可选的双向对角分离指令约束范围 [英] Optional two-way binding on isolate scope for Angular Directive
问题描述
我刚刚得知你可以有一个可选的反向或回调结合通过：
I just learned that you can have an optional 'reverse' or callback binding via:
scope: { parentScopeFunc: '&?' }
我想看看是否有一种方法做的2路绑定类似的东西。
I'm trying to see if there is a way to do something similar with the 2-way binding.
scope: { optional2WayBoundProp: '=?' }
我试图与连接功能的元素＆安培; ATTRS PARAMS但后来我失去了2路结合回父。该方法只允许父母对子女的更新。然后，我可能也仅仅使用 @ 范围的机制。
I tried with the link function's element & attrs params but then I lose the 2-way-binding back to the parent. That method only allows for parent-to-child updates. Then I might as well just be using @ scope mechanism.
我发现这个问题，<一个href=\"http://stackoverflow.com/questions/22665363/angular-js-directive-change-a-2-way-data-binding-in-the-link-function\">Angular JS指令，改变一个2路数据链接功能绑定，这样回答关于主要问题 = <？/ code>。然而，它并没有解决可选非绑定的值，如真正或假。
I found this question Angular JS directive, change a 2 way data binding in the link function so that answers the main question regarding =?. However it doesn't solve the 'optional' non-bound value such as true or false.
下面就是我要完成的：
-
编写transcludes内容，并可折叠除了标题区面板指令：
＆LT;我-面板＆gt;
＆LT; transcluded头内容/＆GT;
＆LT;按钮NG点击=toggleCollapse（）/＆GT;
＆LT; transcluded体内容NG-IF =isExpanded/＆GT;
＆LT; /我-面板＆gt;
在某些情况下，我想缓存在父范围面板实例的折叠状态（因此2路结合，其视图的控制器可以决定如何缓存此信息）：
＆LT;我的面板被展开=parentScopeProp＆GT;
in some cases I want to cache the collapsed state of the panel instance in a parent scope (hence the 2-way binding where the view's controller can determine how to cache this info):
<my-panel is-expanded="parentScopeProp">
据我了解，通过使用 = 分配，即前pressions像未定义，真正＆安培; 假无法评估。
I understand that by using the = assignment, that expressions like undefined, true & false cannot be evaluated.
推荐答案
=？是一个有效的范围分配为NG 1.2.x版本的...
'=?' is a valid scope assignment as of ng 1.2.x...
...至于有从可选的双向结合插值的前pression手段的能力，这是仍待价而沽。
...as for the ability to have a means of interpolating an expression from an optional two-way-binding, that is still up for grabs.
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