Database result with connection name in all project

[elicat]

Hello, my problem of day is: how use in all class of my project one ore more database? I have try with setting connection name.

In my project I have a class with name "DataBase" that opens a database giving a name to the connection like that:

db = QSqlDatabase::addDatabase(driver_db, "pippo");

In the same project in several parts I have to use the same database. I thought about connecting to the database by calling the connection with its name

DataBase *database = new DataBase;
QSqlDatabase dbstructure = QSqlDatabase::database("pippo");
Although the connection is open and I do not have any error reports when I try to read a value of a selected record I do not return anything to the query.size () indicates me -1
        if(database->openDataBase(dbstructure)) {
        QSqlQuery querydb(dbstructure);
        QString strqrysearchprogram = "select * from nome_Tabella where Item  = '1'" ;
        if(querydb.exec(strqrysearchprogram)) {
            if (querygrare.first()) {
                qDebug() << querygrare.size();
                QString valuefield = querygrare.value("nameField").toString();
                qDebug() << "valuefield : " << valuefield;
                qDebug() << "qry: " << strqrysearchprogram;
            }
        } else {
            qDebug() << "record non trovato in qry: " << strqrysearchprogram;
        }
    } else {
        qDebug() << "ERROR open Database";
    }

Where am I wrong? Is it correct to recall the database with the name of the connection? I state that I have checked the selection string that is passed and the record exists.

[SGaist]

Can you show your complete code ?

[elicat]

Yes, this is method for connection:

 QSqlDatabase DataBase::connectToDataBase(int type_db, QString path_and_name_db, QString driver_db, QString user_db, QString pass_db, QString hostname_db, QString port_db, QString conn_db, QString conn_name ) {
    db = QSqlDatabase::addDatabase(driver_db, conn_name);
    db.setUserName(user_db);
    db.setPassword(pass_db);
    db.setHostName(hostname_db);
    if (user_db != NULL) {
        db.setUserName(user_db);
    }
    if (pass_db != NULL) {
        db.setPassword(pass_db);
    }
    if (port_db != NULL) {
        //db.setPort(port_db);
    }
    if (conn_db != NULL) {
        db.setConnectOptions(conn_db);
    }
    switch (type_db)
    {
        case 0:
            // accesso a database QSLite
            db.setDatabaseName(path_and_name_db);
        break;

        case 1:
            // accesso a database MSACCESS .mdb
            db.setDatabaseName("DRIVER={Microsoft Access Driver (*.mdb)};FIL={MS Access};DBQ=" + path_and_name_db);
        break;

        case 2:
            // accesso a database MSACCESS .accdb
            db.setDatabaseName("DRIVER=Provider=Microsoft.ACE.OLEDB.12.0;FIL={MS Access};DBQ=" + path_and_name_db);
        break;

        default:
            // accesso a database MSACCESS .mdb
            db.setDatabaseName("DRIVER={Microsoft Access Driver (*.mdb)};FIL={MS Access};DBQ=" + path_and_name_db);
        break;
    }
    return db;
}

This is methode for open:

 bool DataBase::openDataBase(QSqlDatabase dbcheckopen) {
    if (dbcheckopen.isOpen()) {
        // first controll if is open already
        return true;
    } else {
        if(dbcheckopen.open()){
            return true;
        } else {
            return false;
        }
    }
}

Do you need other?

[JonB]

@elicat
I could be wrong(! @SGaist ?), but you are passing QSqlDatabase dbcheckopen to your openDataBase function. That takes a copy of the parameter, and opens that. Shouldn't it be a QSqlDatabase& dbcheckopen?

[elicat]

@JonB said in Database result with connection name in all project:

I could be wron

for gestion of memory is sure is better but in function open i only check

[JonB]

@elicat said in Database result with connection name in all project:

for gestion of memory is sure is better but in function open i only check

Pardon?

If you mean you only check whether it's already open, you don't, you call dbcheckopen.open() if it is not, it's your code....

[MrShawn]

QSqlDatabase dbstructure = QSqlDatabase::database("pippo");
Although the connection is open and I do not have any error reports when I try to read a value of a selected record I do not return anything to the query.size () indicates me -1
        if(database->openDataBase(dbstructure)) {
                  .....
        }

try this instead:

QSqlDatabase dbstructure = QSqlDatabase::database("pippo");

        if(dbstructure.open()) {
                  .....
       }

also include <QSqlError>
and output

qDebug() << querydb.lastError().text();
//and
qDebug() << dbstructure.lastError().text();

on your failures to get more insight.