Good way to dynamically open / close a popover (or tooltip) using angular, based on expression?

Question

I have a form that is wired into angular, using it for validation. I am able to display error messages using ng-show directives like so:

Answer 1

From Michael Stramel's answer, but with a full angularJS solution:

// define additional triggers on Tooltip and Popover
app.config(['$tooltipProvider', function($tooltipProvider){
    $tooltipProvider.setTriggers({
       'show': 'hide'
    });
}])

Now add this directive:

app.directive('ntTriggerIf', ['$timeout',
function ($timeout) {
    /*
    Intended use:
        

    */
    return {

        restrict: 'A',
        link: function (scope, element, attrs) {

            attrs.$observe('ntTriggerIf', function (val) {
                try {

                    var ob_options = JSON.parse(attrs.ntTriggerIf.split("'").join('"') || "");
                }
                catch (e) {
                    return
                }

                $timeout(function () {
                    for (var st_name in ob_options) {
                        var condition = ob_options[st_name];
                        if (condition) {
                            element.trigger(st_name);
                        }
                    }
                })

            })
        }
    }
}])

Then in your markup: