NG-变化获得新的价值和原始值 [英] ng-change get new value and original value

问题描述

我使用的是NG-选项可供选择下拉值。我希望能够在旧值进行比较，以新的价值。 NG-变化可以很好地用于抓拉的新的价值了，但我怎么能得到两个新的价值与原价值？

I'm using ng-options to select values from a pulldown. I'd like to be able to compare the old value to the new value. ng-change works well for grabbing the new value of the pull down, but how can I get both the new value and the original value?

<select ng-change="updateValue(user)" ng-model="user.id" ng-options="user.id as user.name for user in users"></select> 

例如，假设我想控制器日志，你以前user.name是比尔，你当前的用户名是PHILLIPE。

For instance, let's say I wanted the controller to log, "Your former user.name was BILL, your current user name is PHILLIPE."

推荐答案

通过角{{EX pression}}您可以添加老用户或user.id价值的NG-改变属性为文字字符串

With an angular {{expression}} you can add the old user or user.id value to the ng-change attribute as a literal string:

<select ng-change="updateValue(user, '{{user.id}}')" 
        ng-model="user.id" ng-options="user.id as user.name for user in users">
</select>

在ngChange，第一参数updateValue将是新的用户价值，第二个参数将是在选择标签最近一次被更新的角度，与老user.id值形成文字。

On ngChange, the 1st argument to updateValue will be the new user value, the 2nd argument will be the literal that was formed when the select-tag was last updated by angular, with the old user.id value.

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