angularjs validate input and prevent change if invalid

Question

I neeed an input field where I can enter only the values 1,2 or 3 so i\'m trying to build a directive which prevents all changes to the model if it doesn\'t match these valu

Answer 1

You could always listen to the keypress event and prevent the character from making it through. Here is a plunker

var app = angular.module('plunker', []);

app.controller('MainCtrl', function($scope) {
  $scope.name = 'World';
  $scope.validValues = ['a','1','2'];
});

app.directive('myValidator', function ($parse) {
    return {
        scope: {
          validValues: '=validValues'
        },
        link: function (scope, elm, attrs) {
          elm.bind('keypress', function(e){
            var char = String.fromCharCode(e.which||e.charCode||e.keyCode), matches = [];
            angular.forEach(scope.validValues, function(value, key){
              if(char === value) matches.push(char);
            }, matches);
            if(matches.length == 0){
              e.preventDefault();
              return false;
            }
          });
        }
    }   
});