将值添加到下拉列表 [英] Adding values to dropdownlist

问题描述

大家好，
正在将excelsheet名称添加到dropdownlist
问题是，如果现有文件被上传以覆盖，则将dropdownlist值添加两次，我如何验证同名项目只能添加一次

Hi all,
am adding the excelsheet names to dropdownlist
problem is if the existing file is uploaded for overwrite then the dropdownlist values are added twice ,how can i validate that the item with same name must be added only once

推荐答案

作为一个简单的解决方案，编写您自己的方法以消除重复项，如下所示:

As a simple solution, write your own method to eliminate the duplicate entry as:

public static void RemoveDuplicateItems(DropDownList ddl)
    {
        for (int i = 0; i < ddl.Items.Count; i++)
        {
            ddl.SelectedIndex = i;
            string currValue = ddl.SelectedItem.ToString();
            for (int counter = i + 1; counter < ddl.Items.Count; counter++)
            {
                ddl.SelectedIndex = counter;
                if (currValue == ddl.SelectedItem.ToString())
                {
                    ddl.Items.RemoveAt(counter);
                    counter = counter - 1;
                }
            }
        }

在将项目添加到下拉列表之前，请使用Contains属性检查现有项目

Before Adding Items to DropDown Lists check Existing Item using Contains Property

<pre lang="cs">DropDownList ddl= new DropDownList();


      if(!ddl.Items.Contains(new ListItem("item")))
      {
          ddl.Items.Add(new ListItem("item"));


      }

如果要调用DataBind()方法，请确保列表为先清除"

If you are calling DataBind() method make sure the List is Clear First

if(ddl.Items.Count>0)
ddl.Items.Clear();

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