在pyqt上打开sqldatabase时没有显示任何内容

Question

我试图打开sqldatabase（.db文件），但它在pyqtQMainWindow上没有显示任何内容。下面是代码。完整的版本在Github（由MrAGi编写）

def open_database_file(self):
    path = QFileDialog.getOpenFileName(caption="Open Database",filter="Database file (*.db *.dat)")
    self.connection = SQLConnection(path)
    self.connection.open_database()

class SQLConnection():
    def __init__(self,path):
        self.path = path
        self.db = None

    def open_database(self):
        if self.db:
            self.close_database()

        self.db = QSqlDatabase.addDatabase("QSQLITE")
        if QT_VERSION_STR < '5':
            path = self.path
        else:
            path = self.path[0]
        self.db.setDatabaseName(path)
        ok = self.db.open()
        return ok