AngularJS - 有条件地使用属性指令 [英] AngularJS - Use attribute directive conditionally

问题描述

我使用draggable"指令来支持图像拖动.但是，根据用户的角色，我需要为某些用户组禁用图像拖动.我使用了以下代码.

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> 

方法 dragSupported 在模板范围内并返回 true 或 false.我不想通过对 dragSupported() 返回的每个值使用 ng-if 来创建两个大的重复

元素.换句话说，我不是在寻找以下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>

还有其他方法可以避免代码重复吗?

Is there any other approach to avoid code duplicity?

推荐答案

ng-attr-

支持有条件地声明 HTML 属性作为动态标题的 ng-attr-<attrName> 指令包含在 Angular 中.

ng-attr-<attrName>

Support for conditionally declaring an HTML attribute is included with Angular as the dynamically-titled ng-attr-<attrName> directive.

ng-attr 的官方文档

在您的情况下，代码可能如下所示:

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>

演示

JSFiddle

这包含以下值的使用示例:true、false、undefined、null、1、0 和 "".请注意通常错误的值可能会产生意想不到的结果.

This 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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