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我正在学习“一周内的 Flex”教程,我已经达到了他们在 Flex 中实现 MVC 模型的地步。在那之前一切都很好,但在视图中,他们使用 dropDownList 连接到 dataProvider 并保留 selectedIndex 未声明(默认为 -1)。我(想聪明点!)尝试设置 selectedIndex = 0 或 1 或任何其他数字。但是什么都没有发生,我怎么能这样做?

课程详情在这里:

http://www.adobe.com/devnet/flex/videotraining/exercises/ex2_06.html

在我看来,代码的重要部分是:

主应用:

创建数组:

            [Bindable]
            private var employees:ArrayCollection = new ArrayCollection();

这个数组填充了来自 httpservice 的日期:

                for each (var emp:Object in employeeData) 
                {
                    employee = new Employee();
                    employee.firstName = emp.firstName;
                    employee.lastName = emp.lastName; 
                    employee.id = emp.id; 
                    employee.title = emp.title; 
                    employee.email = emp.email; 
                    employee.managerID = emp.managerID; 
                    employee.department = emp.department; 
                    employee.location = emp.location; 
                    employee.deskLocation = emp.deskLocation; 
                    employee.city = emp.city; 
                    employee.state = emp.state; 
                    employee.countryCode = emp.countryCode; 
                    employee.postalCode = emp.postalCode; 
                    employee.directDial = emp.directDial; 
                    employee.hireDate = emp.hireDate; 
                    employee.evaluation = emp.evaluation; 
                    employee.phone = emp.phone;
                    employees.addItem(employee);
                }

以数组形式传递给自定义组件:

    <components:VehicleRequestForm employees="{employees}"/>

这个自定义表单捕获它并放入一个 dropDownList,但 selectedIndex 似乎不起作用,它仍然默认为 -1。我怎样才能解决这个问题?(赞赏所有理想):

        <s:FormItem label="Employee:">
            <s:DropDownList id="dropDownList"
                            dataProvider="{employees}"
                            labelField="lastName"
                            selectedIndex="1"/>
        </s:FormItem>

        <s:FormItem label="Office Phone:">
            <s:TextInput id="phone"
                         text="{dropDownList.selectedItem.phone}"/>

ex2_08_solutions.mxml:

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
               xmlns:s="library://ns.adobe.com/flex/spark" 
               xmlns:mx="library://ns.adobe.com/flex/mx" 
               minWidth="955" minHeight="850"
               creationComplete="employeeService.send()" 
               xmlns:components="components.*">

    <!-- Exercise 2.08: Creating an ArrayCollection of value objects -->

    <!-- Styles ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->

    <fx:Style source="Styles.css"/>

    <!-- Script ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->

    <fx:Script>
        <![CDATA[
            import mx.collections.ArrayCollection;
            import mx.controls.Alert;
            import mx.rpc.events.FaultEvent;
            import mx.rpc.events.ResultEvent;

            import valueObjects.Employee;

            // variable declarations ------------------------------------

            [Bindable]
            private var employees:ArrayCollection = new ArrayCollection();

            // getter/setters -------------------------------------------


            // helper methods -------------------------------------------


            // event handlers -------------------------------------------

            protected function employeeService_resultHandler(event:ResultEvent):void
            {
                var employeeData:ArrayCollection = event.result.employees.employee;
                var employee:Employee;

                for each (var emp:Object in employeeData) 
                {
                    employee = new Employee();
                    employee.firstName = emp.firstName;
                    employee.lastName = emp.lastName; 
                    employee.id = emp.id; 
                    employee.title = emp.title; 
                    employee.email = emp.email; 
                    employee.managerID = emp.managerID; 
                    employee.department = emp.department; 
                    employee.location = emp.location; 
                    employee.deskLocation = emp.deskLocation; 
                    employee.city = emp.city; 
                    employee.state = emp.state; 
                    employee.countryCode = emp.countryCode; 
                    employee.postalCode = emp.postalCode; 
                    employee.directDial = emp.directDial; 
                    employee.hireDate = emp.hireDate; 
                    employee.evaluation = emp.evaluation; 
                    employee.phone = emp.phone;
                    employees.addItem(employee);
                }

            }

            protected function employeeService_faultHandler(event:FaultEvent):void
            {
                Alert.show(event.fault.faultString,"Fault Information");    
            }

        ]]>
    </fx:Script>

    <!-- Declarations ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->

    <fx:Declarations>

        <s:HTTPService id="employeeService"
                       url="http://adobetes.com/f45iaw100/remoteData/employees.xml"
                       result="employeeService_resultHandler(event)"
                       fault="employeeService_faultHandler(event)"/>

    </fx:Declarations>

    <!-- UI components ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->

    <s:Label x="10" y="34" 
             width="690" height="40" 
             text="Employee Portal: Vehicle Request Form"
             styleName="titleHeader"/>

    <components:VehicleRequestForm employees="{employees}"/>

</s:Application>

VehicleRequestForm.mxml:

<?xml version="1.0" encoding="utf-8"?>
<s:Group xmlns:fx="http://ns.adobe.com/mxml/2009" 
         xmlns:s="library://ns.adobe.com/flex/spark" 
         xmlns:mx="library://ns.adobe.com/flex/mx"
         creationComplete="init()">

    <!-- Styles ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->



    <!-- Script ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->

    <fx:Script>
        <![CDATA[

            // import statements ----------------------------------------

            import mx.collections.ArrayCollection;
            import mx.controls.Alert;
            import mx.events.CalendarLayoutChangeEvent;

            // variable declarations ------------------------------------

            [Bindable]
            public var employees:ArrayCollection;

            // getter/setters -------------------------------------------


            // helper methods -------------------------------------------


            // event handlers -------------------------------------------

            private function dateChangeHandler(event:CalendarLayoutChangeEvent):void
            {
                Alert.show('You have selected ' + event.target.selectedDate.toDateString());

                if ((event.target.id == "returnDate") && (pickupDate.selectedDate > returnDate.selectedDate)) 
                {
                    Alert.show("Pickup date must be scheduled before return date.");
                }

                if ((event.target.id == "pickupDate") && (pickupDate.selectedDate > returnDate.selectedDate) && (returnDate.selectedDate != null)) 
                {
                    Alert.show("Pickup date must be scheduled before return date.")
                }

            }

            private function init():void
            {
                pickupDate.addEventListener(CalendarLayoutChangeEvent.CHANGE, dateChangeHandler);
                returnDate.addEventListener(CalendarLayoutChangeEvent.CHANGE, dateChangeHandler);
            }

        ]]>
    </fx:Script>

    <!-- Declarations ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->

    <fx:Declarations>
        <!-- Place non-visual elements (e.g., services, value objects) here -->
    </fx:Declarations>

    <!-- UI components ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->

    <s:Form x="10" y="70">

        <s:FormItem label="Employee:">
            <s:DropDownList id="dropDownList"
                            dataProvider="{employees}"
                            labelField="lastName"
                            selectedIndex="1"/>
        </s:FormItem>

        <s:FormItem label="Office Phone:">
            <s:TextInput id="phone"
                         text="{dropDownList.selectedItem.phone}"/>
        </s:FormItem>

        <s:FormItem label="Mobile Phone:">
            <s:TextInput id="mobilePhone"/>
        </s:FormItem>

        <s:FormHeading label="Dates Requested"/>

        <s:FormItem label="Pickup Date:">
            <mx:DateChooser id="pickupDate"/>
        </s:FormItem>

        <s:FormItem label="Return Date:">
            <mx:DateChooser id="returnDate"/>
        </s:FormItem>

        <s:FormItem>
            <s:Button id="submitButton" 
                      label="Submit Request"/>
        </s:FormItem>

    </s:Form>

</s:Group>
4

2 回答 2

1

您不能设置selectedIndex为不在dataProvider. 当您DropdownList被实例化时,dataProvider是一个空集合,因此 1 不是有效的选定索引。

selectedIndex填充集合后尝试设置您的。您可能需要这样做callLater(通常不是立即处理数据,而是在帧结束时处理数据。对于某些组件,这非常重要,对于其他组件,您可以忽略它)。

如果您只需要强制选择,请尝试设置requireSelectiontrue.

更新(如何使用callLater)

protected function employeeService_resultHandler(event:ResultEvent):void{
            //...populating dataprovider

            callLater(function():void{
                if(dropDownList.dataProvider.length > wantedIndex){
                    dropDownList.selectedIndex=wantedIndex;
                }else{
                    Alert.show('can\'t select necessary index!','error')
                }
            });
}
于 2013-07-27T10:41:13.407 回答
0

你可以试试这个

<s:DropDownList requireSelection="true" />

如果为 true,则必须始终在控件中选择数据项。如果值为 true,则 selectedIndex 属性始终设置为介于 0 和 (dataProvider.length - 1) 之间的值。

于 2014-03-19T21:13:10.453 回答