如何限制自定义指令的可能属性值？

Question

Currently I am trying:

module.directive('myDirective', function() {
    return {
        scope: { foo: '@' },
        template: '{{foo}}',
        link: function(scope) {
            if (scope.foo != 'first' && scope.foo != 'second')
              throw new Error("Only values 'first' and 'second' allowed for attribute 'foo' of myDirective");
        }
    };
});

But is there a "more angular" way?

Answer 1

When you have a set of values (like enums) that could be passed to the directive, you should make this set available to the controller as well as to the directive.

For example, if you can only pass certain colors, you should create a color constant and inject this constant in the controller as well as in the directive. From the controller you pass it to the directive and in the directive you check against the color constant collection.

I don't think you can make the check itself easier, or more like the 'angular way'. You could however create a factory method that checks if the color is a valid color from the constant for example.