如何使用c#在asp.net中设置下拉列表值

i have a method to populate the dropdownlist in asp.net using C#

我有一个用c#填充asp.net下拉列表的方法

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

但是值在not set中，因为patteren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

如果我可以在mystore下拉列表中设置UK，任何帮助或指导。国家值是6

2 个解决方案

#1

First of all you don't need to pass ComboBox by reference.

首先，不需要通过引用传递ComboBox。

To select value of DataBoud ComboBox do this:

要选择DataBoud ComboBox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.

它会预先选择赋予价值。

#2

I assume the problem is in this line:

我认为问题在这条线上:

countary_box.Text = countary_box.Items.FindByValue(my_store.countary).ToString();

In ASP.NET you can set the SelectedValue property via the Text property of a DropDownList (like in Winforms). Note the difference, you set the value by the text property. But ListItem.ToString returns the text not the value property.

在ASP。NET可以通过DropDownList的文本属性(如Winforms)设置SelectedValue属性。注意区别，您通过文本属性设置值。但列。ToString返回的是文本而不是值属性。

So you need this:

所以你需要:

countary_box.Text = my_store.countary.ToString(); // if countary is the int which is used as key

or the same using SelectedValue directly:

或直接使用SelectedValue:

countary_box.SelectedValue = my_store.countary.ToString();

#1