Translation does not work when the text of QLineEdit is modified

[Zoltan]

I have a desktop application I want to translate. All translations work well except in the following case. I have a QLineEdit object called resultEdit whose text is updated when a pushbutton is clicked on. resultEdit can display the following strings:

const QString days[7] = {QCoreApplication::tr("Monday"), \
                         QCoreApplication::tr("Tuesday"), \
                         QCoreApplication::tr("Wednesday"), \
                         QCoreApplication::tr("Thursday"), \
                         QCoreApplication::tr("Friday"), \
                         QCoreApplication::tr("Saturday"), \
                         QCoreApplication::tr("Sunday")};

So days is a global array. One callback functions which calculates which day to print is

void ZellerGUI::on_yearEdit_editingFinished()
{
    // Calculate the day of the week
    int calculatedDay = some_integer_from_1_to_7;
    ui->resultEdit->setText(days[calculatedDay - 1]);
}

However, when I select the translation, the names of the days remain in English. It is weird as all other stings are translated well. When I opened the Linguist, it recognised all seven days. What happens in the background that the translations do not work for this global array?

[sierdzio]

Could it be that static string is built into the binary so it is not being initialized after you load translation QM file?

[Zoltan]

@sierdzio I don't know the inner working of Qt. If it is so, then what would you recommend me to modify?

[sierdzio]

This is rather inner working of C++ itself. But I am only guessing to be honest.

What you can try is to define this string array (btw. you can also use QStringList) in a singleton class that is initialized after translation is loaded, so that it gets correct data.

[Zoltan]

@sierdzio My constant variable is called from the ui. But the ui class is instantiated after the translation is loaded. Shouldn't it be OK (it isn't)?

[kshegunov]

Try something like this:

const char * const days[7] = {
    QT_TR_NOOP("Monday"),
    QT_TR_NOOP("Tuesday"),
    // ... and so on
}

void ZellerGUI::on_yearEdit_editingFinished()
{
    // ... calculate day
    QString day = QCoreApplication::tr(days[calculatedDay - 1]);
    ui->resultEdit->setText(day);
}

[Zoltan]

@kshegunov When I call lupdate on the project file, it throws these warnings:

tr() cannot be called without context

and these strings do not appear in Linguist.

[kshegunov]

Yes I think my example is rotten. Try with QT_TRANSLATE_NOOP and give it a context:

const char * const days[7] = {
    QT_TRANSLATE_NOOP("Weekdays", "Monday"),
    QT_TRANSLATE_NOOP("Weekdays", "Tuesday"),
    // ... and so on
}

[Zoltan]

@kshegunov Thank you. Now Linguist recognizes it but my application doesn't appreciate it yet. In the debugger, I also see the English name.

[kshegunov]

Well, did you translate it?

QString day = QCoreApplication::translate("Weekdays", days[calculatedDay - 1]);

[Zoltan]

@kshegunov I just used your previous solution:

QString day = QCoreApplication::tr(days[calculatedDay - 1]);

Using your last command

QString day = QCoreApplication::translate("Weekdays", days[calculatedDay - 1]);

perfectly works. Now I just have to think it over why it works.

Thank you very much for your precious help!

[kshegunov]

You're welcome.
Happy coding!

Edit:
Btw, moving the keys to the function should also work:

void ZellerGUI::on_yearEdit_editingFinished()
{
    // If this is initialized here it should work okay
    static const char * const days[7] = {
        QT_TR_NOOP("Monday"),
        QT_TR_NOOP("Tuesday"),
        // ... and so on
    };
    // ... calculate day
    QString day = QCoreApplication::tr(days[calculatedDay - 1]);
    ui->resultEdit->setText(day);
}