Generalization of some "roles" for services regarding rest resources to allow reuse of code.

services-roles.js

angular.module('services-roles', [])


.factory('HelperRole_CommonResourceGetter', function (params, errorHandler) {
	/**
	 * @constructor
	 * @param {string}                   name of the resource
	 * @param {Resource}                 Resource
	 * @param {Function.<Array|boolean>} actionArgsMapper
	 */
	return function (name, Resource, actionArgsMapper) {
		var Name = name.charAt(0).toUpperCase() + name.slice(1);
		var resource = null;

		this['get' + Name] = function (onSuccess, force) {
			var args = actionArgsMapper(params[name] && params[name]());

			if (!args) {
				errorHandler.missedResource();
				return null;
			}

			if (force || !resource || !sameRequested(resource, args[0])) {
				resource = Resource.get.apply(null, args);
			}
			resource.$promise.then(onSuccess, errorHandler.missedResource);
			return resource;
		};
	};

	function sameRequested(resource, requested) {
		angular.forEach(requested, function (value, key) {
			if (resource[key] != /* intentional coercion */ value) return false;
		});
		return true;
	}
})

.factory('HelperRole_CachedResource', function () {
	/**
	 * @constructor
	 * @param  {string}   action   name of the resource action
	 * @param  {string}   name     name of the Resource factory/part of the name of method being generated following the action name
	 * @param  {Resource} Resource resource factory
	 */
	return function (action, name, Resource) {
		var resource = null;
		this[action + name] = function () {
			return resource || (resource = Resource[action]());
		};
	};
})

.factory('cached', function () {
	return function (Resource) {
		return angular.forEach(Resource, function (action, name) {
			var resource = null;
			Resource[name] = function () {
				return resource || (resource = action.apply(this, arguments));
			};
		});
	};
});