myAJResource.js

 var module = angular.module( 'my.resource', [ 'ngResource' ] );
 
 module.factory( 'Resource', [ '$resource', function( $resource ) {
   return function( url, params, methods ) {
     var defaults = {
       update: { method: 'put', isArray: false },
       create: { method: 'post' }
     };
     
     methods = angular.extend( defaults, methods );
 
     var resource = $resource( url, params, methods );
 
     resource.prototype.$save = function() {
       if ( this.id === undefined ) {
         return this.$create.apply(this, arguments);
       }
       else {
         return this.$update.apply(this, arguments);
       }
     };
 
     return resource;
   };
 }]);