7

我想根据具有一个或多个参数的函数的返回值在按钮上设置启用属性。我怎样才能做到这一点？

private function isUserAllowed (userName:Boolean):Boolean {
   if (userName == 'Tom')
      return true;
   if (userName == 'Bill')
      return false;
}

<mx:Button label="Create PO" id="createPOButton"
enabled="<I want to call isUserAllowed ('Bill') or isUserAllowed ('Tom') here>"
click="createPOButton_Click()" />
4

4 回答 4

10

根据 Flex docs，只要属性是可绑定的，您就可以简单地执行此操作（我已经包含了两个额外的按钮来演示）：

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute">

    <mx:Script>
        <![CDATA[

            [Bindable]
            private var currentUser:String = "Bill";

            private function isUserAllowed(user:String):Boolean
            {
                if (user == "Bill")
                {
                    return true;
                }

                return false;
            }

        ]]>
    </mx:Script>

    <mx:VBox>
        <mx:Button label="My Button" enabled="{isUserAllowed(currentUser)}" />
        <mx:HBox>
            <mx:Button label="Try Tom" click="{currentUser = 'Tom'}" />
            <mx:Button label="Try Bill" click="{currentUser = 'Bill'}" />
        </mx:HBox>
    </mx:VBox>

</mx:Application>

但是，如果没有将 currentUser 标记为 [Bindable]，它将无法工作。

另一种方法是，如果您想更直接地绑定到函数（这也在文档中表达），则让函数响应您在当前用户更改时调度的事件，如下所示：

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" initialize="init()">

    <mx:Script>
        <![CDATA[

            private var _currentUser:String = "Bill";

            public function set currentUser(value:String):void
            {
                if (_currentUser != value)
                {
                    _currentUser = value;
                    dispatchEvent(new Event("userChanged"));
                }
            }           

            [Bindable(event="userChanged")]
            private function isUserEnabled():Boolean
            {
                if (_currentUser == "Bill")
                {
                    return true;
                }

                return false;
            }

        ]]>
    </mx:Script>

    <mx:VBox>
        <mx:Button label="My Button" enabled="{isUserEnabled()}" />
        <mx:HBox>
            <mx:Button label="Try Tom" click="{currentUser = 'Tom'}" />
            <mx:Button label="Try Bill" click="{currentUser = 'Bill'}" />
        </mx:HBox>
    </mx:VBox>

</mx:Application>

所以有几种方法。IMO，第二个似乎更合适，但第一个绝对没有错。祝你好运！

于 2009-01-15T04:42:37.377 回答
7 
<mx:Button
enabled = "{this.myFunction(this.myVariable)}"
>

或内联：

<mx:Button
enabled = "{(function(arg:Object):Boolean{ ... })(this.myVariable)}"
>
于 2009-01-15T15:17:28.203 回答
2

这是我在类似情况下所做的几次：

<mx:Script>
<![CDATA[

    [Bindable] var _username : String;

    private function isUserAllowed (userName:Boolean):Boolean {
        if (userName == 'Tom')
            return true;
        if (userName == 'Bill')
            return false;
    }

]]>
</mx:Script>

<mx:Button label="Create PO"
    id="createPOButton"
    enabled="{isUserAllowed(_username)}"
    click="createPOButton_Click()" />

这样，当 Bindable_username更改时，它将触发更改通知。由于标签正在监听_username变化（即使它只是另一个函数的参数），该enabled属性将被重新评估。

于 2009-01-15T02:08:01.557 回答
0 
<mx:Script>
    <![CDATA[
        [Bindable]
        private var userName : String = "Tom"; // or whatever ...
        [Bindable]
        private var userAllowed : Boolean;

        private function isUserAllowed ():Boolean {
           if (userName == 'Tom')
             return false;
           if (userName == 'Bill')
              return false;
           return false;
        }
    ]]>
</mx:Script>

    <mx:Button label="Create PO" id="createPOButton" enabled="{userAllowed}" addedToStage="isUserAllowed()"/>
于 2009-01-15T01:46:28.060 回答