Sorting a DropDownList? - C#, ASP.NET

If you get a DataTable with the data, you can create a DataView off of this and then bind the drop down list to that. Your code would look something like...

DataView dvOptions = new DataView(DataTableWithOptions);
dvOptions.Sort = "Description";

ddlOptions.DataSource = dvOptions;
ddlOptions.DataTextField = "Description";
ddlOptions.DataValueField = "Id";
ddlOptions.DataBind();

Your text field and value field options are mapped to the appropriate columnns in the data table you are receiving.

It is recommended to sort the data before databinding it to the DropDownList but in case you can not, this is how you would sort the items in the DropDownList.

First you need a comparison class

Public Class ListItemComparer
Implements IComparer(Of ListItem)

Public Function Compare(ByVal x As ListItem, ByVal y As ListItem) As Integer _
Implements IComparer(Of ListItem).Compare

Dim c As New CaseInsensitiveComparer
Return c.Compare(x.Text, y.Text)
End Function
End Class
Then you need a method that will use this Comparer to sort the DropDownList

Public Shared Sub SortDropDown(ByVal cbo As DropDownList)
Dim lstListItems As New List(Of ListItem)
For Each li As ListItem In cbo.Items
lstListItems.Add(li)
Next
lstListItems.Sort(New ListItemComparer)
cbo.Items.Clear()
cbo.Items.AddRange(lstListItems.ToArray)
End Sub
Finally, call this function with your DropDownList (after it's been databound)

SortDropDown(cboMyDropDown)

P.S. Sorry but my choice of language is VB. You can use

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to convert the code from VB to C#

List<ListItem> li = new List<ListItem>();
foreach (ListItem list in DropDownList1.Items)
{
li.Add(list);
}
li.Sort((x, y) => string.Compare(x.Text, y.Text));
DropDownList1.Items.Clear();
DropDownList1.DataSource = li;
DropDownList1.DataTextField = "Text";
DropDownList1.DataValueField = "Value";
DropDownList1.DataBind();

A C# solution for .NET 3.5 (needs System.Linq and System.Web.UI):

public static void ReorderAlphabetized(this DropDownList ddl)
{
List<ListItem> listCopy = new List<ListItem>();
foreach (ListItem item in ddl.Items)
listCopy.Add(item);
ddl.Items.Clear();
foreach (ListItem item in listCopy.OrderBy(item => item.Text))
ddl.Items.Add(item);
}

Call it after you've bound your dropdownlist, e.g. OnPreRender:

protected override void OnPreRender(EventArgs e)
{
base.OnPreRender(e);
ddlMyDropDown.ReorderAlphabetized();
}

Stick it in your utility library for easy re-use.

To sort an object datasource that returns a dataset you use the **Sort** property of the control.

Example usage In the aspx page to sort by ascending order of ColumnName

<asp:ObjectDataSource ID="dsData" runat="server" TableName="Data"
Sort="ColumnName ASC" />

Another option is to put the ListItems into an array and sort.

int i = 0;
string[] array = new string[items.Count];

foreach (ListItem li in dropdownlist.items)
{
array[i] = li.ToString();
i++;

}

Array.Sort(array);

dropdownlist.DataSource = array;
dropdownlist.DataBind();

var list = ddl.Items.Cast<ListItem>().OrderBy(x => x.Text).ToList();

ddl.DataSource = list;
ddl.DataTextField = "Text";
ddl.DataValueField = "Value";
ddl.DataBind();

is better if you sort the Source before Binding it to DropDwonList.
but sort DropDownList.Items like this:

Dim Lista_Items = New List(Of ListItem)

For Each item As ListItem In ddl.Items
Lista_Items.Add(item)
Next

Lista_Items.Sort(Function(x, y) String.Compare(x.Text, y.Text))

ddl.Items.Clear()
ddl.Items.AddRange(Lista_Items.ToArray())
(this case i sort by a string(the item's text), it could be the suplier's name, supplier's id)

the `Sort()` method is for every `List(of )` / `List<MyType>`, you can use it.

You can do it this way is simple

private void SortDDL(ref DropDownList objDDL)
{
ArrayList textList = new ArrayList();
ArrayList valueList = new ArrayList();
foreach (ListItem li in objDDL.Items)
{
textList.Add(li.Text);
}
textList.Sort();
foreach (object item in textList)
{
string value = objDDL.Items.FindByText(item.ToString()).Value;
valueList.Add(value);
}
objDDL.Items.Clear();
for(int i = 0; i < textList.Count; i++)
{
ListItem objItem = new ListItem(textList[i].ToString(), valueList[i].ToString());
objDDL.Items.Add(objItem);
}
}

And call the method this SortDDL(ref yourDropDownList);
and that's it. The data in your dropdownlist will be sorted.

see

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#

You can use this JavaScript function:

function sortlist(mylist)
{
var lb = document.getElementById(mylist);
arrTexts = new Array();
arrValues = new Array();
arrOldTexts = new Array();

for(i=0; i<lb.length; i++)
{
arrTexts[i] = lb.options[i].text;
arrValues[i] = lb.options[i].value;

arrOldTexts[i] = lb.options[i].text;
}

arrTexts.sort();

for(i=0; i<lb.length; i++)
{
lb.options[i].text = arrTexts[i];
for(j=0; j<lb.length; j++)
{
if (arrTexts[i] == arrOldTexts[j])
{
lb.options[i].value = arrValues[j];
j = lb.length;
}
}
}
}