Rellenar una lista desplegable de navajas desde una Lista <objeto> en MVC

Tengo un modelo:

public class DbUserRole
    {
        public int UserRoleId { get; set; }
        public string UserRole { get; set; }
    }

public class DbUserRoles
    {
        public List<DbUserRole> GetRoles()
        {
            BugnetReports RoleDropDown = new BugnetReports();
            List<DbUserRole> Roles = new List<DbUserRole>();
            DataSet table = RoleDropDown.userRoleDropDown();
            foreach (DataRow item in table.Tables[0].Rows)
            {
                DbUserRole ur = new DbUserRole();
                ur.UserRole = Convert.ToString(item["UserRoleName"]);
                ur.UserRoleId = Convert.ToInt32(item["UserRoleID"]);
                Roles.Add(ur);
            }
            return Roles;
        }
    }

Y aquí está el controlador que carga la vista:

        //
        // GET: /Admin/AddNewUser

        public ActionResult AddNewUser()
        {
            DbUserRoles Roles = new DbUserRoles();
            return View(Roles.GetRoles());
        }

Puedo obtener los elementos de la lista para mostrar usando un @foreachbucle como se muestra a continuación:

@foreach (var item in Model)
       {
           <tr>
               <td>
                   @item.UserRoleId
               </td>
               <td>
                   @item.UserRole
               </td>
           </tr>
       }

Pero, ¿cómo rellenar una lista desplegable con el modelo que se pasa, he intentado

@Html.DropDownListFor(x => x.UserRole)

Pero no tengo suerte.

Puede separar su lógica empresarial en un modelo de vista, para que su vista tenga una separación más limpia.

Primero cree un modelo de vista para almacenar el Id que el usuario seleccionará junto con una lista de elementos que aparecerán en el DropDown.

ViewModel:

public class UserRoleViewModel
{
    // Display Attribute will appear in the Html.LabelFor
    [Display(Name = "User Role")]
    public int SelectedUserRoleId { get; set; }
    public IEnumerable<SelectListItem> UserRoles { get; set; }
}

Referencias

• DisplayAttribute

Dentro del controlador, cree un método para obtener su UserRolelista y transformarla en el formulario que se presentará en la vista.

Controlador:

private IEnumerable<SelectListItem> GetRoles()
{
    var dbUserRoles = new DbUserRoles();
    var roles = dbUserRoles
                .GetRoles()
                .Select(x =>
                        new SelectListItem
                            {
                                Value = x.UserRoleId.ToString(),
                                Text = x.UserRole
                            });

    return new SelectList(roles, "Value", "Text");
}

public ActionResult AddNewUser()
{
    var model = new UserRoleViewModel
                    {
                        UserRoles = GetRoles()
                    };
    return View(model);
}

Referencias

• SelectListItem
• SelectList Constructor (IEnumerable, String, String)

Ahora que se creó el modelo de vista, la lógica de presentación se simplificó

Ver:

@model UserRoleViewModel

@Html.LabelFor(m => m.SelectedUserRoleId)
@Html.DropDownListFor(m => m.SelectedUserRoleId, Model.UserRoles)

Referencias

• LabelExtensions.LabelFor
• SelectExtensions.DropDownListFor

Esto producirá:

<label for="SelectedUserRoleId">User Role</label>
<select id="SelectedUserRoleId" name="SelectedUserRoleId">
    <option value="1">First Role</option>
    <option value="2">Second Role</option>
    <option value="3">Etc...</option>
</select>

  @Html.DropDownList("ddl",Model.Select(item => new SelectListItem
{
    Value = item.RecordID.ToString(),
    Text = item.Name.ToString(),
     Selected = "select" == item.RecordID.ToString()
}))

Una forma podría ser;

    <select name="listbox" id="listbox">
    @foreach (var item in Model)
           {

                   <option value="@item.UserRoleId">
                      @item.UserRole 
                   </option>                  
           }
    </select>

Algo cercano a:

@Html.DropDownListFor(m => m.UserRole, 
   new SelectList(Model.Roles, "UserRoleId", "UserRole", Model.Roles.First().UserRoleId), 
   new { /* any html  attributes here */ }) 

Necesita una SelectList para completar DropDownListFor. Para cualquier atributo HTML que necesite, puede agregar:

new { @class = "DropDown", @id = "dropdownUserRole" }

En lugar de a List<UserRole>, puede dejar que su Modelo contenga a SelectList<UserRole>. Agregue también una propiedad SelectedUserRoleIdpara almacenar ... bueno ... el valor de Id de UserRole seleccionado.

Rellene la Lista de selección, luego en su Vista use:

@Html.DropDownListFor(x => x.SelectedUserRoleId, x.UserRole)

y deberías estar bien.

Consulte también http://msdn.microsoft.com/en-us/library/system.web.mvc.selectlist(v=vs.108).aspx .

Su llamado a DropDownListFornecesita algunos parámetros más para desarrollarlo. Necesita una SelectList como en la siguiente pregunta SO:

MVC3 DropDownListFor: ¿un ejemplo simple?

Con lo que tiene allí, solo le ha dicho dónde almacenar los datos, no desde dónde cargar la lista.

   @{
        List<CategoryModel> CategoryList = CategoryModel.GetCategoryList(UserID);
        IEnumerable<SelectListItem> CategorySelectList = CategoryList.Select(x => new SelectListItem() { Text = x.CategoryName.Trim(), Value = x.CategoryID.Trim() });
    }
    <tr>
        <td>
            <B>Assigned Category:</B>
        </td>
        <td>
            @Html.DropDownList("CategoryList", CategorySelectList, "Select a Category (Optional)")
        </td>
    </tr>

Voy a abordar esto como si tuviera un modelo de Usuarios:

Users.cs

public class Users
{
    [Key]
    public int UserId { get; set; }

    [Required]
    public string UserName { get; set; }

    public int RoleId { get; set; }

    [ForeignKey("RoleId")]
    public virtual DbUserRoles DbUserRoles { get; set; }
}

y un modelo DbUserRoles que representaba una tabla con ese nombre en la base de datos:

DbUserRoles.cs

public partial class DbUserRoles
{
    [Key]
    public int UserRoleId { get; set; }

    [Required]
    [StringLength(30)]
    public string UserRole { get; set; }
}

Una vez que haya limpiado eso, debería poder crear y completar una colección de Roles de usuario, como este, en su Controlador:

var userRoleList = GetUserRolesList();
ViewData["userRoles"] = userRolesList;

y tiene estas funciones de soporte:

private static SelectListItem[] _UserRolesList;

/// <summary>
/// Returns a static category list that is cached
/// </summary>
/// <returns></returns>
public SelectListItem[] GetUserRolesList()
{
    if (_UserRolesList == null)
    {
        var userRoles = repository.GetAllUserRoles().Select(a => new SelectListItem()
         {
             Text = a.UserRole,
             Value = a.UserRoleId.ToString()
         }).ToList();
         userRoles.Insert(0, new SelectListItem() { Value = "0", Text = "-- Please select your user role --" });

        _UserRolesList = userRoles.ToArray();
    }

    // Have to create new instances via projection
    // to avoid ModelBinding updates to affect this
    // globally
    return _UserRolesList
        .Select(d => new SelectListItem()
    {
         Value = d.Value,
         Text = d.Text
    })
     .ToArray();
}

Repository.cs

Mi función de repositorio GetAllUserRoles()para la función, arriba:

public class Repository
{
    Model1 db = new Model1(); // Entity Framework context

    // User Roles
    public IList<DbUserRoles> GetAllUserRoles()
    {
        return db.DbUserRoles.OrderBy(e => e.UserRoleId).ToList();
    }
}

AddNewUser.cshtml

Luego haz esto en tu Vista:

<table>
    <tr>
        <td>
            @Html.EditorFor(model => model.UserName,
                  htmlAttributes: new { @class = "form-control" }
                  )
        </td>
        <td>
            @Html.DropDownListFor(model => model.RoleId,
                  new SelectList( (IEnumerable<SelectListItem>)ViewData["userRoles"], "Value", "Text", model.RoleId),
                  htmlAttributes: new { @class = "form-control" }
                  )
         </td>
     </tr>
 </table>

@model AdventureWork.CRUD.WebApp4.Models.EmployeeViewModel
@{
    ViewBag.Title = "Detalle";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

<h2>Ingresar Usuario</h2>

@using (Html.BeginForm())
{

    @Html.AntiForgeryToken()
<div class="form-horizontal">


    <hr />
    @Html.ValidationSummary(true, "", new { @class = "text-danger" })

    <div class="form-group">
        @Html.LabelFor(model => model.Employee.PersonType, labelText: "Tipo de Persona", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.DropDownListFor(model => model.Employee.PersonType, new List<SelectListItem>
       {
               new SelectListItem{ Text= "SC", Value = "SC" },
               new SelectListItem{ Text= "VC", Value = "VC" },
                  new SelectListItem{ Text= "IN", Value = "IN" },
               new SelectListItem{ Text= "EM", Value = "EM" },
                new SelectListItem{ Text= "SP", Value = "SP" },

       }, htmlAttributes: new { @class = "form-control" })
            @Html.ValidationMessageFor(model => model.Employee.PersonType, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.Employee.EmployeeGender, labelText: "Genero", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.DropDownListFor(model => model.Employee.EmployeeGender, new List<SelectListItem>
       {
           new SelectListItem{ Text= "Masculino", Value = "M" },
           new SelectListItem{ Text= "Femenino", Value = "F" }
       }, htmlAttributes: new { @class = "form-control" })
            @Html.ValidationMessageFor(model => model.Employee.EmployeeGender, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.Employee.PersonTitle, labelText: "Titulo", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.Employee.PersonTitle, new { htmlAttributes = new { @class = "form-control" } })
            @Html.ValidationMessageFor(model => model.Employee.PersonTitle, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.Employee.PersonFirstName, labelText: "Primer Nombre", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.Employee.PersonFirstName, new { htmlAttributes = new { @class = "form-control" } })
            @Html.ValidationMessageFor(model => model.Employee.PersonFirstName, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.Employee.PersonMiddleName, labelText: "Segundo Nombre", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.Employee.PersonMiddleName, new { htmlAttributes = new { @class = "form-control" } })
            @Html.ValidationMessageFor(model => model.Employee.PersonMiddleName, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.Employee.PersonLastName, labelText: "Apellido", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.Employee.PersonLastName, new { htmlAttributes = new { @class = "form-control" } })
            @Html.ValidationMessageFor(model => model.Employee.PersonLastName, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.Employee.PersonSuffix, labelText: "Sufijo", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.Employee.PersonSuffix, new { htmlAttributes = new { @class = "form-control" } })
            @Html.ValidationMessageFor(model => model.Employee.PersonSuffix, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.Employee.DepartmentID, labelText: "Departamento", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.DropDownListFor(model => model.Employee.DepartmentID, new SelectList(Model.ListDepartment, "DepartmentID", "DepartmentName"), htmlAttributes: new { @class = "form-control" })
            @Html.ValidationMessageFor(model => model.Employee.DepartmentID, "", new { @class = "text-danger" })
        </div>
    </div>


    <div class="form-group">
        @Html.LabelFor(model => model.Employee.EmployeeMaritalStatus, labelText: "Estado Civil", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.DropDownListFor(model => model.Employee.EmployeeMaritalStatus, new List<SelectListItem>
       {
           new SelectListItem{ Text= "Soltero", Value = "S" },
           new SelectListItem{ Text= "Casado", Value = "M" }
       }, htmlAttributes: new { @class = "form-control" })
            @Html.ValidationMessageFor(model => model.Employee.EmployeeMaritalStatus, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.Employee.ShiftId, labelText: "Turno", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.DropDownListFor(model => model.Employee.ShiftId, new SelectList(Model.ListShift, "ShiftId", "ShiftName"), htmlAttributes: new { @class = "form-control" })
            @Html.ValidationMessageFor(model => model.Employee.ShiftId, "", new { @class = "text-danger" })
        </div>
    </div>



    <div class="form-group">
        @Html.LabelFor(model => model.Employee.EmployeeLoginId, labelText: "Login", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.Employee.EmployeeLoginId, new { htmlAttributes = new { @class = "form-control" } })
            @Html.ValidationMessageFor(model => model.Employee.EmployeeLoginId, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.Employee.EmployeeNationalIDNumber, labelText: "Identificacion Nacional", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.Employee.EmployeeNationalIDNumber, new { htmlAttributes = new { @class = "form-control" } })
            @Html.ValidationMessageFor(model => model.Employee.EmployeeNationalIDNumber, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.Employee.EmployeeJobTitle, labelText: "Cargo", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.Employee.EmployeeJobTitle, new { htmlAttributes = new { @class = "form-control" } })
            @Html.ValidationMessageFor(model => model.Employee.EmployeeJobTitle, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.Employee.EmployeeBirthDate, labelText: "Fecha Nacimiento", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.Employee.EmployeeBirthDate, new { htmlAttributes = new { @class = "form-control datepicker" } })
            @Html.ValidationMessageFor(model => model.Employee.EmployeeBirthDate, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.Employee.EmployeeSalariedFlag, labelText: "Asalariado", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.Employee.EmployeeSalariedFlag, new { htmlAttributes = new { @class = "form-control" } })
            @Html.ValidationMessageFor(model => model.Employee.EmployeeSalariedFlag, "", new { @class = "text-danger" })
        </div>
    </div>



    <div class="form-group">
        <div class="col-md-offset-2 col-md-10">
            <input type="submit" value="Guardar" class="btn btn-default" />
        </div>
    </div>
    <div class="form-group">
        <div class="col-md-offset-2 col-md-10" style="color:green">
            @ViewBag.Message
        </div>
        <div class="col-md-offset-2 col-md-10" style="color:red">
            @ViewBag.ErrorMessage
        </div>
    </div>
</div>


}