使用Razor中的HTML Actionlink从IEnumerable类型的视图传递ID

Question

我有两个模型“计算机”和“计算机详细信息”。 用户可以从“计算机的索引”页面中单击给定记录的“查看详细信息”，该记录将重定向到“计算机详细信息的索引”，并使用查询字符串获取与给定的“计算机ID”相关联的所有记录-正常工作

我的问题是我想要一个“创建”链接，该链接带有此“计算机ID”（在视图中显示）并填充“创建”表单上的“计算机ID”字段。

我使用了Model.First（）。ComputerID来运行带有一些测试记录的代码，但是如果ComputerID的记录为null，则它当然不起作用。

视图

@modelIEnumerable<MyApp.Models.ComputerDetail>
@{
     ViewBag.Title = "Index";
 }

 <h2 class ="page-header">Computer Details</h2>

 <div class ="col-lg-12">
     <p>
           @Html.ActionLink("Create New", "Create", "ComputerDetail", new {id = Model.First().ComputerID}, new { @class = "btn btn-default"})
     </p>
<div class="panel panel-default">
    <div class ="panel-body">
        <table class ="table table-striped" id="dtaTable">
            <thead class ="dataTableHead">
                <tr>
                    <th>
                        @Html.DisplayNameFor(model => model.ComputerID)
                    </th>
                    <th>
                        @Html.DisplayNameFor(model => model.EmployeeID)
                    </th>
                    <th>
                        @Html.DisplayNameFor(model => model.StartDate)
                    </th>
                    <th>
                        @Html.DisplayNameFor(model => model.EndDate)
                    </th>
                    <th>
                        @Html.DisplayNameFor(model => model.Comments)
                    </th>
                    <th>Actions</th>
               </tr>
        </thead>

    @foreach (var item in Model) {
                <tr>
                    <td>
                        @Html.DisplayFor(modelItem => item.ComputerID)
                    </td>
                    <td>
                        @Html.DisplayFor(modelItem => item.Employee.FullName)
                    </td>
                    <td>
                        @Html.DisplayFor(modelItem => item.StartDate)
                    </td>
                    <td>
                        @Html.DisplayFor(modelItem => item.EndDate)
                    </td>
                    <td>
                        @Html.DisplayFor(modelItem => item.Comments)
                    </td>
                    <td>
                        @Html.ActionLink("Edit", "Edit", new { id=item.ID }) |
                        @Html.ActionLink("Details", "Details", new { id=item.ID }) |
                        @Html.ActionLink("Delete", "Delete", new { id=item.ID })
                    </td>
                </tr>
}
            </table>
        </div>
    </div>
</div>

控制者

public ActionResult Index(int id)
    {
        var _FindComputerID = GetComputerDetails(id);
        return View(_FindComputerID);
    }

    private List<ComputerDetail>GetComputerDetails(int id)
    {
        var FindComputerID = db.ComputerDetails.Where(cd => cd.ComputerID == id).Include
                    (cd => cd.Employee).OrderByDescending(cd => cd.ID);

        return FindComputerID.ToList();
    }

    [HttpGet]
    public ActionResult Create(int id)
    {
        ComputerDetail computerdetail = new ComputerDetail ();
        computerdetail.ComputerID = id;

        return View(computerdetail);
    }

模型

public class ComputerDetail
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int ID { get; set; }

    [Required(ErrorMessage = "Please enter service tag")]
    [Display(Name = "Service Tag")]
    public int ComputerID { get; set; }

    [Required(ErrorMessage = "Please select employee name")]
    [Display(Name = "Employee Name")]
    public int EmployeeID { get; set; }

    [Required(ErrorMessage = "Please enter date")]
    [Display(Name = "Date Bought")]
    [DataType(DataType.Date)]
    public DateTime StartDate { get; set; }

    [Display(Name = "Date Bought")]
    [DataType(DataType.Date)]
    public DateTime? EndDate { get; set; }

    public string Comments { get; set; }

    //references
    public virtual Assets.Computer Computer { get; set; }
    public virtual Employee Employee { get; set; }

}

Answer 1

这里发生了两件事：

首先，如果您的视图需要获取ComputerID，则可能需要在ViewModel中反映此字段，而不是从列表的第一项中获取该字段。

public class ComputerDetailsViewModel
{
    public int ComputerID {get; set;} // populate in the action directly
    public IEnumerable<MyApp.Models.ComputerDetail> Items {get; set;}
}

您确实想走这条路，应该使用nullable运算符进行更好的错误处理，以弄清ComputerID为null时会发生什么。

@Html.ActionLink("Create New", "Create", "ComputerDetail", new {id = Model.FirstOrDefault()?.ComputerID ?? 0 /*Null case*/}, new { @class = "btn btn-default"})

希望有帮助！