如何使用提供者而不是函数来修饰$log服务

Question

我正在尝试装饰angularjs中的$log服务，以便通过http将日志发送到后端。我设法做到了这一点，使用这样的东西:

app.config(['$provide', function ($provide) {
    $provide.decorator('$log', ['$delegate', loggerDecorator]);
}]);
var loggerDecorator = function ($delegate) {
   ...decorating logic
   $delegate.log = prepareLogFn($delegate.log);
   return $delegate;
}

这很好，但是，我更愿意使用提供者作为装饰器，以便我可以在模块的配置阶段配置它，用于设置分隔符，远程api url等。

我尝试创建一个像这样的提供者:

    angular.module('mods.logging').factory(serviceId, [backendLoggingDecorator]);
    function backendLoggingDecorator() {
        var remoteUri = '';
        return {
            setRemoteUri: function (uri) {
                remoteUri = uri;
            },
            $get: function ($delegate) {
                var ajaxLogger = log4javascript.getLogger();
                var ajaxAppender = new log4javascript.AjaxAppender(remoteUri);
                ajaxAppender.setThreshold(log4javascript.Level.ALL);
                ajaxLogger.addAppender(ajaxAppender);
                function prepareLogFn(loggingFunc) {
                    return function () {
                        if (ajaxLogger) ajaxLogger.info(arguments);
                        loggingFunc.apply(null, args);
                    };
                }
                $delegate.log = prepareLogFn($delegate.log);
                return $delegate;    
            }
        };
    }

，然后执行如下操作:

app.config(['$provide', function ($provide) {
    $provide.decorator('$log', ['backendLoggingDecorator', function(bld) {
        return bld;
    }]);
}]);

Answer 1

这里有一个例子。在enhanceLogging函数中，您可以对日志做任何事情，用额外的信息装饰它，将其发布到外部服务等。

var myApp = angular.module('myApp', []).provider('logEnhancer', [function () {
	this.$get = function () {
	  return {
		enhanceAngularLog: function ($log) {
			$log.getInstance = function (context) {
			  return {
				log: enhanceLogging($log.log, context, 'log'),
				info: enhanceLogging($log.info, context, 'info'),
				warn: enhanceLogging($log.warn, context, 'warn'),
				debug: enhanceLogging($log.debug, context, 'debug'),
				error: enhanceLogging($log.error, context, 'error')
			  };
			}
		  function enhanceLogging(loggingFunc, context, level) {
			return function () {
			  var modifiedArguments = [].slice.call(arguments);
			  modifiedArguments[0] = moment().format('dddd h:mm:ss a') + ' || ' + modifiedArguments[0] + ' || from Ctrl: ' + context;
			  loggingFunc.apply(null, modifiedArguments);
			};
		  }
		}
	  };
	};
}]).run(['$log', 'logEnhancer', function ($log, logEnhancer) {
    logEnhancer.enhanceAngularLog($log);
}]).controller('LogCtrl', ['$log', '$scope', function ($log, $scope) {
	var $log = $log.getInstance('LogCtrl');
	$scope.doTest = function () {
		$log.debug("This *will* appear in your console");
	};
}]);

<script src="http://cdnjs.cloudflare.com/ajax/libs/moment.js/2.8.1/moment.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="myApp" ng-controller="LogCtrl">
  <h3>Enhance $log service</h3>
  <button ng-click="doTest()">test logger</button>
  <p>Look the console for the modified <code>$log.debug()</code> message.</p>
</div>