Save values to a config file

[JonB]

@Sucharek
So it isn't writeable. Which we already know, because resource files are not writeable. You cannot set settings in a resource file. That's the answer.

Hi, I want to save some variable values into a config file.

I tried doing it with QSettings and resources, but it doesn't seem to work.

Yes, it does not work.

[Sucharek]

Ok, so , can I use like a full path? (C:/...)

[mchinand]

No, resource files don't have a location on disk that you can specify other than how you have above (:/...), they are stored embedded in the executable.

[SGaist]

Hi,

If you properly configure your QApplication, QSettings will by default store your settings in the appropriate location for the OS your application runs on.

If you really want to have a file, then use QStandardPaths to query a suitable folder.

[Sucharek]

Ok, so how do I store it in the :/config.ini now?

[SGaist]

As was already explained several times by my fellows on this thread: you cannot write in the resources.

These are read-only data embedded in your executable.

[Sucharek]

Oh, ok so now can I use the QStandardPaths? And if so, how?

[SGaist]

Where do you want to store your configuration ?

[Sucharek]

Well, I'm building the app for an Android device, so I would put it to: /data/data/org.qtproject.example.clicker/
if reading/writing to that folder isn't possible (without root), I would put it to:
/sdcard/Android/data/org.qtproject.example.clicker/

[J.Hilk]

@Sucharek

I actually have a ini file that I ship in one of my applications with the resource system. On startup I check, if my ini file exists in the relating appdata system.
If not I copy it from the resources.

This is made for Windows, but since its Qt, it should work just as well for Android.

Here are the bare bone functions:

//From to create class PreAppTasks:
void PreAppTasks::copyIniToDestDir()
{
    QFile *destFile = getDestIniFile();
    //QFile *orgFile  = getOrgIniFile();
    //in your case simply:
    QFile *orgFile = new File(":/config/config.ini");

    if(orgFile){
        if(destFile && destFile->exists()){
            //Both Files exists: implement your logic, for this case here
        } else {
            //DestFile does not exist (propably the first program execution) -> simply copy from install folder
            //But first, create the folder, if it does not exist
            QFileInfo info(destFile->fileName());
            info.setFile(info.absolutePath());
            if(!info.exists()){
                QDir d;
                d.mkpath(info.absoluteFilePath());
            }
            orgFile->copy(destFile->fileName());
        }
    }

    if(destFile){
        destFile->deleteLater();
        destFile = nullptr;
    }
    if(orgFile){
        orgFile->deleteLater();
        orgFile = nullptr;
    }
}


QFile *PreAppTasks::getDestIniFile()
{
//in your case:
    return new QFile(QStandardPaths::writableLocation(QStandardPaths::AppDataLocation) + QString("/config/config.ini"));
}

//In main.cpp (AFTER application instance creation!)
int main(int argc, char *argv[])
{
    QGuiApplication a(argc, argv);
    PreAppTasks::copyIniToDestDir();
....
    return a.exec();
}

[Sucharek]

@J-Hilk Thanks for the reply.
I'm not home right now, so I'll try it later.
Then I'll inform you if it works.

[Sucharek]

Hi, so I tried to add it to my code, but I don't know where.
Could you please tell me how to do it, or do I need to create a new C++ Class?

[SGaist]

@J-Hilk said in Save values to a config file:

//In main.cpp (AFTER application instance creation!)
int main(int argc, char *argv[])
{
QGuiApplication a(argc, argv);
PreAppTasks::copyIniToDestDir();
....
return a.exec();
}

[Sucharek]

@SGaist Yes, I've seen that, but I want to know where to put the code before.

//From to create class PreAppTasks:
void PreAppTasks::copyIniToDestDir()
{
    QFile *destFile = getDestIniFile();
    //QFile *orgFile  = getOrgIniFile();
    //in your case simply:
    QFile *orgFile = new File(":/config/config.ini");

    if(orgFile){
        if(destFile && destFile->exists()){
            //Both Files exists: implement your logic, for this case here
        } else {
            //DestFile does not exist (propably the first program execution) -> simply copy from install folder
            //But first, create the folder, if it does not exist
            QFileInfo info(destFile->fileName());
            info.setFile(info.absolutePath());
            if(!info.exists()){
                QDir d;
                d.mkpath(info.absoluteFilePath());
            }
            orgFile->copy(destFile->fileName());
        }
    }

    if(destFile){
        destFile->deleteLater();
        destFile = nullptr;
    }
    if(orgFile){
        orgFile->deleteLater();
        orgFile = nullptr;
    }
}


QFile *PreAppTasks::getDestIniFile()
{
//in your case:
    return new QFile(QStandardPaths::writableLocation(QStandardPaths::AppDataLocation) + QString("/config/config.ini"));
}

That code

[J.Hilk]

@Sucharek said in Save values to a config file:

Yes, I've seen that, but I want to know where to put the code before.

//From to create class PreAppTasks:

-> Functions/Code taken from a class that you yourself will have to create. In this case I originally named it PreAppTasks. That is why you will find the class Prefix PreAppTasks before the the function bodies. You can, but you don't have to use the same class name, that is up to your discretion.

...
Was a bit long for a comment so I shortened it.

[Sucharek]

@J-Hilk Ok, so I created a new class (PreAppTasks) and put in the code, but I have some errors:

out-of-line definition of 'copyIniToDestDir' does not match any declaration in 'PreAppTasks'
use of undeclared identifier 'getDestIniFile'
unknown type name 'File'
out-of-line definition of 'getDestIniFile' does not match any declaration in 'PreAppTasks'

my preapptasks.cpp

#include "preapptasks.h"
#include <QFile>
#include <QFileInfo>
#include <QDir>
#include <QStandardPaths>

PreAppTasks::PreAppTasks()
{

}

void PreAppTasks::copyIniToDestDir()
{
    QFile *destFile = getDestIniFile();
    //QFile *orgFile  = getOrgIniFile();
    //in your case simply:
    QFile *orgFile = new QFile(":/config/config.ini");

    if(orgFile){
        if(destFile && destFile->exists()){
            //Both Files exists: implement your logic, for this case here
        } else {
            //DestFile does not exist (propably the first program execution) -> simply copy from install folder
            //But first, create the folder, if it does not exist
            QFileInfo info(destFile->fileName());
            info.setFile(info.absolutePath());
            if(!info.exists()){
                QDir d;
                d.mkpath(info.absoluteFilePath());
            }
            orgFile->copy(destFile->fileName());
        }
    }

    if(destFile){
        destFile->deleteLater();
        destFile = nullptr;
    }
    if(orgFile){
        orgFile->deleteLater();
        orgFile = nullptr;
    }
}


QFile *PreAppTasks::getDestIniFile()
{
//in your case:
    return new QFile(QStandardPaths::writableLocation(QStandardPaths::AppDataLocation) + QString("/config/config.ini"));
}

[JonB]

@Sucharek said in Save values to a config file:

my preapptasks.cpp

So how does this compare to what is in your preapptasks.h?

[Sucharek]

@JonB Well, I didn't do anything with preapptasks.h.
What do I add in there?

[JonB]

@Sucharek
@J.Hilk gave you the definitions of a couple of methods of a PreAppTasks class. So in C++ you know you will need to provide the necessary class declaration in the .h file. Which I think from your error messages you have not done.

[Sucharek]

@JonB Ok, so I added
copyIniToDestDir();
getDestIniFile();
to the .h file, but I'm not sure what to declare there (err message: C++ requires a type specifier for all declarations).
I'm also having a problem with declaring the File variable.
On
QFile *orgFile = new File(":/config/config.ini");
when I try to declare it in the .h file (QFile File;), it doesn't fix the error message (unknown type name 'File').