关于c＃：从List＆lt; object＆gt;填充剃刀下拉列表


Populating a razor dropdownlist from a List<object> in MVC

我有一个模型：

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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;
        }
    }

这里是加载视图的控制器：

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        //
        // GET: /Admin/AddNewUser

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

我可以使用@foreach循环获取列表中的项目，如下所示：

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

但是如何用传递的模型填充DropDownList，我已经尝试过了

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

但我运气不好。

您可以将业务逻辑分离为一个视图模型，这样您的视图就有了更清晰的分离。

首先创建一个viewModel来存储用户将选择的ID以及将出现在DropDown中的项目列表。

ViewModel：

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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; }
}

参考文献：

  • DisplayAttribute

在控制器内部，创建一个方法来获取您的UserRole列表，并将其转换为将在视图中显示的形式。

控制器：

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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);
}

参考文献：

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

现在创建了视图模型，表示逻辑就简化了

观点：

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@model UserRoleViewModel

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

参考文献：

  • LabelExtensions.LabelFor
  • SelectExtensions.DropDownListFor

这将产生：

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<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>
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  @Html.DropDownList("ddl",Model.Select(item => new SelectListItem
{
    Value = item.RecordID.ToString(),
    Text = item.Name.ToString(),
     Selected ="select" == item.RecordID.ToString()
}))
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一种可能是；

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

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

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

您需要一个SelectList来填充DropDownListfor。对于所需的任何HTML属性，可以添加：

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

您可以让您的模型包含一个SelectList，而不是List。同时添加一个属性SelectedUserRoleId来存储…好。。。所选用户角色的ID值。

填写选择列表，然后在视图中使用：

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

你应该没事的。

另请参见http://msdn.microsoft.com/en-us/library/system.web.mvc.selectlist(v=vs.108).aspx。

你对DropDownListFor的调用需要更多的参数来充实它。您需要一个选择列表，如下面的问题所示：

MVC3 DropDownListfor-一个简单的例子？

有了这些，您只告诉它在哪里存储数据，而不是从哪里加载列表。

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   @{
        List<CategoryModel> CategoryList = CategoryModel.GetCategoryList(UserID);
        IEnumerable<SelectListItem> CategorySelectList = CategoryList.Select(x => new SelectListItem() { Text = x.CategoryName.Trim(), Value = x.CategoryID.Trim() });
    }
    <tr>
        <td>
            Assigned Category:
        </td>
        <td>
            @Html.DropDownList("CategoryList", CategorySelectList,"Select a Category (Optional)")
        </td>
    </tr>
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我将把这当作一个用户模型来处理：

用户服务系统

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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; }
}

以及在数据库中用该名称表示表的dbuserroles模型：

德布罗洛斯

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

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

清理完之后，您应该能够在控制器中创建和填充一组用户角色，如：

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

并具有以下支持功能：

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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();
}

知识库

我的存储库函数GetAllUserRoles()用于函数，上面：

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

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

添加新用户.cshtml

然后在您的视图中执行此操作：

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

Ingresar Usuario

@using (Html.BeginForm())
{

    @Html.AntiForgeryToken()



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

   
        @Html.LabelFor(model => model.Employee.PersonType, labelText:"Tipo de Persona", htmlAttributes: new { @class ="control-label col-md-2" })
       
            @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" })
       
   

   
        @Html.LabelFor(model => model.Employee.EmployeeGender, labelText:"Genero", htmlAttributes: new { @class ="control-label col-md-2" })
       
            @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" })
       
   

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

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

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

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

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

   
        @Html.LabelFor(model => model.Employee.DepartmentID, labelText:"Departamento", htmlAttributes: new { @class ="control-label col-md-2" })
       
            @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" })
       
   


   
        @Html.LabelFor(model => model.Employee.EmployeeMaritalStatus, labelText:"Estado Civil", htmlAttributes: new { @class ="control-label col-md-2" })
       
            @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" })
       
   

   
        @Html.LabelFor(model => model.Employee.ShiftId, labelText:"Turno", htmlAttributes: new { @class ="control-label col-md-2" })
       
            @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" })
       
   



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

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

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

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

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



   
       
            <input type="submit" value="Guardar" class="btn btn-default" />
       
   
   
       
            @ViewBag.Message
       
       
            @ViewBag.ErrorMessage
       
   



}
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