Reading [General] section in ini-files

ErikThomsen

Hi,

I am currently porting some old Delphi-based software to Qt. One task is to read the contents of a large number of Windows ini-files. These files are pre-made, and are used by a number of different tools, so the format cannot be changed.

I use the QSettings class to read these ini-files. My problem is, that the QSettings functions cannot access the [General] section. For a reason that I don't quite understand, Qt uses the section name [%General] instead of [General]. Ususally, this wouldn't be a problem, because most softwares only read the ini-files they have written themselves.

However, I have to read the [General] section (without %). So my question is: Has anybody found a way for the QSettings functions to read the [General] section? (I only need to read the contents – not write anything.)

My work-around would be to make my own ini-file reader, but it seems a bit "overkill" for just a percent sign.

I have tried the following approaches:

settings.beginGroup("General");
ModuleName=settings.value("ModuleName").toString();

settings.beginGroup("General/");
ModuleName=settings.value("ModuleName").toString();

ModuleName=settings.value("General/ModuleName").toString();

None of these accessed the actual [General] section.

SimonSchroeder

We let our QSettings write to the default location. So, I don't really know how Windows handles this (the default location on Windows is the registry). But I had a look what Linux does. What I found there is that if I don't specify any group values are put under the section [General]. Maybe the only thing you have to do to read the [General] section is to not use a group. It might be that just for your own group General Qt will put a % in front of the name to distinguish it from the non-group stuff.

Christian Ehrlicher

Copy the ini-file, replace [General] with something different and read this.

ErikThomsen

@Christian-Ehrlicher
Unfortunately, this is not possible, as this is a large collection of ini-files that a number of different software tools are already using. Modifying the ini-files is not an option.

Christian Ehrlicher

@ErikThomsen Why can't you copy the ini file before trying to read it with Qt?

J.Hilk

or, if copying is not possible, why not read it in memory change General there and read it than with QSettings

surely the file is not Gbytes big ?

ErikThomsen

@Christian-Ehrlicher
It is not one file. It is a large number of files, full of configuration data, used by numerous different software tool.
These files gradualy increase in number, and occationally the contents change. Therefore, we need a common pool of these files, so only one set of files is maintained.

Christian Ehrlicher

I still don't understand why you can't copy the file to a temp dir, modify it and read it with Qt...

ErikThomsen

@J-Hilk
No, the files are not huge. And your solution would probably work.
My own solution will probaby be something similar, such as parsing the [General] section as a text file. All the other sections work as they should.

I just hoped that someone had found a way to tweak QSettings directly.

@Christian-Ehrlicher
In that case, it will be necessary for the software to do this everytime it is used. I find that impratical.

Christian Ehrlicher

@ErikThomsen said in Reading [General] section in ini-files:

In that case, it will be necessary for the software to do this everytime it is used. I find that impratical.

And what's different from your / @J-Hilk's idea? It's a simple class derived from QSettings...

ok, deriving does not work due to QSettings constraints, ~12 lines of code without error checking...

class MySettings
{
public:
  MySettings(const QString &fn)
  {
    QFile f(fn);
    f.open(QIODevice::ReadOnly);
    QByteArray ba = f.readAll();
    f.close();
    temp.open();
    temp.write(ba.replace("[General]", "[Blub]"));
    temp.close();
    m_settings = new QSettings(temp.fileName(), QSettings::IniFormat);
  }
  ~MySettings()
  {
    delete m_settings;
  }
  QSettings *settings()
  {
    return m_settings;
  }
private:
  QSettings *m_settings = nullptr;
  QTemporaryFile temp;
}

SimonSchroeder

We let our QSettings write to the default location. So, I don't really know how Windows handles this (the default location on Windows is the registry). But I had a look what Linux does. What I found there is that if I don't specify any group values are put under the section [General]. Maybe the only thing you have to do to read the [General] section is to not use a group. It might be that just for your own group General Qt will put a % in front of the name to distinguish it from the non-group stuff.

ErikThomsen

@Christian-Ehrlicher
I just need to read some pre-made ini-files. Not modify them.
But I have solved the issue by reading the ini-file as a text file, and parsing the lines in the [General] section manually.

Christian Ehrlicher

@ErikThomsen said in Reading [General] section in ini-files:

I just need to read some pre-made ini-files. Not modify them.

I never said that you should modify them... read my osts and suggestion properly!

ErikThomsen

@SimonSchroeder
Aaaah! That's interesting!
Will try it. Thanks!

Due to the posting frequency limit for newbies, I had plenty om time to try it out.
It works nicely.

Instead of

settings.beginGroup("General");

which accesses [%General], I use

settings.beginGroup("");

which accesses [General]. The compiler gives me a warning, but that can be ignored.

ErikThomsen

@Christian-Ehrlicher
I apologize for being stupid. If you didn't mean to copy and modify the files, then I simply don't understand your suggestion.

In any case, the hint from @SimonSchroeder solved the issue.

Christian Ehrlicher

I use the file, generate a modified temoprary file and use this for QSettings. The temporary file is deleted right after the class gets destructed. So it's the same as @J-Hilk suggested. I never modified the original one so I don't see what's your problem with my suggestion...

SimonSchroeder

@ErikThomsen said in Reading [General] section in ini-files:

I use
settings.beginGroup("");

which accesses [General]. The compiler gives me a warning, but that can be ignored.

I am not sure what the compiler warns about. But, you don't have to start any group. Just drop the beginGroup(...) altogether (and also the corresponding endGroup()).