在DropDownList中选择值

本文介绍了在DropDownList中选择值的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我有一个名为master_litigants的主表
我将这些数据填充到一个下拉列表中
表格如下:-
Litigant_id Litigant_type Litignat_value
1 PETITIONER P
2响应R
3第三方T

ddlLitigantType.DataTextField ="Litigants_Type";
ddlLitigantType.DataValueField ="Litigants_value";
ddlLitigantType.DataBind();
我已将is(P，R，T)的值插入其他表中

为了更新，我从其他位置读取了数据，并希望显示在下拉列表中
为此，我正在使用代码
1)ddlLitigantType.SelectedValue = dr ["Litigant_type"].ToString();
和
2)ddlLitigantType.Items.FindByValue(dr ["Litigant_type"].ToString()).Selected = true;
两个代码都显示错误:

1)第一个代码的错误是:-ddlLitigantType的SelectedValue无效，因为它不存在于项目列表中.参数名称:值(但是ddlLitigant仅在页面加载中加载，因此存在该值)
2)第一个代码的错误是:-对象引用未设置为对象的实例.

我做错了吗r还有其他方法吗?
请帮助我

I have a master table called master_litigants
i m populating this data into a dropdown list
the table as follows:-
Litigant_id Litigant_type Litignat_value
1 PETITIONER P
2 RESPONDENTR
3 THIRD PARTYT

ddlLitigantType.DataTextField = "Litigants_Type";
ddlLitigantType.DataValueField = "Litigants_value";
ddlLitigantType.DataBind();
I have inserted Value that is(P,R,T) into other table

for updation i read the data from other and want to show in the dropdown list
for that i m using code
1)ddlLitigantType.SelectedValue = dr["Litigant_type"].ToString();
and
2)ddlLitigantType.Items.FindByValue(dr["Litigant_type"].ToString()).Selected = true;
both code showing Error:

Error for 1)st code is:-ddlLitigantType has a SelectedValue which is invalid because it does not exist in the list of items. Parameter name: value(But the ddlLitigant is loaded in the page load only so the value is present)
Error for 2)nd code is:-Object reference not set to an instance of an object.

m i doing it wrong r is there any other way of doing it.
plZ help me

ddlLitigantType

在DropDownList中选择值

问题描述

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