如何在 ASP.NET 的 DropDownList 中设置选定的等于 True

Question

I have this code:

@Html.DropDownList("ddlTiposUsuarios", Model.tiposUsuarios.Select(item => new SelectListItem
                               {
                                   Value = item.Id_Tipo_Usuario.ToString(),
                                   Text = item.Nombre_Tipo_Usuario.ToString(),
                                   Selected = "select" == item.Id_Tipo_Usuario.ToString()
                               }), new { @class = "form-select", aria_label = "Default select eaxmple" })

I retrieve a list of four elements from SQL Server and I want to set an option html element which "selected" attribute equals true, depending query from Controller. Any tips?

Answer 1

Instead of creating the SelectList on your View , create the list in your Controller and set it to a ViewBag and see how easy it becomes after that:

In your Controller , do this:

ViewBag.myddlItems = tiposUsuarios.Select(item => new SelectListItem
                               {
                                   Value = item.Id_Tipo_Usuario.ToString(),
                                   Text = item.Nombre_Tipo_Usuario.ToString()
                               });

and then in your View, you can construct your DropDownList using the ViewBag :

<select id="ddlTiposUsuarios" class="form-select" aria_label = "Default select eaxmple">
    @foreach (SelectListItem option in ViewBag.myddlItems)
    {
        <option value="@option.Value" @(option.Value == "select" ? "selected='selected'" : "")>@option.Text</option>
    }
</select>