Example of a directive using parsers and formatters

a-simple-parser.js

ngModel.$parsers.push(function(value){
    value.toUpperCase();
    return value;
});

controller-function.js

$scope.change_model = function(){
  $scope.some_letters = {value: 'dave'};
};

controller.js

$scope.some_letters = {value:'alex'};

directive.js

app.directive('changeCase', function(){
    return{
        restrict: 'A',
        templateUrl: 'scripts/directives/directive_templates/directive.html',
        require: 'ngModel',
        link: function(scope, element, attr, ngModel){
            
            ngModel.$formatters.push(function(value){

            });

            ngModel.$parsers.push(function(value){

            });

        }
    };
});

markup.html

<form role="form" name="myform">
    <div class="form-group">
        <label>View Value:</label>
        <input name="someinput" changecase="" ng-model="some_letters.value">
    </div>
</form>

<strong>ModelValue:</strong>  {{some_letters.value}} <br>

more-complex-parser.js

var view_value;
ngModel.$parsers.push(function(value){

    var return_value;

    if(value.length > 5){
        return_value = view_value;
        ngModel.$setViewValue(view_value);
        ngModel.$render();
        ngModel.$setValidity('is_valid', false);
    } else {
        return_value = value;
        view_value = return_value;
        ngModel.$setValidity('is_valid', true);
    }

    return return_value;
});

simple-formatter.js

ngModel.$formatters.push(function(value){
    value.toUpperCase();
    return value;
});