Angular JS directive, change a 2 way data binding in the link function

angularjs, javascript

Solution

If you don't pass the two way data binding, angular gets angry:

https://github.com/angular/angular.js/issues/1435

Use optional binding (=?):

app.directive('testElement', [function () {
    return {
        restrict: "E",
        scope: {
            options: "=?"
        },
        template: "<p><span>Name: </span>{{ options.name }}{{ test }}</p>",
        link: function (scope, element, attrs) {
            scope.options = scope.options || {};
            if (attrs.name)
                scope.options.name = attrs.name;
        }
    };
}]);

Or if you are using an older version of angular, use $eval on attrs. options:

app.directive('testElement', [function () {
    return {
        restrict: "E",
        //Still can create isolate scope to not clobber parent scope variables.
        scope: {},
        template: "<p><span>Name: </span>{{ options.name }}{{ test }}</p>",
        link: function (scope, element, attrs) {
            scope.options = scope.$eval(attrs.options) || {};
            if (attrs.name)
                scope.options.name = attrs.name;
        }
    };
}]);

Problem

I'm trying to create an angular directive where I can set the options either via a single options object, or via some attributes. Here is an example of the kind of code: ``` app.directive('testElement', [function () { return { restrict: "E", scope: { options: "=" }, template: "<p><span>Name: </span>{{ options.name }}</p>", link: function (scope, element, attrs) { scope.options = scope.options || {}; if (attrs.name) scope.options.name = attrs.name; } }; }]); ``` This works fine, in that the name value is displayed if I pass in a name via the options attribute. But if I pass a name via the name attribute, even though the link function does modify options, the value is not rendered. http://plnkr.co/edit/IMVZRdAW2a5HvSq2WtgT?p=preview I feel like I'm missing something fundamental in how the 2 way data binding of options works.

Original source