如何在 ASP.NET MVC 4 中正确使用元组

Question

我正在尝试使用元组在一个视图中使用两个模型，但出现此错误： “/”应用程序中的服务器错误。

传入字典的模型项的类型为“PagedList.PagedList1[S00117372CA3.Product]', but this dictionary requires a model item of type 'System.Tuple2[PagedList.IPagedList1[S00117372CA3.Product],System.Collections.Generic.IEnumerable1[S00117372CA3.Order]]”。

说明：在执行当前 Web 请求期间发生未处理的异常。请查看堆栈跟踪以获取有关错误及其源自代码的位置的更多信息。

异常详情：System.InvalidOperationException：传入字典的模型项的类型为“PagedList.PagedList1[S00117372CA3.Product]', but this dictionary requires a model item of type 'System.Tuple2[PagedList.IPagedList1[S00117372CA3.Product],System.Collections.Generic.IEnumerable1[S00117372CA3.Order]]”。

这是我的代码：

    @*@model PagedList.IPagedList<S00117372CA3.Product>*@
@model Tuple<PagedList.IPagedList<S00117372CA3.Product>, IEnumerable<S00117372CA3.Order>>
@{
    ViewBag.Title = "Index";
}

<h2>Index</h2>

<p>
    @Html.ActionLink("Create New", "Create")
</p>
<table>
    <tr>
        <th>
            @Html.DisplayNameFor(model => model.Item1[0].ProductName)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Item1[0].Supplier.CompanyName)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Item1[0].Category.CategoryName)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Item1[0].QuantityPerUnit)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Item1[0].UnitPrice)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Item1[0].UnitsInStock)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Item1[0].UnitsOnOrder)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Item1[0].ReorderLevel)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Item1[0].Discontinued)
        </th>
        <th></th>
    </tr>

@foreach (var item in Model.Item1) {
    <tr>
        <td>
            @Html.DisplayFor(modelItem => item.ProductName)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Supplier.CompanyName)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Category.CategoryName)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.QuantityPerUnit)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.UnitPrice)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.UnitsInStock)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.UnitsOnOrder)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.ReorderLevel)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Discontinued)
        </td>
        <td>
            @Html.ActionLink("Edit", "Edit", new { id=item.ProductID }) |
            @Html.ActionLink("Details", "Details", new { id=item.ProductID }) |
            @Html.ActionLink("Delete", "Delete", new { id=item.ProductID })
        </td>
    </tr>
}

</table>

<div>
    Page @(Model.Item1.PageCount < Model.Item1.PageNumber ? 0 : Model.Item1.PageNumber) of @Model.Item1.PageCount
    @if (Model.Item1.HasPreviousPage)
    {
        @Html.ActionLink("<<", "Index", new { page = 1})
        @Html.Raw(" ");
        @Html.ActionLink("< Prev", "Index", new {page = Model.Item1.PageNumber - 1})
    }
    else{
     @:<<
     @Html.Raw(" ");
        @:< Prev   
    }

    @if (Model.Item1.HasNextPage)
    {
        @Html.ActionLink("Next >", "Index", new {page = Model.Item1.PageNumber + 1})
        @Html.Raw(" "); 
        @Html.ActionLink(">>", "Index", new {page = Model.Item1.PageCount})
    }
    else{
     @:Next >
     @Html.Raw(" ")
@:>>   
    }
</div>

@foreach (var item in Model.Item2)
{
    @Html.Partial("_Orders")
}

这是我要求的控制器代码：

var q = (from o in db.Order_Details
                     where o.ProductID == id
                     join ord in db.Orders
                     on o.OrderID equals ord.OrderID
                     orderby o.Quantity descending
                     select ord);
            var qm = q.Take(3);
            return PartialView("_Orders", qm.ToList());

Answer 1

本质上，您只是想将多个模型传递给您的视图。由于您只能将一种类型传递给视图，因此做您想做的事情的方法是将模型包装在视图模型中并将其传递给您的视图。比如：

public class ProductViewModel
{
    public IPagedList<Product> Products { get; set; }
    public IEnumerable<Order> Orders { get; set; }
}

public ActionResult Index()
{
    var model = new ProductViewModel();
    model.Products = // ... fetch from database
    model.Orders = // ... fetch from database

    return View(model);
}

视图现在可以强类型化到视图模型：

@model ProductViewModel