从MVC中的List <object>填充razor下拉列表

Question

我有一个模特:

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;
        }
    }

这是加载视图的Controller:

        //
        // GET: /Admin/AddNewUser

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

我可以使用@foreach循环显示列表中的项目,如下所示:

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

但是我如何使用传递的模型填充下拉列表,我尝试过

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

但我没有运气.

Answer 1

您可以将业务逻辑分离到视图模型中,这样您的视图就可以更清晰地分离.

首先创建一个viewmodel来存储用户将选择的Id以及将出现在其中的项目列表DropDown.

视图模型:

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UserRole列表并将其转换为将在视图中显示的表单.

控制器:

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,简化了表示逻辑

视图:

@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:

<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>

Answer 2

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

Answer 3

一种方式可能是;

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

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

Answer 4

接近的东西:

@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.对于您需要的任何HTML属性,您可以添加:

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

Answer 5

List<UserRole>您可以让模型包含a 而不是a SelectList<UserRole>.还要添加一个属性SelectedUserRoleId来存储......以及所选的UserRole的Id值.

填写SelectList,然后在View中使用:

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

你应该没事

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