限制用户一次选择给定的下拉列表值 [英] Restricting the user to select a given dropdownlist value once

问题描述

你好，

我需要将列表中的某些项目绑定到下拉列表中.

完成此操作后，现在我想显示一个文本框，用户可以在该文本框中输入他从下拉列表中选择的值所对应的评论.

现在，在用户选择了特定的下拉列表值之后，我希望该值
不可编辑，因此用户不能在下拉列表中多次选择给定值.

如何限制用户一次选择给定的下拉列表值?

Hello,

I have a requirement in which I am binding some items from a list to a dropdownlist.

After I have accomplished this ,now I want to Display a textbox where a user can enter his comments as per the value selected by him from the dropdownlist.

Now after the user has selected the particular dropdownlist value I want that value to
be non editable so that the user cannot select a given value more than once in a dropdownlist.

How to restrict the user to select a given dropdownlist value once?

ddldropPPO.Items.Add(testdef.PPO1.ToString());  //Items fetched from a list
string PPO = ddldropPPO.SelectedItem.Text;
TextBox txtreason = new TextBox();
string reason = txtreason.Text;

推荐答案

最简单的方法是从集合中删除该值，并在用户选择该值后重新绑定.

The simplest way would be to remove the value from the collection and rebind after the user has selected that value.

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