angularjs - 错误 : [ngModel:nonassign] Expression is non-assignable

Question

尝试根据同一行中的另一个值显示来自 gridcollection 的列值。
用户可以在包含带有值的网格的模式中选择/更改值。当模式关闭时，值将被传回。那时我想为“也称为”设置一个值:

html:

 Also known as: <input type="text" `ng-model="displayValue(displayNameData[0].show,displayNameData[0].value)">`

我在范围上创建了一个函数，仅当“显示”值为真时才选择该值:

$scope.displayValue = function (show, val) {
    if (show) {
        return val;
    }
    else {
        return '';
    }
}

但是，当我关闭模式时，出现错误:

Error: [ngModel:nonassign] Expression 'displayValue(displayNameData[0].show,displayNameData[0].value)' is non-assignable. 

plnkr 引用: http://plnkr.co/edit/UoQHYwAxwdvX0qx7JFVW?p=preview

Answer 1

You can bind ng-model to function

Binding to a getter/setter
Sometimes it's helpful to bind ngModel to a getter/setter function. A getter/setter is a function that returns a representation of the model when called with zero arguments, and sets the internal state of a model when called with an argument. It's sometimes useful to use this for models that have an internal representation that's different from what the model exposes to the view.

索引.html

<div ng-controller="ExampleController">
  <form name="userForm">
    <label>Name:
      <input type="text" name="userName"
             ng-model="user.name"
             ng-model-options="{ getterSetter: true }" />
    </label>
  </form>
  <pre>user.name = <span ng-bind="user.name()"></span></pre>
</div>

应用程序.js

angular.module('getterSetterExample', [])
.controller('ExampleController', ['$scope', function($scope) {
  var _name = 'Brian';
  $scope.user = {
    name: function(newName) {
     // Note that newName can be undefined for two reasons:
     // 1. Because it is called as a getter and thus called with no arguments
     // 2. Because the property should actually be set to undefined. This happens e.g. if the
     //    input is invalid
     return arguments.length ? (_name = newName) : _name;
    }
  };
}]);