在我的项目中，我首先使用ASP.Net 4.0 Entity Framework数据库。 我有2个带有外键和View Model的Entity类，示例如下：
光纤类：
namespace fibresInTexilesMvc.Models
{
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
public partial class fibre
{
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
public fibre()
{
this.products = new HashSet<product>();
}
public int FiberId { get; set; }
public string Name { get; set; }
public string Category { get; set; }
public string Picture1 { get; set; }
public string Description { get; set; }
public string Advantages { get; set; }
public string Disadvantages { get; set; }
public string Picture2 { get; set; }
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
public virtual ICollection<product> products { get; set; }
}
}
产品类：
namespace fibresInTexilesMvc.Models
{
using System;
using System.Collections.Generic;
public partial class product
{
public int ProductId { get; set; }
public string Name { get; set; }
public string Picture { get; set; }
public string Overview { get; set; }
public int FiberId { get; set; }
public virtual fibre fibre { get; set; }
}
}
查看Model.cs
namespace fibresInTexilesMvc.ViewModels
{
public class FibAndProdViewModel
{
public int FiberId { get; set; }
public string Picture1 { get; set; }
public string Description { get; set; }
public string Advantages { get; set; }
public string Disadvantages { get; set; }
public string Picture2 { get; set; }
public string Picture { get; set; }
public string Name { get; set; }
}
}
我希望在ViewModel中收到有关所选光纤和所有相关产品的详细信息。
在 Home Controller 中，我创建了操作方法：
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Entity;
using System.Linq;
using System.Net;
using System.Web;
using System.Web.Mvc;
using fibresInTexilesMvc.Models;
using fibresInTexilesMvc.ViewModels;
{
//GET: Home/FiberAndProducts/5
public ActionResult FiberAndProducts(int? FiberId)
{
List<fibre> fibandprodlist = db.fibres.ToList();
List<FibAndProdViewModel> fibandprodVmList = fibandprodlist
.Select(x => new FibAndProdViewModel()
{
FiberId = x.FiberId,
Picture1 = x.Picture1,
Description = x.Description,
Advantages = x.Advantages,
Disadvantages = x.Disadvantages,
Picture2 = x.Picture2,
Picture = x.products.Select(a => a.Picture).SingleOrDefault(),
Name = x.products.Select(a => a.Name).SingleOrDefault()
}).ToList();
return View(fibandprodVmList);
}
}
当我在浏览中打开它时会显示以下错误： Error in program
这个错误可能与收集属性有关，例如＆＃39;图片＆＃39;和＆＃39;姓名＆＃39;当我评论这两个属性时，我可以看到桌子上的所有纤维，但它不是我需要的。我需要的是，当我按下特定光纤链接时，它应该显示另一个查看有关光纤的详细信息，并从db.products获取所有相关产品。 我不知道如何解决这个问题。 以下是：
@model IEnumerable<fibresInTexilesMvc.ViewModels.FibAndProdViewModel>
@{
Layout = null;
}
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width" />
<title>FiberAndProducts</title>
</head>
<body>
<p>
@Html.ActionLink("Create New", "Create")
</p>
<table class="table">
<tr>
<th>
@Html.DisplayNameFor(model => model.FiberId)
</th>
<th>
@Html.DisplayNameFor(model => model.Picture1)
</th>
<th>
@Html.DisplayNameFor(model => model.Description)
</th>
<th>
@Html.DisplayNameFor(model => model.Advantages)
</th>
<th>
@Html.DisplayNameFor(model => model.Disadvantages)
</th>
<th>
@Html.DisplayNameFor(model => model.Picture2)
</th>
<th>
@Html.DisplayNameFor(model => model.Picture)
</th>
<th>
@Html.DisplayNameFor(model => model.Name)
</th>
<th></th>
</tr>
@foreach (var item in Model) {
<tr>
<td>
@Html.DisplayFor(modelItem => item.FiberId)
</td>
<td>
@Html.DisplayFor(modelItem => item.Picture1)
</td>
<td>
@Html.DisplayFor(modelItem => item.Description)
</td>
<td>
@Html.DisplayFor(modelItem => item.Advantages)
</td>
<td>
@Html.DisplayFor(modelItem => item.Disadvantages)
</td>
<td>
@Html.DisplayFor(modelItem => item.Picture2)
</td>
<td>
@Html.DisplayFor(modelItem => item.Picture)
</td>
<td>
@Html.DisplayFor(modelItem => item.Name)
</td>
<td>
@Html.ActionLink("Edit", "Edit", new { /* id=item.PrimaryKey */ }) |
@Html.ActionLink("Details", "Details", new { /* id=item.PrimaryKey */ }) |
@Html.ActionLink("Delete", "Delete", new { /* id=item.PrimaryKey */ })
</td>
</tr>
}
</table>
</body>
</html>
最重要的是我对图片有疑问。使用自定义HTMLHelper（@ Html.Image（@ Model.Picture1））将图片路径从数据库渲染到View I＆＃39; m。它在“细节”中显示图片。查看，但是当我在ViewModel中使用IEnumerable时，它会向我显示Compailer Error：＆＃34;编译器错误消息：CS1061：＆＃39; IEnumerable＆＃39;不包含＆＃39; Picture1＆＃39;的定义没有扩展方法＆＃39; Picture1＆＃39;接受类型＆＃39; IEnumerable＆＃39;的第一个参数。可以找到（你错过了使用指令或程序集引用吗？）＆＃34;。 当我有IEnumerable或ICollection时如何使用CustomHTMLHelper？
CustomHtmlHelper.cs的代码：
namespace fibresInTexilesMvc.CustomHtmlHelper
{
public static class CustomHtmlHelper
{
public static IHtmlString Image(this HtmlHelper helper, string src)
{
//Build <img> tag
TagBuilder tb = new TagBuilder("img");
//Ad "src" attribute
tb.Attributes.Add("src", VirtualPathUtility.ToAbsolute(src));
//return MvcHtmlString. This class implements IHtmlString
//interface. IHTMLString will not be html encoded.
return new MvcHtmlString(tb.ToString(TagRenderMode.SelfClosing));
}
}
}
答案 0 :(得分：0)
在控制器中
Picture = x.products.Select(a => a.Picture).SingleOrDefault(),
Name = x.products.Select(a => a.Name).SingleOrDefault()
应该改为
Products = x.products
在你的FibAndProdViewModel中添加
ICollection<product> Products { get; set; }
喜欢这个
namespace fibresInTexilesMvc.ViewModels
{
public class FibAndProdViewModel
{
public int FiberId { get; set; }
public string Picture1 { get; set; }
public string Description { get; set; }
public string Advantages { get; set; }
public string Disadvantages { get; set; }
public string Picture2 { get; set; }
public string Picture { get; set; }
public string Name { get; set; }
ICollection<product> Products { get; set; }
}
}
在视图中这个
<td>
@Html.DisplayFor(modelItem => item.Picture)
</td>
<td>
@Html.DisplayFor(modelItem => item.Name)
</td>
应该改为
<table>
@foreach (var product in item.Products) {
<tr>
<td>
@Html.DisplayFor(modelItem => product.Picture)
</td>
<td>
@Html.DisplayFor(modelItem => product.Name)
</td>
</tr>
}
</table>