AngularJS directive: Check if attribute is assignable

Question

I'm trying to implement an AngularJS directive that takes attribute-flag selected, which indicates initial state + any current value, if it is assignable.

How can I implement a verification in AngularJS directive to see that the attribute is assignable, before setting a value in it?

app.directive('customControl', [function () {
    return {
        restrict: 'E',
        scope: {
            selected: '=?', // optional, initial + current selected state;
        },
        templateUrl: 'views/directives/customControl.html',
        link: function (scope, elem, attr) {
            if (/* scope.selected is assignable */) {
                scope.selected = /* some value */;
            }
        }
    };
}]);

New Dev · Accepted Answer · 2015-05-12 12:11:01Z

1

You could use the $parse service for that:

link: function(scope){
    var selectedGet = $parse(attrs.selected);
    var selectedSet = selectedGet.assign;

    // etc...

    if (selectedSet){
      selectedSet(scope.$parent, obj);
    }
}

edited May 12, 2015 at 12:11

answered May 12, 2015 at 11:46

New Dev

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4 Comments

vitaly-t Over a year ago

I have tried using try/catch, it didn't work, the exception still propagates outside the catch block.

New Dev Over a year ago

@vitaly-t, yeah, you're right - it wouldn't catch it... I'll remove it

vitaly-t Over a year ago

Why use selectedSet(scope, obj) instead of scope.selected = value? I have tried the latter first, and it worked.

New Dev Over a year ago

@vitaly-t, either way would work in your case, but the former approach works even if you didn't have an isolate scope. Actually, it should be scope.$parent

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