How to SELECT a dropdown list item by value progra

问题:

How to SELECT a drop down list item by value programatically in C#.NET?

回答1:

If you know that the dropdownlist contains the value you're looking to select, use:

ddl.SelectedValue = "2";

If you're not sure if the value exists, use (or you'll get a null reference exception):

ListItem selectedListItem = ddl.Items.FindByValue("2");

if (selectedListItem != null)
{
    selectedListItem.Selected = true;
}

回答2:

myDropDown.SelectedIndex = 
    myDropDown.Items.IndexOf(myDropDown.Items.FindByValue("myValue"))

回答3:

ddl.SetSelectedValue("2");

With a handy extension:

public static class WebExtensions
{

    /// <summary>
    /// Selects the item in the list control that contains the specified value, if it exists.
    /// </summary>
    /// <param name="dropDownList"></param>
    /// <param name="selectedValue">The value of the item in the list control to select</param>
    /// <returns>Returns true if the value exists in the list control, false otherwise</returns>
    public static Boolean SetSelectedValue(this DropDownList dropDownList, String selectedValue)
    {
        ListItem selectedListItem = dropDownList.Items.FindByValue(selectedValue);

        if (selectedListItem != null)
        {
            selectedListItem.Selected = true;
            return true;
        }
        else
            return false;
    }
}

Note: Any code is released into the public domain. No attribution required.

回答4:

combobox1.SelectedValue = x;

I suspect you may want yo hear something else, but this is what you asked for.

回答5:

This is a simple way to select an option from a dropdownlist based on a string val

private void SetDDLs(DropDownList d,string val)
    {
        ListItem li;
        for (int i = 0; i < d.Items.Count; i++)
        {
            li = d.Items[i];
            if (li.Value == val)
            {
                d.SelectedIndex = i;
                break;
            }
        }
    }

回答6:

Ian Boyd (above) had a great answer -- Add this to Ian Boyd's class "WebExtensions" to select an item in a dropdownlist based on text:

    /// <summary>
    /// Selects the item in the list control that contains the specified text, if it exists.
    /// </summary>
    /// <param name="dropDownList"></param>
    /// <param name="selectedText">The text of the item in the list control to select</param>
    /// <returns>Returns true if the value exists in the list control, false otherwise</returns>
    public static Boolean SetSelectedText(this DropDownList dropDownList, String selectedText)
    {
        ListItem selectedListItem = dropDownList.Items.FindByText(selectedText);

        if (selectedListItem != null)
        {
            selectedListItem.Selected = true;
            return true;
        }
        else
            return false;
    }

To call it:

WebExtensions.SetSelectedText(MyDropDownList, "MyValue");

回答7:

For those who come here by search (because this thread is over 3 years old):

string entry // replace with search value

if (comboBox.Items.Contains(entry))
   comboBox.SelectedIndex = comboBox.Items.IndexOf(entry);
else
   comboBox.SelectedIndex = 0;

回答8:

Take a look at this article

How to select an item in a DropDownList by value Asp.Net

回答9:

I prefer

if(ddl.Items.FindByValue(string) != null)
{
    ddl.Items.FindByValue(string).Selected = true;
}

Replace ddl with the dropdownlist ID and string with your string variable name or value.

回答10:

ddlPageSize.Items.FindByValue("25").Selected = true;