Asp.net - Add blank item at top of dropdownlist

Question

Why is the dropdown not showing my blank item first? Here is what I have

drpList.Items.Add(New ListItem("", ""))

With drpList
    .DataSource = myController.GetList(userid)
    .DataTextField = "Name"
    .DataValueField = "ID"
    .DataBind()
End With

Edit ~ I am binding to a Generig List, could this be the culprit?

Reconcilable

This relates to: #984216 – Steatopygia

Answer 1

After your databind:

drpList.Items.Insert(0, new ListItem(String.Empty, String.Empty));
drpList.SelectedIndex = 0;

Doubledecker

Alternately, you can instantiate a ListItem, set its Selected property to true, and then insert it into drpList as above. – Vick

This may help those looking for an answer to work with sqlDataSource data In my case, I also had to add drpList.AppendDataBoundItems = true; to bind it to the current data in the Page_Load method – Surely

Answer 2

You can use AppendDataBoundItems=true to easily add:

<asp:DropDownList ID="drpList" AppendDataBoundItems="true" runat="server">
    <asp:ListItem Text="" Value="" />
</asp:DropDownList>

Lynseylynus

VS doesn't like the <br /> tag and it works for me without it. This is such a clean option, I don't know why it doesn't have more votes. – Sallyanne

Worked like a charm. Thanks for the design time solution. – Stegodon

Don't forget to set Selected="true" – Sirmons

Answer 3

The databinding takes place after you've added your blank list item, and it replaces what's there already, you need to add the blank item to the beginning of the List from your controller, or add it after databinding.

EDIT:

After googling this quickly as of ASP.Net 2.0 there's an "AppendDataBoundItems" true property that you can set to...append the databound items.

for details see

http://imar.spaanjaars.com/QuickDocId.aspx?quickdoc=281 or

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.listcontrol.appenddatabounditems.aspx

Chouinard

One think you need to watch out for is having your dropdown list grow after each postback by appending the same data over and over. – Weisburgh

Is the blank item not there, or there but just not selected? – Chouinard

This would work if you had the blank one in your .aspx markup, then bound in code behind. – Neumark

Answer 4

I think a better way is to insert the blank item first, then bind the data just as you have been doing. However you need to set the AppendDataBoundItems property of the list control.

We use the following method to bind any data source to any list control...

public static void BindList(ListControl list, IEnumerable datasource, string valueName, string textName)
{
    list.Items.Clear();
    list.Items.Add("", "");
    list.AppendDataBoundItems = true;
    list.DataValueField = valueName;
    list.DataTextField = textName;
    list.DataSource = datasource;
    list.DataBind();
}

Briannabrianne

Answer 5

Like "Whisk" Said, the trick is in "AppendDataBoundItems" property

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        DropDownList1.AppendDataBoundItems = true;
        DropDownList1.Items.Insert(0, new ListItem(String.Empty, String.Empty));
        DropDownList1.SelectedIndex = 0;
    }
}

Thanks "Whisk"

Knuckle

Answer 6

Do your databinding and then add the following:

Dim liFirst As New ListItem("", "")
drpList.Items.Insert(0, liFirst)

Construct

Answer 7

it looks like you are adding a blank item, and then databinding, which would empty the list; try inserting the blank item after databinding

Staton

when I do that, the blank row appears at the bottom. – Reconcilable

You can specify the index to insert into. Look at JasonS' solution. – Ube

@[Saif Khan]: and if that doesn't work, insert the blank row into your datasource, then databind – Staton

Answer 8

simple

at last

ddlProducer.Items.Insert(0, "");

Sepulchre

Answer 9

ddlCategory.DataSource = ds;
ddlCategory.DataTextField = "CatName";
ddlCategory.DataValueField = "CatID";

Cách 1:

ddlCategory.Items.Add(new ListItem("--please select--", "-1"));
ddlCategory.AppendDataBoundItems = true;
ddlCategory.SelectedIndex = -1;

ddlCategory.DataBind();

Cách 2:

ddlCategory.Items.Insert(0, new ListItem("-- please select --", "0"));

(Tested OK)

Chuckchuckfull

Answer 10

You could also have a union of the blank select with the select that has content:

select '' value, '' name
union
select value, name from mytable

Quadrisect

Looking back, I wouldn't recommend this method except only as an alternative. I like the event for flexibility sake (OnDataBound="mydropdown_DataBound"), but in my current case, I'm adopting the (AppendDataBoundItems="true") for simplicity sake. – Quadrisect