DropdownList.selectedIndex始终为0（是的，我也有！的IsPostBack） [英] DropdownList.selectedIndex always 0 (yes, I do have !isPostBack)

问题描述

（向下滚动后的底部找到解决办法。）

得到其含有一个asp.net页
DataList控件。这里面的DataList，有
由含有模板的
的dropdownlist并且每次
数据列表充满了一个项目，一个
ItemCreatedCommand被调用。该
itemCreatedCommand负责
数据绑定DropDownList的。

我觉得问题就出在这里，那
我使用ItemCreatedCommand到
填充它 - 但奇怪的事情
是，如果我选择的颜色绿色，
页面会自动回，我就
看到的下拉仍然在
色绿，而是试图用时
它的selectedIndex，我总是得到0 ...

 保护无效DataListProducts_ItemCreatedCommand（对象
    源，DataListItemEventArgs E） VAR的itemId =（字符串）DataListProducts.DataKeys [e.Item.ItemIndex]
 VAR项目= itemBLL.GetFullItem（的itemId）; VAR DropDownListColor =（DropDownList的）e.Item.FindControl（DropDownListColor）; //也试过用：
 //如果（！的IsPostBack）{ DropDownListColor.DataSource = item.ColorList;
 DropDownList.Color.Databind（）; //}结束！的IsPostBack）    Label1.test = DropDownListColor.SelectedIndex.toString（）;
 //＆LT;  - 这始终是0！ * GRR *
 

我已经收窄code位为
查看，但你仍然可以看到什么
我试图做:)原因
为什么我这样做，并没有宣布
数据源直接的颜色
我ASPX页面，就是我需要运行
如果测试（showColors），但我不希望
杂波与code中的HTML页
我觉得应该是在code
后面的文件。

编辑：试图改变后
SelectedIndexChange - 我有一个
在我的脑袋逻辑现在的困惑 -
我怎么改变里面的元素
DataList控件？因为，据我知道 - 我
没有任何的方法来检查，其中
在此DataList控件的项目
特别的DropDownList属于...
要么？我要去尝试一些方法
，看看我结束了;）但是做
请发表您对这个想法
问题:)

解决方案：

无论气泡的事件来ItemCommand，或处理的情况下，获得的发送者的父（这是一个的DataListItem并在那里操纵元件

 保护无效DropDownListColor_SelectedIndexChanged（对象发件人，EventArgs的发送）
        {
            DropDownList的dropDownListColor =（DropDownList的）寄件人;
            的DataListItem的DataListItem =（的DataListItem）dropDownListColor.Parent;            VAR项目=项目[dataListItem.ItemIndex]
            VAR颜色= item.ItemColor [dropDownListColor.SelectedIndex]            VAR LabelPrice =（标签）dataListItem.FindControl（LabelPrice）;
            LabelPrice.Text = color.Price;
        }
 

解决方案

在DataList控件是数据绑定，将AutoPostBack尚未处理，即在ItemCreated事件中的值仍然是原来的值。

您需要处理的下拉控制的SelectedIndexChange事件。

(Scroll down to bottom of post to find solution.)

Got a asp.net page which contains a Datalist. Inside this datalist, there is a template containing a dropdownlist and each time the datalist is filled with an item, a ItemCreatedCommand is called. The itemCreatedCommand is responsible for databinding the dropdownlist.

I think the problem lies here, that I'm using ItemCreatedCommand to populate it - but the strange things is that if I choose the color "green", the page will autopostback, and I will see that the dropdown is still on the color green, but when trying to use it's SelectedIndex, I always get 0...

protected void DataListProducts_ItemCreatedCommand(object
    source, DataListItemEventArgs e)

 var itemId = (String)DataListProducts.DataKeys[e.Item.ItemIndex];
 var item = itemBLL.GetFullItem(itemId); 

 var DropDownListColor = (DropDownList)e.Item.FindControl("DropDownListColor");

 //Also tried with :
 //if(!isPostBack) {

 DropDownListColor.DataSource = item.ColorList;
 DropDownList.Color.Databind();

 // } End !isPostBack)

    Label1.test = DropDownListColor.SelectedIndex.toString();
 // <- THIS IS ALWAYS 0! *grr*

I've narrowed down the code a bit for viewing, but still you can see what I'm trying to do :) The reason for why I'm doing this, and not declaring the datasource for the colors directly i aspx-page, is that I need to run a test if(showColors), but I do not want to clutter up the html-page with code that I feel should be in the code behind-file.

EDIT: After trying to alter SelectedIndexChange - I'm having a "logical" confusion in my head now - how am I to alter elements inside the datalist? Since, as far as I know - I do not have any way to check which of the items in the datalist this particular dropdownlist belongs to... Or? I'm going to try out a few ways and see what I end up with ;) But do please post your thoughts on this question :)

SOLUTION:

Either bubble the event to ItemCommand, or Handle the event, get the senders parent(which is a datalistItem and manipulate elements in there.

 protected void DropDownListColor_SelectedIndexChanged(object sender, EventArgs e)
        {
            DropDownList dropDownListColor = (DropDownList)sender;
            DataListItem dataListItem = (DataListItem)dropDownListColor.Parent;

            var item = items[dataListItem.ItemIndex];
            var color = item.ItemColor[dropDownListColor.SelectedIndex];

            var LabelPrice = (Label)dataListItem.FindControl("LabelPrice");
            LabelPrice.Text = color.Price; 
        }

解决方案

When the DataList is data-bound, the AutoPostBack has not been handled yet, i.e. the values in the ItemCreated event are still the original values.

You need to handle the SelectedIndexChange event of the dropdown control.

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