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What is the purpose of the QSqlDatabase connection name?
sarai last edited by
QSqlDatabase implementation forces user to use addDatabase() to create a new connection and it requires a connection name (or default connection).
I'm wondering why it doesn't allow user to directly create a connection with its public constructor (without assigning a name to it). If user needs to manage multiple connections with names, it can be easily done with QMap<QString, QSqlDatabase>.
I guess there's a good reason to integrate the name - connection mapping into the class, but I couldn't find it by myself. Can anyone explain?
Did you check the documentation?
An application can use multiple connections which have different names.
You can get a specific connection by using its name:
QSqlDatabase QSqlDatabase::database(const QString & connectionName = QLatin1String( defaultConnection ), bool open = true);
sarai last edited by
@jsulm Yes, I read the document multiple times.
My question is, why QSqlDatabase class **forces **us to manage multiple instance in one way. Why it doesn't simply allow to create objects using constructor and let us manage as I need.
For example, many applications create multiple QFile objects, but QFile class doesn't force us to add name to each of them.
Well, you still can use your own implementation (like QMap<QString, QSqlDatabase> in your original post). But is there really a need for such a custom implementation? In your example you still need a string identifier for each connection, why no just use what is already there?
@sarai Yes QFile does: it's the file name. QSqlDatabase allows you to handle one or more database connections through multiple possible drivers at the same time in a easy to use fashion. The design avoids you to have to create a QSqlDatabase instance and setting it up again and again in each class/function of your application where you would like to run a query. That also means that you don't have to put your credentials everywhere in your application. That way, you can easily get the connection you need in a multi database setup.