如何将范围中的变量注入Angular控制器？

Question

In index.html , I am doing something like this:

<div ng-controller="MyController">
    <div ng-model="pk" ng-init="pk='2'"></div>
</div>

Anyway, in my angular file, I am doing something like this:

.controller('MyController', [
  '$scope', function($scope) {
    alert('Sup ' + $scope.pk);
  }
])

So lets say the pk for a URL is 2, I expect to see something like this:

Sup 2

However, my output is this :

Sup undefined

What am I doing wrong? Thanks!

Answer 1

This happens, because code from controller execute before code from view, so when run

alert('Sup ' + $scope.pk);

ng-init - not execute.

So, for solution, you can simple assign value inside controller, or use solution from other answers like watch , or timeout

Answer 2

Delay the alert with $timeout :

.controller('myCtrl', [
  '$scope', '$timeout', function($scope, $timeout) {
    $timeout(function() 
      alert('Sup ' + $scope.pk);
    });
  }
]);

Answer 3

Use $scope.$watch :

.controller('MyController', ['$scope', function($scope) {
    $scope.$watch('pk', function(newValue, oldValue) {
        alert('Sup ' + newValue);
    });
}]);

Your alert('Sup ' + $scope.pk); is called before the view has been initialized and therefore before ng-init is called.

Answer 4

Angular has a trick that should always be followed: "Always use a dot in models". For example:

ng-model="models.pk"

See more in this answer .

You should also consider following some guidelines from John Papa that prevent that kind of problems, see here one example. Try it and tell me how it went.