javascript - Two way data binding in AngularJS Directives

Question

I have been trying to define directives so I can display different "widgets" in a form, depending on the type of field and its parameters, which are stored in a database. I need to react to different types of scenarios, hence the need for directives to handle layout.

While playing with a few examples, I came up with a code that *kinda* works:

HTML

<input type="text" ng-model="myModel" style="width: 90%"/>  
<div class="zippy" zippy-title="myModel"></div>

Directive

myApp.directive('zippy', function(){
    return {
      restrict: 'C',
      // This HTML will replace the zippy directive.
      transclude: true,
      scope: { title:'=zippyTitle' },
      template: '<input type="text" value="{{title}}"style="width: 90%"/>',
      // The linking function will add behavior to the template
      link: function(scope, element, attrs) {
            // Title element
            element.bind('blur keyup change', function() {
                scope.$apply(read);
            });

            var input = element.children();


            function read() {
                scope.title = input.val();
            }
        }
    }
});

This seems to works (albeit noticeably slower than a *proper* angularJS variable binding) but I figure there must be a better way to do this. Can anyone shed some light on the matter?

Answer 1

I don't know why you are triggering the $apply method manually because you actually don't need it.

I edited the example you used from the Angular page and included the input. It works for me: http://jsfiddle.net/6HcGS/2/

HTML

<div ng-app="zippyModule">
  <div ng-controller="Ctrl3">
    Title: <input ng-model="title">
    <hr>
    <div class="zippy" zippy-title="title"></div>
  </div>
</div>?

JS

function Ctrl3($scope) {
  $scope.title = 'Lorem Ipsum';
}

angular.module('zippyModule', [])
  .directive('zippy', function(){
    return {
      restrict: 'C',
      replace: true,
      transclude: true,
      scope: { title:'=zippyTitle' },
      template: '<input type="text" value="{{title}}"style="width: 90%"/>',
      link: function(scope, element, attrs) {
        // Your controller
      }
    }
  });

UPDATE maxisam is right, you have to use ng-model instead of binding the variable against the value like so:

<input type="text" ng-model="title" style="width: 90%"/>

Here is the working version: http://jsfiddle.net/6HcGS/3/