C# – inserting items to dropdownlist

asp.netcdata-binding

I want to display the items in my dropdownlist2 (from table 2 )based on the selected item of the dropdownlist1(from table 1) .

in the following, i just tried to select the lang column values from table2 based on the value which is in the dropdownlist1..((just to insert into the dropdownlist1))
is that correct code…?

    SqlDataAdapter da = new SqlDataAdapter(
       "Select lang from table2 whereheatre=@d",connect.con());
    da.SelectCommand.Parameters.AddWithValue("@d", DropDownList1.SelectedItem.Text);
    DataSet ds=new DataSet();
    da.Fill(ds,"l1");
    DropDownList2.Items.Add(ds);

is there any other way to do that…?

Best Answer

To add the new values into an existing dropdownlist, you should add the new rows manualy :

foreach (DataRow dr in ds.Tables[0].Rows)
{
    DropDownList2.Items.Add(new ListItem(dr["TextField"].ToString(), dr["ValueField"].ToString()));
}

Or, you should merge datatables before binding them to your dropdownlist.

For MVC v5.1 use Html.EnumDropDownListFor

@Html.EnumDropDownListFor(
    x => x.YourEnumField,
    "Select My Type", 
    new { @class = "form-control" })

For MVC v5 use EnumHelper

@Html.DropDownList("MyType", 
   EnumHelper.GetSelectList(typeof(MyType)) , 
   "Select My Type", 
   new { @class = "form-control" })

For MVC 5 and lower

I rolled Rune's answer into an extension method:

namespace MyApp.Common
{
    public static class MyExtensions{
        public static SelectList ToSelectList<TEnum>(this TEnum enumObj)
            where TEnum : struct, IComparable, IFormattable, IConvertible
        {
            var values = from TEnum e in Enum.GetValues(typeof(TEnum))
                select new { Id = e, Name = e.ToString() };
            return new SelectList(values, "Id", "Name", enumObj);
        }
    }
}

This allows you to write:

ViewData["taskStatus"] = task.Status.ToSelectList();

by using MyApp.Common

C# – Display the items in DropDownList

Use the SelectedIndexChanged-event on the first dropdownlist. Everytime the user selects a different item in the dropdownlist, this event is fired. In the method body you can now react to the change and filter the items of the second dropdownlist to match the selected item of the first dropdownlist. You can either do that manually in a loop or use LINQ (Enumerable.Select).

Best Answer

Related Solutions

C# – How to create a dropdownlist from an enum in ASP.NET MVC

For MVC v5.1 use Html.EnumDropDownListFor

For MVC v5 use EnumHelper

For MVC 5 and lower

C# – Display the items in DropDownList

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