Design puzzle about database connectivity architecture - c++

Question

I am designing a database browsing application, which till now had MySQL support, but recently I have started implementing supporting Sqlite too and I face some ugliness while designing the way the connectivity architecture is being implemented. This is only about the "connection" part (ie: where you get the user/db/host, or for sqlite the filename), not the database functionality. That is sorted out already.
I have a base class "Connection" which exposes "normal" methods like name(), or pure virtual methods which are like virtual string fullLocation() = 0 which returns me a string that can be used to identify the database (such as: database#host for MySql, or /etc/mydb.sqlite for Sqlite).
Now, the user of course needs to specify a database he wants to connect to, so in the GUI of the application he simply chooses the type and then fills in the credentials. And here my troubles start. I have created a MySqlConnection and an SqliteConnectionclasses, both derived from Connection but most of the cases I end up with something like:
Connection* c = 0;
if(gui->engine_name() == "MYSQL")
{
string host = gui->getHost();
string user = gui->getUser();
string password = gui->getPassword();
int port = gui->getPort();
string db = gui->getDatabase();
c = new MySqlConnection(host, user, password, db, port);
}
else
{
string dbFile = gui->getSqliteDbFile();
c = new SqliteConnection(dbFile);
}
string meta = application->use_connection(&c);
and I have the fear, that this will continue through the entire application, due to the so different nature of these two database engines.
Do you have some guidance on how to solve this in an elegant way?

Answer 1

You need pattern Factory, that will create Connection for you in abstract way. It is superficial answer.
This Factory would be nice parametrize with Builder pattern. Something like that:
ParamBuilder *b = new ParamBuilder;
if(gui->engine_name() == "MYSQL")
{
b->setHost(gui->getHost())
->setUser(gui->getUser());
->setPassword(gui->getPassword());
...
}
else
{
b->setFile(gui->getSqliteDbFile());
}
Connection *c = globalConnectionFactory->createConnection(b);

Answer 2

A much more elegant way would be designing a factory class and handling GUI inputs in the GenerateConnection() method of that factory:
void ConnectionFactory::GenerateConnection(Connection* c)
{
if(gui->engine_name() == "MYSQL")
{
string host = gui->getHost();
string user = gui->getUser();
string password = gui->getPassword();
int port = gui->getPort();
string db = gui->getDatabase();
c = new MySqlConnection(host, user, password, db, port);
}
else
{
string dbFile = gui->getSqliteDbFile();
c = new SqliteConnection(dbFile);
}
}
If you do not prefer a dependency on the gui, you can just define a struct named Parameters and update its instance according to the gui inputs and give this object into the connection generating method of connection factory.