How to check flutter application is running in debug?

Issue

I have a short question. I’m looking for a way to execute code in Flutter when the app is in Debug mode. Is that possible in Flutter? I can’t seem to find it anywhere in the documentation.

Something like this

If(app.inDebugMode) {
   print("Print only in debug mode");
}

How to check if the flutter application is running in debug or release mode?

Solution

---

While this works, using constants kReleaseMode or kDebugMode is preferable. See Rémi’s answer below for a full explanation, which should probably be the accepted question.

---

The easiest way is to use assert as it only runs in debug mode.

Here’s an example from Flutter’s Navigator source code:

assert(() {
  if (navigator == null && !nullOk) {
    throw new FlutterError(
      'Navigator operation requested with a context that does not include a Navigator.\n'
      'The context used to push or pop routes from the Navigator must be that of a '
      'widget that is a descendant of a Navigator widget.'
    );
  }
  return true;
}());

Note in particular the () at the end of the call – assert can only operate on a boolean, so just passing in a function doesn’t work.

Answered By – rmtmckenzie

Answer Checked By – Candace Johnson (FlutterFixes Volunteer)