当从聚焦输入按下回车键时，ng-submit不起作用

Question

出于某种原因，当我在取消隐藏输入后按Enter键时，submit_form()函数无法运行。有没有人对为什么这不起作用有任何想法？

<form name="theform" ng-submit="submit_form()" novalidate>

        <div ng-hide="show_form">
            <div ng-click="show_input()">Click me</div>
        </div>

        <div ng-show="show_form">
            <input type="text" class="md_input" ng-model="inputstuff" placeholder="name" required />   
        </div>

</form>

内部控制器：

$scope.show_form = false;
$scope.show_input = function() { $scope.show_form = true; }
$scope.submit_form = function() { console.log("TRIGGER"); }