如何使用 C# 在 asp.net 中设置 Dropdownlist 值
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How to set Dropdownlist value in asp.net using C#
提问by syed Ahsan Jaffri
i have a method to populate the dropdownlist in asp.net using C#
我有一种方法可以使用 C# 在 asp.net 中填充下拉列表
public void get_country_box_populated(ref System.Web.UI.WebControls.DropDownList dropDown, bool add_initial_text)
{
dropDown.Items.Clear();
//dropDown.Items.Add(0,"Select Any Country");
var context = new db_vmartEntities();
var query = from c in context.tbl_countary
where c.status == true
select new { c.countary_id, c.countary_name };
var dictionary = new Dictionary<int, string>();
if (add_initial_text)
{
dictionary.Add(0, "Select Any Country");
}
foreach (var item in query)
{
dictionary.Add(item.countary_id, item.countary_name);
}
dropDown.DataTextField = "Value";
dropDown.DataValueField = "Key";
dropDown.DataSource = dictionary; //Dictionary<int, string>
dropDown.DataBind();
}
now i need to select a default value on edit page something like this.
现在我需要在像这样的编辑页面上选择一个默认值。
store_registration my_store = str.get_store_by_id(Session["user"].ToString(), sid);
c.get_country_box_populated(ref countary_box,false);
countary_box.Text = countary_box.Items.FindByValue(my_store.countary).ToString();
but value in not set because patteren is like this
但未设置值，因为模式是这样的
Dictionary<key,value>
Dictionary<5,Pakistan>
Dictionary<8,India>
Dictionary<9,Iran>
Dictionary<6,UK>
any help or guide if i can set UK in dropdownlist when mystore.country value is 6
当 mystore.country 值为 6 时，如果我可以在下拉列表中设置 UK 有任何帮助或指南
回答by gzaxx
First of all you don't need to pass ComboBoxby reference.
首先，您不需要ComboBox通过引用传递。
To select value of DataBoudComboBox do this:
要选择DataBoudComboBox 的值，请执行以下操作：
countary_box.SelectedValue = my_store.countary_id; //im not 100% sure that this is the key, so change it to equivalent of item.countary_id
And it will preselect give value.
它会预先选择给值。
回答by Tim Schmelter
I assume the problem is in this line:
我认为问题出在这一行：
countary_box.Text = countary_box.Items.FindByValue(my_store.countary).ToString();
In ASP.NET you can set the SelectedValueproperty via the Textpropertyof a DropDownList(like in Winforms). Note the difference, you set the value by the text property. But ListItem.ToStringreturns the text not the value property.
在ASP.NET中，您可以设置SelectedValue通过属性Text特性的DropDownList（如在的WinForms）。注意区别，您通过 text 属性设置值。但ListItem.ToString返回文本而不是 value 属性。
So you need this:
所以你需要这个：
countary_box.Text = my_store.countary.ToString(); // if countary is the int which is used as key
or the same using SelectedValuedirectly:
或同样SelectedValue直接使用：
countary_box.SelectedValue = my_store.countary.ToString();
