是什么value`属性和`在angularjs NG-value`属性之间`的区别 [英] What is the difference between `value` attribute and `ng-value` attributes in angularjs

问题描述

什么是值和 NG-值在angularjs模板属性之间的区别？如果我用值中使用 NG-IF 场上属性它工作正常，但如果我更改属性值到 NG-值将停止工作。

 例如1 //它的工作原理＆LT;输入类型='无线电'NG-模式='困难'值='硬'/＆GT;
＆LT; D​​IV NG-IF =难度=='硬'＆GT;
     ＆所述p为H.;困难是硬下; / P＆GT;
＆LT; / DIV＆GT;例2 //这是行不通的＆LT;输入类型='无线电'NG-模式='级别'NG值='硬'/＆GT;
＆LT; D​​IV NG-IF =级=='硬'＆GT;
     ＆所述; P＆gt;级是硬下; / P＆GT;
＆LT; / DIV＆GT;
 

解决方案

据 的文档 ， ngValue 需要一个的角前pression，其价值将被绑定到值的输入元素的属性的

所以，当你使用 NG-值=硬，这是PTED作为一个前pression和值势必 $ scope.hard （这可能是未定义）< BR>
ngValue 是评估前pressions有用 - 它没有优势值设置硬codeD值。然而，如果你想用硬 ngValue codeA值，则必须将其括在：

  NG-值='硬'
 

What is the difference between value and ng-value attributes in angularjs templates? If I use ng-if on the field using value attribute it works properly but if I change the attribute value to ng-value it stops working.

example 1  // it works 

<input type='radio' ng-model='difficulty' value='hard'/>
<div ng-if="difficulty == 'hard'">
     <p>difficulty is hard</p>
</div>  

Example 2 // it doesn't work

<input type='radio' ng-model='level' ng-value='hard'/>
<div ng-if= "level == 'hard'" >
     <p>level is hard</p>
</div>

解决方案

According to the docs, ngValue takes an "angular expression, whose value will be bound to the value attribute of the input element".

So, when you use ng-value="hard", it is interpreted as an expression and the value is bound to $scope.hard (which is probably undefined).
ngValue is useful for evaluating expressions - it has no advantage over value for setting hard-coded values. Yet, if you want to hard-code a value with ngValue, you must enclose it in '':

ng-value="'hard'"

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