如何从 asp.net MVC 4 中的选择列表中获取项目

本文关键字：选择 获取 项目 列表 asp net MVC | 更新日期: 2023-09-27 17:56:40

我正在创建一个自定义注册表单，仅供站点管理员在此注册表中使用，管理员可以添加用户并赋予他们在站点中的角色，因此我制作了此模型来定义 

public class AddUserToRoleModels
{
    [Required]
    [Display(Name = "User name")]
    public string UserName { get; set; }
    [Required]
    [StringLength(100, ErrorMessage = "The {0} must be at least {2} characters long.", MinimumLength = 6)]
    [DataType(DataType.Password)]
    [Display(Name = "Password")]
    public string Password { get; set; }
    [Required]
    [DataType(DataType.Password)]
    [Display(Name = "Confirm password")]
    [Compare("Password", ErrorMessage = "The password and confirmation password do not match.")]
    public string ConfirmPassword { get; set; }
    [Required]
    [Display(Name = "Select Role")]
    public string Roles { get; set; }
}

并在类函数中使此方法添加用户并赋予他们角色

public class Functions
{
    public void AddUserToRole(string UserName,string PassWord,string Role) {
        if (!WebSecurity.UserExists(UserName))
            WebSecurity.CreateUserAndAccount(UserName, PassWord);
        if (!Roles.GetRolesForUser(UserName).Contains(Role))
            Roles.AddUsersToRoles(new[] { UserName }, new[] { Role });
    }
}

然后我创建这个控制器

public class AddUserToRoleController : Controller
{
    UsersContext db = new UsersContext();
    public ActionResult Create()
    {
        ViewBag.RoleId = new SelectList(db.Roles, "RoleId", "RoleName");
        return View();
    }
    [HttpPost]
    public ActionResult Create(AddUserToRoleModels model)
    {
        if (ModelState.IsValid)
        {
            Functions ob = new Functions();
            ob.AddUserToRole(model.UserName, model.Password, model.Roles);
            return RedirectToAction("Index");
        }
        ViewBag.RoleId = new SelectList(db.Roles, "RoleId", "RoleName");
            return View(model);
    }
 }

并为创建操作控制器创建视图 

@model SeniorProject.Models.AddUserToRoleModels
@{
    ViewBag.Title = "Create";
}
 <h2>Create</h2>
 @using (Html.BeginForm()) {
@Html.ValidationSummary(true)
<fieldset>
    <legend>AddUserToRoleModels</legend>
    <div class="editor-label">
        @Html.LabelFor(model => model.UserName)
    </div>
    <div class="editor-field">
        @Html.EditorFor(model => model.UserName)
        @Html.ValidationMessageFor(model => model.UserName)
    </div>
    <div class="editor-label">
        @Html.LabelFor(model => model.Password)
    </div>
    <div class="editor-field">
        @Html.EditorFor(model => model.Password)
        @Html.ValidationMessageFor(model => model.Password)
    </div>
    <div class="editor-label">
        @Html.LabelFor(model => model.ConfirmPassword)
    </div>
    <div class="editor-field">
        @Html.EditorFor(model => model.ConfirmPassword)
        @Html.ValidationMessageFor(model => model.ConfirmPassword)
    </div>
    <div class="editor-label">
        @Html.LabelFor(model => model.Roles)
    </div>
    <div class="editor-field">
        @Html.DropDownList("RoleId", String.Empty)
        @Html.ValidationMessageFor(model => model.Roles)
    </div>
    <p>
        <input type="submit" value="Create" />
    </p>
</fieldset>
  }
<div>
   @Html.ActionLink("Back to List", "Index")
</div>
 @section Scripts {
   @Scripts.Render("~/bundles/jqueryval")
}

当我尝试添加新用户并赋予他角色时，用户插入到数据库中但没有角色，我认为因为我试图从@Html.DropDownList("RoleId", String.Empty)中获取角色，它是列表和我的方法，它需要字符串参数作为角色，我尝试从此列表中获取所选项目，但没有有效的以太，所以请帮助...

如何从 asp.net MVC 4 中的选择列表中获取项目

@Html.DropDownListFor(model => model.RoleID, ViewBag.RoleID, "")

或类似的东西。

您还可以将列表作为 selectList 放入视图模型中，然后将其称为 Model.RoleID

试试这个：

public ActionResult Create()
{
    ViewBag.Roles = new SelectList(db.Roles, "RoleId", "RoleName");
    return View();
}

在视图： 

@Html.DropDownListFor(model => model.RoleId, ViewBag.Roles as IEnumerable<SelectListItem>, "Select a role" )

在"发布操作if(model.RoleId == 0)"中，因此不选择任何角色。

控制器

中的

using （UsersContext db = new UsersContext（））{    var tmp = db。Roles.ToList（）;    ViewBag.RoleId = new SelectList（tmp， "RoleId"， "RoleName"）;}

在视图中

@Html.DropDownListFor(model => model.RoleID, (SelectList)@ViewBag.RoleId)
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