角 - 使用属性指令有条件 [英] Angular - Use attribute directive conditionally

问题描述

我使用拖动指令，支持图像拖动。然而，根据用户的角色，我需要禁用图像拖动为某些用户组。我用下面的code。

I am using "draggable" directive to support image dragging. However, as per the role of the user, I need to disable image dragging for certain groups of users. I have used following code.

<!--draggable attribute is used as handle to make it draggable using jquery event-->           
<li  ng-repeat="template in templates" draggable id="{{template._id}}" type="template" class="template-box">            
<!-- Images and other fields are child of "li" tag which can be dragged.-->                    
</li> 

该方法 dragSupported 是模板范围和回报真正或假。我不想创建两大副本＆LT;李＆GT; 使用元素 NG-如果为每个值返回通过 dragSupported（）。换句话说，我不找下面的方法来解决这个问题。

The method dragSupported is in the template scope and returns true or false. I don't want to create two big duplicate <li> elements by using ng-if for each value returned by dragSupported(). In other words, I am not looking for the following approach to solve this.

<!--draggable attribute is used as handle to make it draggable using jquery event-->           
<li ng-if="dragSupported() ==true"  ng-repeat="template in templates" draggable id="{{template._id}}" type="template" class="template-box">            
<!-- Images and other fields are child of "li" tag which can be dragged.-->                    
</li>
<!--remove "draggable" directive as user doesn't have permission to drag file -->
<li ng-if="dragSupported() !=true"  ng-repeat="template in templates"  id="{{template._id}}" type="template" class="template-box">            
<!-- Images and other fields are child of "li" tag which can be dragged.-->                    
</li>

是否有任何其他的方法来避免code口是心非？

Is there any other approach to avoid code duplicity?

推荐答案

的jsfiddle

此功能来包装的角作为动态题为 NG-attr-＆LT; attrName＆GT; 指令。在你的情况下，code可能是这样的：

This functionality comes packaged with Angular as the dynamically-titled ng-attr-<attrName> directive. In your case, the code might look like this:

<li
    id="{{template._id}}"
    class="template-box"
    type="template"
    ng-repeat="template in templates"
    ng-attr-draggable="dragSupported() === true"
></li>

借助的jsfiddle 包含用法示例以下值：真正，假，未定义，空， 1 ， 0 和，。请注意，通常falsey值可能产生怎样意想不到的效果。

The JSFiddle contains examples of usage for the following values: true, false, undefined, null, 1, 0, and "". Note how typically-falsey values may yield unexpected results.

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