如何使用 HTML 表单传递整个对象？

Question

为简单起见，我将只包括模型的相关属性和相关行：

型号：Department.cs
属性：public virtual Staff HOD { get; set; }

控制器方法：

[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Add([Bind] Department newDepartment)
{
    await _departmentRepository.AddDepartmentAsync(newDepartment);
    await _departmentRepository.SaveTransactionAsync(true);
    return Redirect("Details" + "/" + newDepartment.Id);
}

查看：

@model Department
@inject IStaffRepository staffRepository

@{
    // select list
    var listOfEmployees = new List<Staff>();
    foreach (var staff in await staffRepository.GetAllStaffAsync())
    {
        listOfEmployees.Add(staff);
    }
    var selectListHOD = new SelectList(listOfEmployees, "EmployeeId", "Name"); //populates the option element with the correct Employee Id
}

<form class="form-group" method="post">
    <div class="d-flex flex-column">
        <div class="input-group" style="margin-bottom: 1%">
            @Html.DropDownListFor(department => department.HOD, selectListHOD, htmlAttributes: new { @class="form-control" })
        </div>
        <div class="input-group">
            <input class="btn btn-primary" type="submit" value="Save" />
        </div>
    </div>
</form>

结果：
（我没有在问题中包含此处看到的其他属性，但请相信我，控制器参数的属性会正确填充它们，HOD 属性除外）

---

来源：

<form class="form-group" method="post">
    <div class="d-flex flex-column">
        <div class="input-group" style="margin-bottom: 1%">
            <input class="form-control" id="Id" name="Id" placeholder="Id" type="text" value="" /> </div>
        <div class="input-group" style="margin-bottom: 1%">
            <input class="form-control" id="Name" name="Name" placeholder="Department" type="text" value="" /> </div>
        <div class="input-group" style="margin-bottom: 1%">
            <input class="form-control" id="Description" name="Description" placeholder="Description" type="text" value="" /> </div>
        <div class="input-group" style="margin-bottom: 1%">
            <select class="form-control" id="HOD" name="HOD">
                <option value="EMP01">Employee 1</option>
                <option value="EMP02">Employee 2</option>
            </select>
        </div>
        <div class="input-group">
            <input class="btn btn-primary" type="submit" value="Save" /> </div>
    </div>
    <input name="__RequestVerificationToken" type="hidden" value="CfDJ8AIwSWkSO0hJqMxy-oQKoeG35LTDmI2N1XHDZL9qeaxRxc17TyZbT2z9Iq0GMPkRyE7HnaX1r4ZSIs0bQATYB7w_A_HZDBXGETMmpdSqlMXZCmf7cH9ECzrNGz0Wuu9zHkE50yI92vPY-GxNPG-pRhs" /> 
</form>

我的猜测是提供给控制器的值似乎是错误的。我将如何传递实际对象而不是 ID？
我尝试使用this 代替EmployeeId，但它会抛出Object Reference not found 异常。

Answer 1

您不能将对象与<select></select>。您可以尝试用<select></select> 987654326 @ .and添加一个隐藏的输入来绑定Hod.Name。选定的值更改时，更改隐藏的输入值。是一个演示：

<form class="form-group" method="post">
    <div class="d-flex flex-column">
        <div class="input-group" style="margin-bottom: 1%">
            @Html.DropDownListFor(department => department.HOD.EmployeeId, selectListHOD, htmlAttributes: new { @class = "form-control",@onChange= "AddName()" })
            <input hidden asp-for="HOD.Name" />
        </div>
        <div class="input-group">
            <input class="btn btn-primary" type="submit" value="Save" />
        </div>
    </div>
</form>
@section scripts
{
    <script>
        $(function () {
            AddName();
        })
        function AddName() {
            $("#HOD_Name").val($("#HOD_EmployeeId option:selected").text());
        }
    </script>
}

结果：