Patch for angularjs $resource to send POST or PUT depending on ID field

fz.restsource.js

// This patches the $resource.$save function
// to make a PUT when an ID is present.
// Inspired by http://kirkbushell.me/angular-js-using-ng-resource-in-a-more-restful-manner/

'use strict';

angular.module( 'fz.restsource', [ 'ngResource' ] )
  .factory('$restsource', function($resource) {

    var idField = '_id';

    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.$save = function() {
      if (!this[idField] ) {
        return this.$create.apply(this, arguments);
       } else {
        return this.$update.apply(this, arguments);
       }
     };

     return resource;
   };
 });