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()).