Config file gets overwritten in qt - qt

Question

I am writing data to a config file using the following code.
QSettings settings("/root/configFile.ini",QSettings::IniFormat);
QString userName = lineEditUsername.text();
QString password = lineEditPassword.text();
QList<QString> listUsername;
QList<QString> listPassword;
settings.beginWriteArray("UserData");
for(i=0;i<listUsername.size();i++)
{
Qstring user = listUsername.at(i);
Qstring pass = listPassword.at(i);
settings.setArryIndex(i);
settings.setValue("Username",user);
settings.setValue("Password",pass);
}
settings.endArray();
}
Now when I run the code first time and give 4 or 5 values they are formed in proper order in the file. However if I run the application for second time the values start overwriting from first position. Can some one suggest me some solution for this?

Answer 1

Instead of creating and maintaining arrays and indexes, I would propose to create user credentials map and store it in the settings file as follows:
QSettings settings("/root/configFile.ini", QSettings::IniFormat);
QString userName = lineEditUsername.text();
QString password = lineEditPassword.text();
QList<QString> listUsername;
QList<QString> listPassword;
//settings.beginWriteArray("UserData");
QVariantMap userDataMapping;
for(int i = 0; i < listUsername.size() ; i++)
{
QString user = listUsername.at(i);
QString pass = listPassword.at(i);
userDataMapping[user] = pass;
//settings.setArryIndex(i);
//settings.setValue("Username",user);
//settings.setValue("Password",pass);
}
// Store the mapping.
settings.setValue("UserData", userDataMapping);
//settings.endArray();
// ...
This will store your data in ini file in the following format:
UserData=#Variant(\0\0\0\b\0\0\0\x1\0\0\0\x6\0\x64\0\x64\0\x64\0\0\0\n\0\0\0\x6\0\x62\0\x62\0\x62)
When you read settings, do something like this:
[..]
QVariant v = settings.value("UserData");
QVariantMap map = v.value<QVariantMap>();
QMapIterator<QString, QVariant> i(map);
while (i.hasNext()) {
i.next();
QString user = i.key();
QString pass = i.value().toString();
}

Answer 2

You need to retrieve the amount of existing entries before adding a new one. Something like this:
int size = settings.beginReadArray( "UserData" );
settings.endArray();
settings.beginWriteArray( "UserData" );
settings.setArrayIndex( size ); // Note: Maybe 'size - 1', not sure
// ...
settings.endArray();
setArrayIndex( size ) will move the array index to the end and will thus no longer override an existing entry