DLL sharing with FireDAC in Delphi.
