angular directive to validate with a blacklist

blacklist.js

angular.module('myapp.directive.blacklist', []).
directive('maBlacklist', [
  function() {
    return {
      restrict: 'A',
      require: 'ngModel',
      scope: {'blacklist':'=gsBlacklist'},
      link: function($scope, $elem, $attrs, modelCtrl) {

        var check = function(value) {
          var blacklist = $scope.blacklist;
          return !_.isArray(blacklist) || blacklist.indexOf(value) === -1;
        }

        //For DOM -> model validation
        modelCtrl.$parsers.unshift(function(value) {
          // console.log("parsing", value);
          var valid = check(value);
          modelCtrl.$setValidity('blacklist', valid);
          //return valid ? value : undefined;
          return value;
        });
        //For model -> DOM validation
        modelCtrl.$formatters.unshift(function(value) {
           modelCtrl.$setValidity('blacklist', check(value));
           return value;
        });
      }
    };
  }
]);