在角度指令中完成 ng-repeat

问题描述

在下面的代码中，angular 指令myscroll"如何知道正在创建什么 ng-repeat 元素?

In the code below, how does the angular directive 'myscroll' know what ng-repeat elements are being created?

<myscroll>
     <div ng-repeat="a in arr">{{a}}</div>
</myscroll>

我知道 $last 事件没有被触发到父指令，我该如何解决这个问题?

I know that the $last event is not fired to the parent directive, how can I solve this?

myapp.directive("myscroll", function () {
    return{
        restrict: "E",
        transclude: true,
        template: "<span class='left'></span><div class='mask' ng-transclude></div><span class='right'></span>",
        link: function (scope, element, attr) {

            scope.$watch("$last",function(){ console.log("ng-repeat rendered") })

        }
    }
})

推荐答案

为了防止其他人偶然发现这个问题，我想分享我的解决方案.dluz 的回答为我指明了正确的方向，但我采取了更优雅"的方法.

Just in case someone else stumbles upon this question, I wanted to share my solution. dluz's answer pointed me in the right direction, but I took a more 'elegant' approach.

为了给你提供上下文，我需要使用这个系统和 ng-repeat 来填充选择下拉列表中的选项.ng-options 与 jQuery Chosen 插件(漂亮的自动完成/搜索下拉插件，由方式！)，我需要在所有选项都完成渲染后初始化插件.

To give you context, I needed to use this system with ng-repeat to populate the options in a select dropdown. There was an incompatibility with ng-options with the jQuery Chosen plugin (beautiful autocomplete/search dropdown plugin, by the way!), and I needed to initialize the plugin once all the options were finished rendering.

HTML:

<select auto-complete ng-model="stuff">
    <option ng-repeat="item in items" value="{{ item.value }}">{{ item.name }}</option>
</select>

JavaScript:

JavaScript:

// Extension of built-in ngRepeat directive - broadcasts to its parent when it is finished.
// Passes the last element rendered as an event parameter.
app.directive('ngRepeat', function () {
    return {
        restrict: 'A',
        link: function ($scope, $elem, $attrs) {
            if ($scope.$last)
                $scope.$parent.$broadcast('event:repeat-done', $elem);
        }
    };
});

// My directive for working with the Chosen plugin.
app.directive('autoComplete', function () {
    return {
        restrict: 'A',
        link: function ($scope, $elem, $attrs) {
            $scope.$on('event:repeat-done', function () {
                setTimeout(function () {
                    if (!$elem.children(':first-child').is('[disabled]'))
                        $elem.prepend('<option disabled="disabled"></option>');
                    $elem.chosen({ disable_search_threshold: 10, width: '100%' });
                    $elem.trigger('chosen:updated');
                });
            });
        }
    };
});

如您所见，我只是使用广播功能扩展了内置的 ng-repeat 指令.由于这是一个非侵入性的添加，我毫不犹豫地将其应用到 ng-repeat 的所有用途中.

As you can see, I simply extended the built-in ng-repeat directive with my broadcaster function. Since it's a non-invasive addition, I have no qualms with implementing this into all uses of ng-repeat.

在函数本身中，我使用 Angular 的 $scope，而不是查看 $elem.parent().scope()(这可以 - 而且在大多数情况下可以 - 工作).$parent 获取父上下文.

Within the function itself, instead of looking at $elem.parent().scope() (which could - and in most situations would - work), I use Angular's $scope.$parent to fetch the parent context.

然后我广播一个自定义事件(event:repeat-done)，并将最后呈现的重复元素作为参数传递给父作用域.

Then I broadcast a custom event (event:repeat-done), and pass the last rendered repeat element as a parameter to the parent scope.

然后我可以在我的自动完成指令中选择这个事件并在完全渲染的 select 元素上初始化我的 Chosen 插件！

I could then pick up this event in my auto-complete directive and initialize my Chosen plugin over the fully-rendered select element!

这种技术可以普遍应用于您需要检测何时完成 ng-repeat 指令的任何时间.例如:

This technique could then be generically applied to any time you need to detect when an ng-repeat directive is done. For your example:

myapp.directive("myscroll", function () {
    return{
        restrict: "E",
        transclude: true,
        template: "<span class='left'></span><div class='mask' ng-transclude></div><span class='right'></span>",
        link: function (scope, element, attr) {
            scope.$on("event:repeat-done",function(){ console.log("ng-repeat rendered") })
        }
    }
})

对于某些情况，在 rootScope 上一直检测这些事件可能是有益的.如果是这种情况，您可以将 $scope.$parent.$broadcast 替换为 $scope.$emit 以使事件向上冒泡而不是向下冒泡.

For some cases it may be beneficial to detect these events all the way up at the rootScope. If this is the case, you could replace $scope.$parent.$broadcast with $scope.$emit to have the event bubble up instead of down.

这篇关于在角度指令中完成 ng-repeat的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！