从Codebehind下拉列表项 [英] Drop Down List Items from Codebehind

问题描述

你好

我试图根据FormView的值在页面后面的代码中构造一个下拉列表.

我已经对大多数逻辑进行了排序(我认为)以放入正确的值，但是当我从下拉列表中选择一个项目时，原始下拉列表会再次附加相同的值，因此列表会不断增长，那么我要做的就是保留所选项目和原始列表内容(无论页面从下拉列表中被发布回多少次).

我将以下代码放置在Page_Load事件部分中，这可能会导致问题吗?

任何帮助表示赞赏，但请注意，我是这个领域的新手...

Hello

I''m trying to construct a dropdown list in a code behind page, based on the values of a FormView.

I have most of the logic sorted (I think) to put in the correct values, but when I select an item from the drop down list, the orginial drop down list is appended with the same values again, so the list keeps growing and growing, when all I want it to do is retain the selected item and the original list content (no matter how many times the page is posted back from the drop down).

I have placed the following code in the Page_Load event section, could this be causing the problem?

Any help appreciated, but beaware, I''m a newbie in this.....

DropDownList3.Items.Add("-");
if (callDetails.DataKey["SOURCE_REFERENCE"] != "")
{
    DropDownList3.Items.Add("Source");
}
if (callDetails.DataKey["SUBJECT_REFERENCE"] != "")
{
    DropDownList3.Items.Add("Subject");
}
if (callDetails.DataKey["REFERENCE"] != "")
{
    DropDownList3.Items.Add("3rd Party");
}

推荐答案

将您的代码放入

Put your code like

if(!IsPostBack)
{
DropDownList3.Items.Add("-");
if (callDetails.DataKey["SOURCE_REFERENCE"] != "")
{   
 DropDownList3.Items.Add("Source");
}
if (callDetails.DataKey["SUBJECT_REFERENCE"] != "")
{   
 DropDownList3.Items.Add("Subject");
}
if (callDetails.DataKey["REFERENCE"] != "")
{   
 DropDownList3.Items.Add("3rd Party");}
}
}

现在，您的代码将不会执行一次以上.

Now your code will not be executed more than once.

布里吉

如果是回发，我会结合使用您的代码和一些要处理的东西.

似乎可以完成工作，但是可能会有一种更流畅的方式.

还是谢谢你.

干杯

彼得

Hi Brij

I used a combination of your code and something to handle if it is a postback.

Seems to do the job but there might be a slicker way.

Thanks anyway.

Cheers

Peter

if (!IsPostBack)
{
    DropDownList3.Items.Add(new ListItem("-", "-"));
    if (callDetails.DataKey["SOURCE_REFERENCE"] != "")
    {
        DropDownList3.Items.Add(new ListItem("Source", callDetails.DataKey["SOURCE_REFERENCE"].ToString()));
        Label10.Text = DropDownList3.SelectedValue.ToString();
    }
    if (callDetails.DataKey["SUBJECT_REFERENCE"] != "")
    {
        DropDownList3.Items.Add(new ListItem("Subject", callDetails.DataKey["SUBJECT_REFERENCE"].ToString()));
        Label10.Text = DropDownList3.SelectedValue.ToString();
    }
    if (callDetails.DataKey["REFERENCE"] != "")
    {
        DropDownList3.Items.Add(new ListItem("3rd Party", callDetails.DataKey["REFERENCE"].ToString()));
        Label10.Text = DropDownList3.SelectedValue.ToString();
    }
}

if (IsPostBack)
{
    if (callDetails.DataKey["SOURCE_REFERENCE"] != "")
    {
        Label10.Text = DropDownList3.SelectedValue.ToString();
    }
    if (callDetails.DataKey["SUBJECT_REFERENCE"] != "")
    {
        Label10.Text = DropDownList3.SelectedValue.ToString();
    }
    if (callDetails.DataKey["REFERENCE"] != "")
    {
        Label10.Text = DropDownList3.SelectedValue.ToString();
    }
}

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