Question

我对MVC 5和网络编程都很陌生，所以请耐心等待。

我有一个视图（用于管理用户角色），我有三个单独的表单，我或多或少地从教程中复制和粘贴。在本教程中，表单的字段按以下方式创建：

Username : @Html.TextBox("Username")

由于我希望样式适合他们，我将代码更改为更像MVC 5模板中的默认表单，所以最终看起来像这样：

@Html.LabelFor(m => m.GetRolesUsername, new { @class = "col-md-2 control-label" })
                    <div class="col-md-10">
                        @Html.TextBoxFor(m => m.GetRolesUsername, new { @class = "form-control" })
                        @Html.ValidationMessageFor(m => m.GetRolesUsername, "", new { @class = "text-danger" })
                    </div>

我的模型ManageUserRolesViewModel看起来像这样（请注意，在我的视图顶部，我有@model ManageUserRolesViewModel）：

public class ManageUserRolesViewModel
{
    #region Assign Role
    [Required]
    [Display(Name = "Username", ResourceType = typeof(Resources))]
    public string AssignRoleUsername { get; set; }

    [Required]
    [Display(Name = "RoleName", ResourceType = typeof(Resources))]
    public string AssignRoleRole { get; set; }
    #endregion

    #region Get Roles
    [Required]
    [Display(Name = "Username", ResourceType = typeof(Resources))]
    public string GetRolesUsername { get; set; }
    #endregion

    #region Unassign Role
    [Required]
    [Display(Name = "Username", ResourceType = typeof(Resources))]
    public string UnassignRoleUsername { get; set; }

    [Required]
    [Display(Name = "RoleName", ResourceType = typeof(Resources))]
    public string UnassignRoleRole { get; set; }
    #endregion
}

请注意我是如何使用注释直接从资源加载ViewModel中元素的名称的。我这样做是出于本地化的目的，资源正在用西班牙语返回字符串。 我认为这可能是我问题的根源，但我不确定。

然后，在我的控制器中，我有以下方法：

        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult GetRoles(string UserName)
        {
            if (!string.IsNullOrWhiteSpace(UserName))
            {
                ApplicationUser user = context.Users.Where(u => u.UserName.Equals(UserName, StringComparison.CurrentCultureIgnoreCase)).FirstOrDefault();

                ViewBag.RolesForThisUser = this.UserManager.GetRoles(user.Id);
                ViewBag.Roles = context.Roles.OrderBy(r => r.Name).ToList().Select(rr => new SelectListItem { Value = rr.Name.ToString(), Text = rr.Name }).ToList();
            }

            return View("ManageUserRoles");
        }

现在，发生了什么：如果我使用Username : @Html.TextBox("Username")，当在控制器中调用方法GetRoles()时，UserName参数就在那里并且用户成功加载。相反，我使用

@Html.LabelFor(m => m.GetRolesUsername, new { @class = "col-md-2 control-label" })
                    <div class="col-md-10">
                        @Html.TextBoxFor(m => m.GetRolesUsername, new { @class = "form-control" })
                        @Html.ValidationMessageFor(m => m.GetRolesUsername, "", new { @class = "text-danger" })
                    </div>

调用方法时，UserName参数为null。

我的猜测是，代码MVC中的某处正在寻找UserName或Username并找到Usuario，但我不确定这是否属实，无论如何，我想知道如何解决这个问题。

Answer 1

假设您的表单将模型定义为：

@model ManageUserRolesViewModel

和视图中的某个地方：

@Html.TextBoxFor(m => m.GetRolesUsername, new { @class = "form-control" })

行动应如下所示：

[HttpPost]
public ActionResult GetRoles(ManageUserRolesViewModel vm)
{
    string userName = vm.GetRolesUsername;
    //rest of code omitted.
}

因此，您不依赖于UserName参数，并且可以使用视图模型本身。

如果这还不够，你可以这样做：

@Html.TextBoxFor(x => x.GetRolesUsername, new { Name = "UserName" })

Answer 2

Hi Eric,

    @Html.TextBox("Username")
    // It creates a html input element with name "Username"
    <input type="text" id=""Username" name="Username" value="" />

And 

    @Html.TextBoxFor(m => m.GetRolesUsername)
    // It also create a html element with name as it's property name. ie, "GetRolesUsername"
    <input type="text" id=""Username" name="Username" value="@Model.GetRolesUsername" />

    So, if you submit your form, your browser will send parameters as,


    Username = "value in the @html.TeaxtBox()",
    GetRolesUsername = "value in the @html.TextBoxFor()"


So, both values will be passed to your MVC controller. Then you can decide what parameters you want to receive.

    public ActionResult Submit(string Username, string GetRolesUsername)
    {
        // You can get Username and GetRolesUsername here
    }

    public ActionResult Submit(string Username)
    {
        // You tell your controller that I am expecting only one parameter and that is Username
    }

Then there will be a main difference between `@html.TextBox()` and `@html.TextBoxFor()' is, 

`@html.TextBox()` will just create a text element. But, `@html.TextBoxFor()' will create and set value to the element.

Hope this will help you.

If you have any doubts, please feel free to ask me.

**And Grand Welcome To MVC.**

I am also just a beginner in MVC :)

Html.Textbox工作在哪里Html.TextboxFor不是？

2 个答案: