QSqlQueryModel as return value

[vittorio]

Hi all,
I try to write a function, which generates a QSqlQueryModel and returns this model to the calling function. First I thought, this should be an easy thing but obviously I was wrong!
I searched the forum but found no information, which could help me...

My function:

QSqlQueryModel DBManager::loadConnectionData()
{
    QSqlQuery *qry = new QSqlQuery(dbSQLite);
    QSqlQueryModel model;
    qry->prepare("select * from tbl_connections");
    qry->exec();
    model.setQuery(*qry);
    return model;
}

QSqlQueryModel DBManager::loadConnectionData()
{
    QSqlQuery *qry = new QSqlQuery(dbSQLite);
    QSqlQueryModel model;
    qry->prepare("select * from tbl_connections");
    qry->exec();
    model.setQuery(*qry);
    return model;
}

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When I try to compile the code I get following error message:
Fehler: C2280: 'QSqlQueryModel::QSqlQueryModel(const QSqlQueryModel &)': attempting to reference a deleted function

I didn't find an explanation on the net which helped me to understand the problem, so maybe someone here is so kind to help me a little bit?

Thanks in advance!!

Viktor

[d_stranz]

You cannot create a QSqlQueryModel on the stack and return it as the return value of a function. The class has neither a copy constructor nor an assignment operator, one of which would be required to accomplish this. Furthermore, your QSqlQuery is a memory leak. You might have more luck using something like this:

QSqlQueryModel * DBManager::loadConnectionData()
{
    QSqlQuery qry(dbSQLite);
    QSqlQueryModel * model = new QSqlQueryModel( this );
    qry,prepare("select * from tbl_connections");
    qry.exec();
    model->setQuery(qry);
    return model;
}

QSqlQueryModel * DBManager::loadConnectionData()
{
    QSqlQuery qry(dbSQLite);
    QSqlQueryModel * model = new QSqlQueryModel( this );
    qry,prepare("select * from tbl_connections");
    qry.exec();
    model->setQuery(qry);
    return model;
}

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You probably also need a ";" at the end of your select statement for proper syntax. Remember to call delete on the "model" instance after you are done with it to avoid a memory leak on that.

[anda_skoa]

Or instead if fiddling with the transient QSqlQuery here use the setQuery() overload that takes a query string and database connection.

Cheers,
_

[vittorio]

thanks for your help, now it works!