Question

我对MVC很新，所以请耐心等待，但是我似乎无法在MVC 4回发期间将SelectList中的值绑定到所选对象的实例。

假设我必须创建一名教师作为学校的成员。我有一个ViewModel类定义如下：

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中的Create方法中收到RegisterTeacherModel对象时，SelectedSchool总是为null。我必须错过模型绑定器在回发时重新创建对象引用的方式。有人能指出我正确的方向吗？

Answer 1

我想你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>

Answer 2

好吧，我找到了解决方法。我仍然不知道我是否遗漏了某些内容，但我没有在ViewModel中使用School对象，而是将其替换为SelectedSchoolId：

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 int SelectedSchoolId { get; set; }

    ...
}

并更改我的“查看”下拉列表以改为使用此选项：

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

然后在我的控制器中，在创建真实模型对象时，我可以简单地从School存储库中取出School对象，并将其与真正的Teacher对象相关联。

将SelectedItem从下拉列表绑定到MVC 4中的模型对象

2 个答案: