take out foreach using linq

Question

Is there a way to take out the foreach in the following code in linq yet produce the same output?

    DropDownList ddl = new DropDownList();
    foreach (DataRow row in ds.Tables[0].Rows)
    {
        if ((byte)row["ListTypeID"] == 0)
        {
            item = new ListItem(row["ListText"].ToString(), string.Format("{0}:{1}", row["ListTypeID"].ToString(), row["ListID"].ToString()));
            ddl.Items.Add(item);
        }
        else
        {
            item = new ListItem(row["ListText"].ToString(), string.Format("{0}", row["ListID"].ToString()));
            ddl.Items.Add(item);
        }
    }

Answer 1

ddl.Items.AddRange(ds.Tables[0].Rows.Select( row => 
(byte)row["ListTypeID"] == 0
  ? new ListItem(row["ListText"].ToString(), string.Format("{0}:{1}", row["ListTypeID"].ToString(), row["ListID"].ToString()))
  : new ListItem(row["ListText"].ToString(), string.Format("{0}", row["ListID"].ToString()))           
));

a bit of cleaning

ddl.Items.AddRange(ds.Tables[0].Rows.Select( row => 
(byte)row["ListTypeID"] == 0
  ? new ListItem(row["ListText"].ToString(), string.Format("{0}:{1}", row["ListTypeID"], row["ListID"]))
  : new ListItem(row["ListText"].ToString(), string.Format("{0}", row["ListID"]))           
));

leave foreach :)

Answer 2

Instead of cramming all into a one-line lambda, I prefer readability over saving line space:

ddl.Items.AddRange(ds.Tables[0].Rows.Select( row => 
    {
        var listText = row["ListText"];
        var listTypeId = (byte)row["ListTypeID"];
        var listId = row["ListID"];

        var format = listTypeId == 0 ? "{0}:{1}" : "{1}";
        var itemText = String.Format(format, listTypeID, listId);

        return new ListItem(listText, itemText);
    }
    ));

Answer 3

You can use something like this

 var Items= (from DataRow dr in ds.Tables[0].AsEnumerable() 
        select new { 
        Text=dr.Field<string>("ListText"), 
        Value =dr.Field<byte>("ListTypeID") == 0?string.Format("{0}:{1}", dr.Field<string>("ListTypeID"), dr.Field<string>("ListID")):string.Format("{0}", dr.Field<string>("ListID"))
    }).ToList();

now you can use Items as data-source for the dropdown.

Answer 4

After a bit of reordering you can achieve the following - adding the items excluded.

var items = ds.Tables[0].Rows.Select(row =>
   new ListItem(row["ListText"].ToString(),
                String.Format(
                   (Byte)row["ListTypeID"] == 0 ? "{0}:{1}" : "{1}",
                   row["ListTypeID"], row["ListID"])));