Olivier Cléro

QtUpdater

11/11/2021

Presentation

QtUpdater is a tool to check for updates in your Qt application. You may use it to check applications auto-updates, but not only.

The tool downloads an appcast (JSON file) from an endpoint and compares it with QCoreApplication::applicationVersion(). The JSON looks like this:

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{
  "version": "x.y.z",
  "date": "dd/MM/YYYY",
  "checksum": "418397de9ef332cd0e477ff5e8ca38d4",
  "checksumType": "md5",
  "installerUrl": "http://your-server/your-app/win/YourApp-x.y.z.t-Windows-64bit.exe",
  "changelogUrl": "http://your-server/your-app/win/YourApp-x.y.z.t--Windows-64bit.md"
}

No GUI is included, it is up to you to build your own in C++/QtWidgets or QML/QtQuick. The QtUpdater class has all necessary signals and slots to be used in one of these technologies.

It can:

  • Check for update availability on a parameterized frequency (every start, every day…).
  • Download changelog.
  • Download installer.
  • Check if the installer validates the MD5 checksum provided in the appcast.
  • Launch the installer and quit the application.

It also comes with a QtDownloader utility that handles downloading a file to disk, or data, and exposes all these functionnality to QML.

Usage

The basic usage looks like this:

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// Create an updater.
oclero::QtUpdater updater("https://your-server/update-api/");

// Subscribe to all necessary signals. See documentation for complete list.
QObject::connect(&updater, &oclero::QtUpdater::updateAvailableChanged,
                 &updater, [&updater]() {
  if (updater.updateAvailable()) {
    qDebug() << "Update available! You have: "
      << qPrintable(updater.currentVersion())
      << " - Latest is: "
      << qPrintable(updater.latestVersion());
  } else {
    qDebug() << "You have the latest version.";
  }
});

// Start checking.
updater.checkForUpdate();

Information