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  1. 79978e5 chore: set max SDK version to <3.0.0 (#40) by Patrice Chalin · 4 weeks ago master 0.11.3+2
  2. 0bedaa1 Delete PATENTS by Kevin Moore · 5 months ago
  3. c4f83a0 Remove dartium from travis tests (#38) by Kevin Moore · 6 months ago
  4. da053fe Allow chrome tests to fail (#37) by Kevin Moore · 7 months ago
  5. 46077ac Enable travis, add analysis_options, other cleanup (#35) by Kevin Moore · 10 months ago


By default, the logging package does not do anything useful with the log messages. You must configure the logging level and add a handler for the log messages.

Here is a simple logging configuration that logs all messages via print.

Logger.root.level = Level.ALL;
Logger.root.onRecord.listen((LogRecord rec) {
  print('${}: ${rec.time}: ${rec.message}');

First, set the root [Level]. All messages at or above the level are sent to the [onRecord] stream.

Then, listen on the [onRecord] stream for [LogRecord] events. The [LogRecord] class has various properties for the message, error, logger name, and more.

Logging messages

Create a [Logger] with a unique name to easily identify the source of the log messages.

final Logger log = new Logger('MyClassName');

Here is an example of logging a debug message and an error:

var future = doSomethingAsync().then((result) {
  log.fine('Got the result: $result');
}).catchError((e, stackTrace) => log.severe('Oh noes!', e, stackTrace));

When logging more complex messages, you can pass a closure instead that will be evaluated only if the message is actually logged:

log.fine(() => [1, 2, 3, 4, 5].map((e) => e * 4).join("-"));

See the [Logger] class for the different logging methods.