我如何为下拉列表框添加“请选择...”选项

Question

I have this code I have to add 'please select..' in the dropdown list box.

<%=Html.DropDownList("defaultSelection", new SelectList(Model.VariableDefaultSelections.ToList(), "ba_Object_id", "ba_Object_id", ViewData["DefaultSelectId"]))%>

Can any body help me out .

Thanks

Answer 1

There's an overload of the DropDownList helper which allows you to achieve that:

<%= Html.DropDownList(
    "defaultSelection", 
    new SelectList(
        Model.VariableDefaultSelections.ToList(), 
        "ba_Object_id", 
        "ba_Object_id", 
        ViewData["DefaultSelectId"]
    ),
    "-- Please Select --"
) %>

Answer 2

You will have to add it in your SelectList, maybe with an Id of -1? The only way I know of is to add it as an option. If you are using HTML5, then I think you might be able to add a meta tag, but that might just be for input types. I will double check...

UPDATE It looks like there is nothing like placeholder (HTML5 input option) for select. However, it looks like the best you have has already been answered here: How do I make a placeholder for a 'select' box?

Answer 3

您始终可以在列表中添加带有禁用选项的选项，这样，一旦单击下拉列表，用户就无法选择它。