controller.js

angular
.module('ionicApp.state.CampaingCategoryController', [])
.controller('CampaingCategoryController', ['$scope','CampaingCategoryFactory', function ($scope, CampaingCategoryFactory) {
  console.log('CampaingCategoriesController loaded');

  // CampaingCategoryFactory.hello();
  // CampaingCategoryFactory.categories();
  // CampaingCategoryFactory.category();

  $scope.categories = CampaingCategoryFactory.categories().then(function(data){
    $scope.dados = data;
  },function(){
    //erro ao buscar os dados
  };

}]);

factory.js

angular
.module('ionicApp.state.CampaingCategoryFactory', [])
.factory('CampaingCategoryFactory', function($http, $q){

  var sayHello = function() {
    console.log('hello from factory');
  };

  var getCampaingCategories = function() {
    var deferral = $q.defer();
    $http({
      method: 'GET',
      url: 'http://0.0.0.0:3000/campaing_categories'
    }).success(function(data){
      deferral.resolve(data);
    }).error(function(){
      deferral.reject();
    });
    return deferral.promise;
  };

  var getCategory = function() {

  };

  return {
    categories: getCampaingCategories,
    category: getCategory,
    hello: sayHello
  }

})