Evgenij LegotskojFeb. 7, 2022, 7:52 a.m.

Qt/C++ Tutorial 092. Creating translations for external text sources

Today we will discuss a rather interesting option for adding translation to a Qt/C++ application. Namely, adding translations for texts from external sources when you display texts from databases, an external API, or just some other files.

Such a situation can arise in the following case, for example, analysts in your project form sets of data and texts in some external database or text files, but there is no possibility of multilingualism for some reason. And therefore, you do not have the option to select the language as an additional parameter when requesting this data. Or, for example, the final data is downloaded from an external resource and stored in a SQLite database, of course, without additional translations. But at the same time, you are developing a multilingual application and you need to somehow generate translation files for these texts, so that the translation team can translate them, and you can connect them in the application.

But in Qt it is possible to solve this problem as well. In such situations, you can also generate source code files in the same way, for example, generate them when importing data during application development, and then generate translation files with the extension *.ts , which are used in QtLinguist to translate the application to Qt, and then generate binary *.qm translation files that will be included in the application.

Let's see how it works and what needs to be done for this.

Adding source files

In order for the lupdate application to be able to create *.ts files, the project must have header and source files. But they don't have to be compiled. It turns out such an interesting trick, in which there are non-compiled files in the project, but without them it will not be possible to generate *.ts files.

pro file

Let's look at the contents of the pro file to understand which files are needed in our project.

TRANSLATIONS= myapp_en.ts\



As you can see, there are *.ts translation files, as well as two files translations_generated.h and translations_generated.cpp .
These files are generated or added by you manually, it doesn't matter, it doesn't matter how exactly you create and add these files.
The main thing is that these files have appropriate content.


You will be surprised, but we leave this file empty.


And here is the most important content.


// Uncompiled file, only as source for lupdate.exe
namespace my
namespace translation
namespace example
tr("total length");
} // namespace my
} // namespace translation
} // namespace example


Notice a few important things about this file:

  • TRANSLATOR_GUARD - which prevents the file from being compiled, we don't need it
  • namespace - namespaces create the context in which the translation will be generated. In this case, the context will be "my::translation::example"
  • Q_OBJECT - this macro will tell lupdate that there may be translation call functions here, with the help of which the translation file will be generated.

After you generate the translation files with the lupdate program, you can translate these strings in QtLinguist and then compile the binary translation files to be used correctly in your application.

Using translations

Using translation will differ in that you will not write specific text, but pass a variable and context to the translation function QCoreApplication::translate .

Let's see how it would look like with an example class. This class has a variable that contains the string to be translated, as well as a method for returning the translated value.

#include <QCoreApplication>
#include <QString>

class ExampleTranslator
    QString getTranslatedName() const
        return QCoreApplication::translate("my::translation::example", m_name.toUtf8());

    QString m_name;

The QCoreApplication::translate method, with a properly invoked context, will try to find a translation for the passed text and, if successful, will return the translated value for the active language in the application.


Thus, it is possible to perform translations of any external texts, moreover, using standard Qt tools.

We recommend hosting TIMEWEB
We recommend hosting TIMEWEB
Stable hosting, on which the social network EVILEG is located. For projects on Django we recommend VDS hosting.
- company blog
Support the author Donate

Oh, he is alive! I started to think you died of covid. Glad to see you! Good lesson.

Thanks! Yes, I returned. But I will be focused on articles and site functionality now.


Only authorized users can post comments.
Please, Log in or Sign up

Let me recommend you a great European Fornex hosting.

Fornex has proven itself to be a stable host over the years.

For Django projects I recommend VPS hosting

Following the link you will receive a 5% discount on shared hosting services, dedicated servers, VPS and VPN

View Hosting
Share on social networks

The EVILEG project has switched to a non-commercial basis and will develop solely on the enthusiasm of the site creator, the enthusiasm of users, donations and the hosting referral system

Thank you for your support

Available ways to support the project



C++ - Test 006. Enumerations

  • Result:30points,
  • Rating points-10

C++ - Тест 003. Условия и циклы

  • Result:42points,
  • Rating points-8

C++ - Test 005. Structures and Classes

  • Result:50points,
  • Rating points-4
Popular publications in the last 90 Days
Last comments

EVILEG-CORE. Caching properties of model objects using model_cached_property

Здравствуйте. В общем меня интересует такой вопрос. Я пробовал это на Like , Dislike. Как я понимаю если не перевалидировать кеш то ничего не изменится на странице. Вернётся значение из кэша? От…

Qt/C++ - Lesson 006. QSqlQueryModel – Tables in Qt with SQL-query

Здравствуйте! Подскажите как сделать запрос к базе SQLite с двумя параметрами, в итоге нужно получить не список строк, а только факт наличия строк, соответсвующи именно двум условиям. В SQL…

Django - Tutorial 011. Adding comments to the site based on Django


Django - Tutorial 011. Adding comments to the site based on Django

I read that Post and got it fine and informative.https://aflife.ru/

Django - Tutorial 023. Like Dislike system using GenericForeignKey

Хорошо. Большое спасибо. Посмотрю что из этого получится.
Now discuss on the forum

Запрос на изменение БД с помощью оператора UPDATE и странное поведение QTableView

или запрос к базе так https://www.w3schools.com/sql/sql_ref_order_by.asp или сортировка в модели через прокси модель https://doc.qt.io/qt-5/qsortfilterproxymodel.html

Как очичтисть очередь событий для конпки

нужно сделать связку qml и c++, тяжелые задачи отправляются на обработку в с++, в qml остаются только быстрые. и у кнопок есть свойство enabled: true\false при запуске\остановке з…

Развертывание QML приложения

Полностью согласен, что пример не удачный, но я так как раз попытался выразить то, что вы далее описали с примером со скадой, часть .dll и часть .qml с интерпритацией. И в Вашем ответе я ув…

Sorting the added QML elements in the ListModel

I am writing an alarm clock in QML, I am required to sort the alarms in ascending order (depending on the date or time (if there are several alarms on the same day). I've done the sorting …

HTTP server на Qt

Давно было, уже не помню как, но разрулил. Спасибо :)
© EVILEG 2015-2022
Recommend hosting TIMEWEB