QT QSqlDatabase open() function creates a sqlite database

Question

I'm trying to open a sqlite database file in QT using .open() function and if the file doesn't exit, .open() doesn't return a false, it just creates a new file in the given directory. My code:

QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName("C:/sqlite/newDB.db");

    if(!db.open()){
        ui->test->setText("Fail");
    }
    else{
        ui->test->setText("Success");
    }

How to make it return a true or false ?

Mike · Accepted Answer · 2016-05-08 21:12:06Z

5

you can't make it return true or false, this is how it works. . .

However, you can check for file existence before opening the database using QFile::exists("C:\\sqlite\\newDB.db"). After that, if it is existent you can try a query like this to make sure it is not corrupted:

QSqlQuery q;
if(!q.exec("SELECT name, sql FROM sqlite_master WHERE type='table' ;")){
    //corrupt sqlite file
}

the final code may look like this:

if(!QFile::exists("C:\\sqlite\\newDB.db")){
    //file does not exist
}
QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
db.setDatabaseName("C:\\sqlite\\newDB.db");
if(!db.open()){
    //Database open error
}
{
    QSqlQuery q;
    if(!q.exec("SELECT name, sql FROM sqlite_master WHERE type='table' ;")){
        //corrupt or invalid sqlite file
}

edited May 8, 2016 at 21:12

answered May 8, 2016 at 4:42

Mike

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5 Comments

CL. Over a year ago

Did you actually test this? Because the newly created database will also contain the system table.

Mike Over a year ago

@CL. , yes, this is tested. sorry, what is the system table?

CL. Over a year ago

It's the table you're trying to access. Anyway, I misunderstood the logic; this should work fine.

ReeSSult Over a year ago

Thanks. However, QT documentation says "Opens the database connection using the current connection values. Returns true on success; otherwise returns false"

Mike Over a year ago

@ReeSSult , and in case of a non existent sqlite file, it creates a new empty database and connects to it, thus it succeeds and returns true. . . since this behavior is not suitable to you, we check if the file exists first. . .

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