asp.net-mvc - 将下拉列表中的 SelectedItem 绑定(bind)到 MVC 4 中的模型对象

Question

我对 MVC 很陌生，所以请耐心等待，但在 MVC 4 的回发期间，我似乎无法将 SelectList 中的值绑定(bind)到所选对象的实例。

假设我必须创建一个教师作为学校的成员。我有一个这样定义的 ViewModel 类:

public class RegisterTeacherModel
{
    [Required]
    [Display(Name = "User name")]
    public string UserName { get; set; }

    [Required]
    [DataType(DataType.EmailAddress)]
    [Display(Name = "Email address")]
    public string Email { get; set; }

    [Required]
    [Display(Name = "School")]
    public School SelectedSchool { get; set; }

    [ScaffoldColumn(false)]
    public Guid UserId
    {
        get;
        set;
    }

    public SelectList PossibleSchools
    {
        get;
        private set;
    }

    public RegisterTeacherModel(IRepository<School> schoolRepo)
    {
        PossibleSchools = new SelectList(schoolRepo, "Id", "Name");
    }
}

我的观点:

@using (Html.BeginForm()) {
@Html.ValidationSummary(true)

<fieldset>
    <legend>RegisterTeacherModel</legend>

    <div class="editor-label">
        @Html.LabelFor(model => model.UserName)
    </div>

    <div class="editor-label">
        @Html.LabelFor(model => model.Email)
    </div>
    <div class="editor-field">
        @Html.EditorFor(model => model.Email)
        @Html.ValidationMessageFor(model => model.Email)
    </div>

    <div class="editor-label">
        @Html.LabelFor(model => model.SelectedSchool)
    </div>
    <div class="editor-field">
        @Html.DropDownListFor(model => model.SelectedSchool, Model.PossibleSchools)
    </div>
    <p>
        <input type="submit" value="Create" />
    </p>
</fieldset>
}

最后，我的 Controller 方法:

    [HttpPost, ActionName("Create")]
    public ActionResult CreateTeacher(RegisterTeacherModel teacherModel)
    {
        if (ModelState.IsValid)
        {
            try
            {
              ...
            }
         }
    }

但是，当我在 Controller 的 Create 方法中收到 RegisterTeacherModel 对象时，SelectedSchool 始终为空。我必须在模型绑定(bind)器在回发时重新创建对象引用的方式上遗漏了一些东西。谁能指出我正确的方向？

Answer 1

我认为您在第二篇文章中提到了它:尝试将初始代码指向 Model.SelectedSchool。 <IdProperty>

<div class="editor-field">
  @Html.DropDownListFor(model => model.SelectedSchool.**<IdProperty>**, Model.PossibleSchools)
</div>