asp.net-mvc-3 - 在 mvc 的下拉列表中使用外键

Question

我是 MVC 新手，并且一直坚持一个应该是非常简单的问题。我正在处理this tutorial一切都非常正常，除了我现在想添加一个外键“链接”(不确定它叫什么)，但似乎无法让它工作。这是我所拥有的:

表格:

 Inventory:
 Id   |  SerialNumber  | ManufacturerId (foreignkey to Manufactueres->id)

 Manufactureres
 Id (primary key)   |  Name

模型(InventoryItem.cs):

 public class InventoryItem {
     public int Id {get; set; }
     public int SerialNumber{ get; set; }

     //this starts the trouble, I actually want to interact with the Manufactureres table -> Name column
     public int ManufacturerId { get; set; }  
 }

查看(Create.cshtml):

 ...
 //What i really want is a dropdown of the values in the Manufactureres table
 @Html.EditorFor(model=> model.ManufacturerId)

这一定是使用关系数据库时的一个常见问题，会使用/显示许多外键关系，但由于某种原因，我在 stackoverflow 上找不到直接对应于如此简单的内容的教程或问题。非常感谢任何指导或方向!谢谢，

Answer 1

我希望我正确理解你的问题。似乎当您想要添加新的库存项目时，您需要在下拉列表中列出所有制造商的列表。我将致力于这个假设，如果我偏离了轨道，请告诉我:)

首先创建一个 View 模型。您将将此 View 模型绑定(bind)到您的 View 。切勿将域对象绑定(bind)到您的 View 。

public class InventoryItemViewModel
{
     public int SerialNumber { get; set; }

     public int ManufacturerId { get; set; }

     public IEnumerable<Manufacturer> Manufacturers { get; set; }
}

您的域对象:

public class InventoryItem
{
     public int Id { get; set; }

     public int SerialNumber{ get; set; }

     public int ManufacturerId { get; set; }
}

public class Manufacturer
{
     public int Id { get; set; }

     public string Name { get; set; }
}

您的 Controller 可能如下所示:

public class InventoryItemController : Controller
{
     private readonly IManufacturerRepository manufacturerRepository;
     private readonly IInventoryItemRepository inventoryItemRepository;

     public InventoryItem(IManufacturerRepository manufacturerRepository, IManufacturerRepository manufacturerRepository)
     {
          // Check that manufacturerRepository and inventoryItem are not null

          this.manufacturerRepository = manufacturerRepository;
          this.inventoryItemRepository = inventoryItemRepository;
     }

     public ActionResult Create()
     {
          InventoryItemViewModel viewModel = new InventoryItemViewModel
          {
               Manufacturers = manufacturerRepository.GetAll()
          };

          return View(viewModel);
     }

     [HttpPost]
     public ActionResult Create(InventoryItemViewModel viewModel)
     {
          // Check that viewModel is not null

          if (!ModelState.IsValid)
          {
               Manufacturers = manufacturerRepository.GetAll()

               return View(viewModel);
          }

          // All validation is cool

          // Use a mapping tool like AutoMapper
          // to map between view model and domain model
          InventoryItem inventoryItem = Mapper.Map<InventoryItem>(viewModel);

          inventoryItemRepository.Insert(inventoryItem);

          // Return to which ever view you need to display
          return View("List");
     }
}

然后在您看来，您可能会遇到以下情况:

@model MyProject.DomainModel.ViewModels.InventoryItems.InventoryItemViewModel

<table>
     <tr>
          <td class="edit-label">Serial Number <span class="required">**</span></td>
          <td>@Html.TextBoxFor(x => x.SerialNumber, new { maxlength = "10" })
              @Html.ValidationMessageFor(x => x.SerialNumber)
          </td>
     </tr>
     <tr>
          <td class="edit-label">Manufacturer <span class="required">**</span></td>
          <td>
               @Html.DropDownListFor(
                    x => x.ManufacturerId,
                    new SelectList(Model.Manufacturers, "Id", "Name", Model.ManufacturerId),
                    "-- Select --"
               )
               @Html.ValidationMessageFor(x => x.ManufacturerId)
          </td>
     </tr>
</table>

我希望这有帮助:)