Lost connection?

[PJN]

Hello

I have a program that is on a wifi connection and that sometimes loses the connection.
I want to do a test if I have a connection to server.
I'm using MyQuery with Cached Updates and using mysql direct.
If I use MyConnection.Ping () to test/reconnect to the server and do not have any connection to the server all my updated data is gone.


To recreate the problem:

Code: Select all

MyConnection->Connect ();
MyQuery->CachedUpdates = true;
MyQuery->Sql->text = "Select * Table1 limit 10";
MyQuery->Active = true;
MyQuery->FieldByName("Field1")->AsString = "SampleData";


// Now down the server and test ping().

try{
  MyConnection->Ping ();   // Connection is closed and MyQuey->Active is set to false
}
catch(...){ // Connection lost and MyQuery not active }

If the server is up and running MyConnection reconnect with no problem.
What I want to do is to have a function that can check if I have a connection to the server and then creates/reconnects to the server.
If I do not have a connection to the server MyConnection uses the existing open connection to the server this keeps the data in the MyQuery.


My Existing Sample:

Code: Select all

//---------------------------------------------------------------------------
class PACKAGE TMyConnectionEx : public TMyConnection
{
private:
protected:
public:
	__fastcall TMyConnectionEx(TComponent* Owner);
   
   
   int	__fastcall IsConnectionOK(void)
   {
	 
	 TMyConnection *ConTest = NULL;
	 int Ok;
	 try{
		 if(Connected != true)
		 {
			 Ping();
			 return !Connected;
		 }
		 if(Ok = IConnection()->MySQLAPI->mysql_ping(IConnection()->MySQL))
		 {
 		     try
		     {
					   ConTest = new TMyConnection(this);
					   ConTest->Assign(this);
					   ConTest->Connect();
					   if(ConTest->Connected == true)
					   {
						   if(ConTest) delete ConTest;
						   try          { Ping();  }
						   catch(...)   { Ok = !Connected; }
						   return Ok;
					   }
				  }
				  catch(...)
				  {
						  if(ConTest)   delete ConTest;
						  return Ok;
				  }
			 }
			 return Ok;
	 }
	 catch(...)
	 {
	   return  1;
	 }
   }
__published:
};

Please implement a function or a sample on how to do this in better way.

[Antaeus]

Presently MyDAC does not support such functionality. When connection to the server is lost, all linked datasets becomes closed. Next version of MyDAC will support Disconnected Model. That means if connection to the server is lost, TMyConnection object will try to reconnect to the server automatically without closing linked datasets.