与数据库绑定后在下拉列表中添加默认值

Question

I binded my ddl to my database as below, but how can I add a default text on top of the binded values so that it appears as:

Select Color ---> default text
Red ---> database value
Blue ---> database value
Green ---> database value   

Code:

    DropDownList ddlSize = (DropDownList)FormView_Product.Row.Cells[0].FindControl("ddlSize");
    CommerceEntities db = new CommerceEntities();

    ddlColor.DataSource = from p in db.ProductTypes
                                      where p.ProductID == pID
                                      orderby p.Color 
                                      select new { p.Color };
    ddlColor.DataTextField = "Color";

Thanks!

Answer 1

After data-binding, do this:

ddlColor.Items.Insert(0, new ListItem("Select","NA")); //updated code

Or follow Brian's second suggestion if you want to do it in markup.

You should probably add a RequiredFieldValidator control and set its InitialValue to "NA".

<asp:RequiredFieldValidator .. ControlToValidate="ddlColor" InitialValue="NA" />

Answer 2

You can do it programmatically:

ddlColor.DataSource = from p in db.ProductTypes
                                  where p.ProductID == pID
                                  orderby p.Color 
                                  select new { p.Color };
ddlColor.DataTextField = "Color";
ddlColor.DataBind();
ddlColor.Items.Insert(0, new ListItem("Select", "NA"));

Or add it in markup as:

<asp:DropDownList .. AppendDataBoundItems="true">
   <Items>
       <asp:ListItem Text="Select" Value="" />
   </Items>
</asp:DropDownList>

Answer 3

You can add it programmatically or in the markup, but if you add it programmatically, rather than Add the item, you should Insert it as position zero so that it is the first item:

ddlColor.DataSource = from p in db.ProductTypes
                      where p.ProductID == pID
                      orderby p.Color
                      select new { p.Color };
ddlColor.DataTextField = "Color";
ddlColor.DataBind();
ddlColor.Items.Insert(0, new ListItem("Select Color", "");

The default item is expected to be the first item in the list. If you just Add it, it will be on the bottom and will not be selected by default.

Answer 4

design

<asp:DropDownList ID="ddlArea" DataSourceID="ldsArea" runat="server" ondatabound="ddlArea_DataBound" />

codebehind

protected void ddlArea_DataBound(object sender, EventArgs e)
{
    ddlArea.Items.Insert(0, new ListItem("--Select--", "0"));
}

Answer 5

The solution provided by Justin should work. To be sure making use of SelectedIndex property will also help.

ddlColor.DataSource = from p in db.ProductTypes
                      where p.ProductID == pID
                      orderby p.Color
                      select new { p.Color };

ddlColor.DataTextField = "Color";
ddlColor.DataBind();

ddlColor.Items.Insert(0, new ListItem("Select Color", ""); 
ddlColor.SelectedIndex = 0;