DB unique instance

[Zoptune]

Hello,

I don't know how to share the connection between 2 class.
Should i use the singleton design pattern ?

Thanks for help

[mrjj]

hi
Qt can share the default connection/db internally.
So you can open db in one class
and if you use QSqlQuery in rest of program and if you dont supply
DB to QSqlQuery , it will use this default one.

The class holding the DB must of course live on.

[kshegunov]

@Zoptune said:

Should i use the singleton design pattern ?

No. You shouldn't ever use that unless you're aware of its many, many drawbacks.

To expand a bit on @mrjj's answer, you can name your connections when creating them with QSqlDatabase::addDatabase, then you can retrieve your connection by its name through QSqlDatabase::database. Something like this:

// In class 1, main() or w/e
QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE", "mysqlite"); //< Create sqlite connection, name it

// In class 2
QSqlDatabase db = QSqlDatabase::database("mysqlite"); //< Use the name to retrieve the connection

If you're using only one connection in your program, then you can skip the names (Qt provides a default name), so you can do it simply like:

// In class 1, main() or w/e
QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE"); //< Create sqlite connection, and use the default name

// In class 2
QSqlDatabase db = QSqlDatabase::database(); //< Get the connection with the default name

Kind regards.

[Zoptune]

@kshegunov

This is the solution i used :)