Is it possible to use $logProvider for logging in config block of the module?

Question

I'd like to output log messages to console when debugging. Works fine in controllers but can't get it to work in a module config block, e.g.

angular.module('MyApp', [])
  .run(function($state){
    // run stuff here
  });
  .config(function($logProvider){
    $log.debug('Config debug message');
  });

I get an error:

error TypeError: Cannot read property 'debug' of undefined

Is it possible to use the logProvider in the config block of a module?

Answer 1

$logProvider accessed during the config phase is used to configure the log service, or you can inject $provide to change/leverage the behavior of logservice using decorators. The log service itself has not been instantiated yet in your module MyApp. You could instead get a logger instance from core ng and use it for debugging.

You could do:-

 .config(function(){
     var $log =  angular.injector(['ng']).get('$log')
     $log.debug('Config debug message');
  });

$logProvider.$get will give you the constructor for logservice, you could yourself create an instance of it by calling $injector.instantiate($logProvider.$get) but the problem is that it has a dependency on window service which has not bee instantiated yet, so ultimately your logger instantiation will fail.

Another hacky way would be force angular to instantate logger by adding a decorator in the config block which you can set up as the first config block before any config logging is required, after that you can execute the ctor from $logProvider getter and get the instance of a logger.

.config(function($provide){
   //Just a dummy decorator
   $provide.decorator('$log', function($delegate){
      return $delegate;
  });

}).config(function($logProvider){
   //get logger instance
   var log = $logProvider.$get();
   log.debug("Got it");
});

Plnkr