In asp.net mvc you can use:
@Html.DropDownListFor(model => model.Category, ViewBag.Category as IEnumerable<SelectListItem>, "-- SELECT --", new { @class = "form-control" })
Using asp.net 5, how do I include the default or null value (-- SELECT --) in a taghelper:
<select asp-for="Category" asp-items="@ViewBag.Category" class="form-control"></select>
You can just insert an option item inside the select:
<select asp-for="Category" asp-items="@ViewBag.Category" class="form-control">
<option disabled selected>--- SELECT ---</option>
</select>
The disabled
keyword in the code above means that the "--- SELECT ---" row cannot be picked again once a choice has been selected in the list. If you want the user to be able to blank the selection again (ie if it's bound to a nullable field) then just omit disabled.
如果要将值 null 存储到数据库,请使用<option selected value="">Full Access</option>
If you use asp-items for your model , It uses value 0 for selected item , If you have tag <option>
with your default string without value ,
You must use a loop for <option>
and put your default option out of loop. This is an example for .Net Core using asp-items:
<select asp-for="DepartmentUnit" asp-items="@Model.DepartmentUnits" class="form-control"></select>
and Now this is another example for using loop:
<select>
<option val="">--Select--</option>
foreach(item in Model.DepartmentUnits)
{<option val="@item.val">@item.title</option>}
</select>
This answer by Matt:
<select asp-for="Category" asp-items="@ViewBag.Category" class="form-control">
<option disabled selected>--- SELECT ---</option>
</select>
also works with validation. Probably due to the option being disabled
it seems not to be a valid selection.
btw.: this also works with MVC Core 3 ;-)
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