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Forum Update on Monday, May 27th 2025

Can't get QSettings to write my settings properly

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qsettingsc++config filefontfont family
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  • R Offline
    R Offline
    radu.m10
    wrote on last edited by
    #1

    So I have the tutorial project Notepad. I am trying to use QSettings so that it saves the font,font size and other font related options in a file but it never loads them properly and when I check the config file, the values look quite weird.

    void Notepad::saveSettings()
    {
        QSettings setting("MyTE","myte");
        QFont font = this->font();
        setting.beginGroup("MainWindow");
        setting.setValue("text.font",font.toString());
        setting.setValue("text.font.family",font.family());
        setting.setValue("text.font.size",font.pointSize());
        setting.setValue("text.font.bold",font.bold());
        setting.setValue("text.font.italic",font.italic());
        setting.endGroup();
        qDebug() << "Saved";
    }
    
    
    void Notepad::loadSettings(){
        QSettings setting ("Radu","MyTE");
        QFont font = setting.value("text.font",QString()).toString();
        setting.beginGroup("MainWindow");
        QString fontFamily = setting.value("text.font.family",QString()).toString();
        int fontSize = setting.value("text.font.size",12).toInt();
        setting.setValue("text.font.size",fontSize);
        //bool fontIsBold = setting.value("text.font.bold",false).toBool();
        //bool fontIsItalic = setting.value("text.font.italic",false).toBool();
        setFont(font);
        font.setPointSize(fontSize);
        setting.endGroup();
        qDebug() << "Loaded";
    
    }
    
    

    I uncommented the bold ones because they simply don't work. I have 2 buttons that correspond to these 2 functions and I also call loadSettings() when the app first starts.

    Here is the output in the config file, that never changes and just resets to these weird values.

    [MainWindow]
    text.font=",9,-1,5,50,0,0,0,0,0"
    text.font.bold=false
    text.font.family=
    text.font.italic=false
    text.font.size=9

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    0
    • mrjjM Offline
      mrjjM Offline
      mrjj
      Lifetime Qt Champion
      wrote on last edited by mrjj
      #2

      Hi
      Its odd it doesn't have a family Qstring.

      Try to construct a font and save that

      QFont::QFont(const QString &family, int pointSize = -1, int weight = -1, bool italic = false)

      I mean instead of
      QFont font = this->font();

      Just for test.

      R 1 Reply Last reply
      0
      • Christian EhrlicherC Offline
        Christian EhrlicherC Offline
        Christian Ehrlicher
        Lifetime Qt Champion
        wrote on last edited by Christian Ehrlicher
        #3

        @radu-m10 said in Can't get QSettings to write my settings properly:

        QSettings setting("MyTE","myte");

        QSettings setting ("Radu","MyTE");

        Maybe you should try with the same values here?

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        R 1 Reply Last reply
        3
        • Christian EhrlicherC Christian Ehrlicher

          @radu-m10 said in Can't get QSettings to write my settings properly:

          QSettings setting("MyTE","myte");

          QSettings setting ("Radu","MyTE");

          Maybe you should try with the same values here?

          R Offline
          R Offline
          radu.m10
          wrote on last edited by
          #4

          @Christian-Ehrlicher Yeah they were the same, same results. The change was because I experimented that

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          0
          • SGaistS Offline
            SGaistS Offline
            SGaist
            Lifetime Qt Champion
            wrote on last edited by
            #5

            Hi,

            @radu-m10 said in Can't get QSettings to write my settings properly:

            QFont font = setting.value("text.font",QString()).toString();
            setting.beginGroup("MainWindow");

            These two lines are not in the correct order.
            Also, your "text.font" content comes from toString so you should use the QFont::fromString method to load these data.

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            Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

            R 1 Reply Last reply
            0
            • mrjjM mrjj

              Hi
              Its odd it doesn't have a family Qstring.

              Try to construct a font and save that

              QFont::QFont(const QString &family, int pointSize = -1, int weight = -1, bool italic = false)

              I mean instead of
              QFont font = this->font();

              Just for test.

              R Offline
              R Offline
              radu.m10
              wrote on last edited by
              #6

              @mrjj Seems like this way it works and outputs the proper values in the config but I still can't change them (maybe it should be like this since I initialize them with exact values, I don't know)

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              0
              • SGaistS SGaist

                Hi,

                @radu-m10 said in Can't get QSettings to write my settings properly:

                QFont font = setting.value("text.font",QString()).toString();
                setting.beginGroup("MainWindow");

                These two lines are not in the correct order.
                Also, your "text.font" content comes from toString so you should use the QFont::fromString method to load these data.

                R Offline
                R Offline
                radu.m10
                wrote on last edited by
                #7

                @SGaist I swapped those lines.
                I am sorry I am a complete newbie but I don't really understand the fromString() part. I don't know where and what to replace. Do you mean in the loadSettings function or saveSettings function? I don't know where to call that method.

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                • SGaistS Offline
                  SGaistS Offline
                  SGaist
                  Lifetime Qt Champion
                  wrote on last edited by
                  #8

                  Did you read the QFont toString and fromString documentation ?
                  @SGaist said in Can't get QSettings to write my settings properly:

                  QFont font = setting.value("text.font",QString()).toString();

                  That's the line I suggest to fix.

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                  Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                  R 1 Reply Last reply
                  0
                  • SGaistS SGaist

                    Did you read the QFont toString and fromString documentation ?
                    @SGaist said in Can't get QSettings to write my settings properly:

                    QFont font = setting.value("text.font",QString()).toString();

                    That's the line I suggest to fix.

                    R Offline
                    R Offline
                    radu.m10
                    wrote on last edited by
                    #9

                    @SGaist I've read it. I understand what it should do but still I don't exactly know how to implement it. If I just change .toString with .fromString() it doesn't work. Also I don't know where the parameter "&description" should come from. Also, this might fix some things about loading the settings but still, the save function doesn't even change the output of the font size in the config file which is just an integer. It just stays at a default "9".

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                    • SGaistS Offline
                      SGaistS Offline
                      SGaist
                      Lifetime Qt Champion
                      wrote on last edited by
                      #10

                      Nowhere was it written that you should change your toString line.

                      The description is what you stored in the QSettings under "text.font".

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                      • SGaistS SGaist

                        Nowhere was it written that you should change your toString line.

                        The description is what you stored in the QSettings under "text.font".

                        R Offline
                        R Offline
                        radu.m10
                        wrote on last edited by
                        #11

                        @SGaist Ok, thanks. I got my head around that. Now I still have the saving issue. Did you spot any mistakes in the save function?
                        Whenever I hit the save button the settings just revert to default values. Could it be something with "this->font()" ?
                        If I initialize a font with exact parameters it seems to work. But the save function saves just defaults even if I change the font inside the editor and save afterwards.

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                        0
                        • SGaistS Offline
                          SGaistS Offline
                          SGaist
                          Lifetime Qt Champion
                          wrote on last edited by
                          #12

                          @radu-m10 said in Can't get QSettings to write my settings properly:

                          QFont font = setting.value("text.font",QString()).toString();
                          setting.beginGroup("MainWindow");
                          QString fontFamily = setting.value("text.font.family",QString()).toString();
                          int fontSize = setting.value("text.font.size",12).toInt();
                          setting.setValue("text.font.size",fontSize);
                          //bool fontIsBold = setting.value("text.font.bold",false).toBool();
                          //bool fontIsItalic = setting.value("text.font.italic",false).toBool();
                          setFont(font);
                          font.setPointSize(fontSize);
                          setting.endGroup();
                          qDebug() << "Loaded";

                          You should cleanup that function, you call setFont before finishing setting the font's parameters.

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                          Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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                          1
                          • nageshN Offline
                            nageshN Offline
                            nagesh
                            wrote on last edited by
                            #13

                            @radu-m10 First of all make both saving and retrieving instances of QSettings same as pointed by @Christian-Ehrlicher then do the rest of the experimentation

                            QSettings setting("MyTE","myte");
                            
                            QSettings setting ("Radu","MyTE");
                            
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                            • R Offline
                              R Offline
                              radu.m10
                              wrote on last edited by
                              #14

                              I fixed this by setting QFont font = this->font(); to ui->appName->font(); in case anyone comes across this.

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