更改嵌套的中继器内DropDownList的选定值

问题描述

我试图DropDownList中选定值从C＃​​code改变：

 ＆LT;转发器GT;
   ＆LT;转发器GT;
      ＆LT;＆下拉GT;
 

和我在aspx页面的数据源添加到下拉列表
每一件事工作正常..但我想改变的下拉列表中选择的值的onload
要能显示用户的previous选择的名称时，编辑表格

 保护无效prepairDropDownList（对象发件人，EventArgs的发送）
    {
        shiftrepeater.DataBind（）;
        如果（shiftrepeater.Items.Count大于0）
        {
            对于（INT shiftCount转换= 0;＆shiftCount转换LT; shiftrepeater.Items.Count; shiftCount转换++）
            {
                直放站TEMP =（中继器）shiftrepeater.Items [shiftCount转换] .FindControl（saturdayrepeater）;
                如果（temp.Items.Count大于0）
                {
                    对于（诠释计数= 0; COUNT＆LT; temp.Items.Count;计数++）
                    {
                        DropDownList的DS =（DropDownList的）temp.Items [统计] .FindControl（userdropdown）;
                        HiddenField HF =（HiddenField）temp.Items [统计] .FindControl（hiddenid）; //包含ID如果该字段
                        SarcShiftUser用户= CRUD＆LT; SarcShiftUser＆GT;获得（int.Parse（hf.Value））; //一个方法来选择与特定ID的用户，并将其添加从类sarcshiftuser对象                        如果（user.id == 0）
                            ds.SelectedValue =;
                        其他
                        {
                            ds.SelectedValue = user.user_id +;                        }
                    }
                }            }
        }
        shiftrepeater.DataBind（）;
    }
 

我这个方法添加到中继器的Onload：
但没有任何变化和previous的名字并未出现。

P.S：用户对象是正确的并且user.user_id也是正确的
P.S 2：我尝试添加ds.DataBind（）;改变选择，但给该错误后：

  System.ArgumentOutOfRangeException：'userdropdown'具有的SelectedValue，因为它不在项目列表中存在这是无效的。
 

解决方案

设置最安全的方法的SelectedItem A DROPDOWNLIST 是设置的SelectedIndex 是这样的：

  ds.SelectedIndex = ds.Items.IndexOf（ds.Items.FindByValue（user.user_id.ToString（）））;
 

I tried to change a dropdownlist selected value from a c# code :

<repeater >
   <repeater>
      <dropdown>

and I add a datasource in aspx page to the dropdownevery thing works fine .. but I want to change the selected value onload of the dropdownto be able to show the user the previous selected name when edit the table

protected void PrepairDropDownList(object sender,EventArgs e)
    {
        shiftrepeater.DataBind();
        if (shiftrepeater.Items.Count > 0)
        {
            for (int shiftcount = 0; shiftcount < shiftrepeater.Items.Count; shiftcount++)
            {
                Repeater temp = (Repeater)shiftrepeater.Items[shiftcount].FindControl("saturdayrepeater");
                if (temp.Items.Count > 0)
                {
                    for (int count = 0; count < temp.Items.Count; count++)
                    {
                        DropDownList ds = (DropDownList)temp.Items[count].FindControl("userdropdown");
                        HiddenField hf = (HiddenField)temp.Items[count].FindControl("hiddenid");//contain the id if the field
                        SarcShiftUser user = CRUD<SarcShiftUser>.Get(int.Parse(hf.Value)); //a method to select a user with a specific id and add it to object from class sarcshiftuser

                        if (user.id == 0)
                            ds.SelectedValue = "";
                        else
                        {
                            ds.SelectedValue = user.user_id + "";

                        }
                    }
                }

            }
        }
        shiftrepeater.DataBind();
    }

I add this method to Onload of the repeater :but nothing change and the previous name didn't show

P.S : the user object is correct and the user.user_id is also correctP.S 2 : I tried to add a ds.DataBind(); after changing the selected but give that error :

System.ArgumentOutOfRangeException: 'userdropdown' has a SelectedValue which is invalid because it does not exist in the list of items.

解决方案

Safest way to set SelectedItem of a DropdownList is to set the SelectedIndex like this:

ds.SelectedIndex = ds.Items.IndexOf(ds.Items.FindByValue(user.user_id.ToString()));

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