我遇到了RenderAction的一个奇怪问题。由于我的视图模型非常复杂，我将尝试按照以下步骤简化流程：
似乎唯一的区别是，填充大视图模型的主控制器操作（不是部分）最初是通过get获得的，然后通过帖子到达时失败。我用模型玩了好几个小时 - 甚至从头开始重新创建模型 - 所以它与模型无关。
这是堆栈跟踪：
at System.Web.HttpServerUtility.ExecuteInternal(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage, VirtualPath path, VirtualPath filePath, String physPath, Exception error, String queryStringOverride)
at System.Web.HttpServerUtility.Execute(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage)
at System.Web.HttpServerUtility.Execute(IHttpHandler handler, TextWriter writer, Boolean preserveForm)
at System.Web.HttpServerUtilityWrapper.Execute(IHttpHandler handler, TextWriter writer, Boolean preserveForm)
at System.Web.Mvc.Html.ChildActionExtensions.ActionHelper(HtmlHelper htmlHelper, String actionName, String controllerName, RouteValueDictionary routeValues, TextWriter textWriter)
at System.Web.Mvc.Html.ChildActionExtensions.RenderAction(HtmlHelper htmlHelper, String actionName, Object routeValues)
at ASP._Page_Views_Pricelist__drawProductPricelistProductRow_cshtml.Execute() in c:\Users\Administrator\Documents\ProofPix_TFS\ProofPix\ProofPixAdmin\Views\Pricelist\_drawProductPricelistProductRow.cshtml:line 35
at System.Web.WebPages.WebPageBase.ExecutePageHierarchy()
at System.Web.Mvc.WebViewPage.ExecutePageHierarchy()
at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage)
at System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance)
at System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer)
at System.Web.Mvc.HtmlHelper.RenderPartialInternal(String partialViewName, ViewDataDictionary viewData, Object model, TextWriter writer, ViewEngineCollection viewEngineCollection)
at System.Web.Mvc.Html.RenderPartialExtensions.RenderPartial(HtmlHelper htmlHelper, String partialViewName, Object model)
at ASP._Page_Views_Pricelist_edit_cshtml.Execute() in c:\Users\Administrator\Documents\ProofPix_TFS\ProofPix\ProofPixAdmin\Views\Pricelist\Edit.cshtml:line 121
at System.Web.WebPages.WebPageBase.ExecutePageHierarchy()
at System.Web.Mvc.WebViewPage.ExecutePageHierarchy()
at System.Web.WebPages.StartPage.RunPage()
at System.Web.WebPages.StartPage.ExecutePageHierarchy()
at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage)
at System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance)
at System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer)
at System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult)
at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1a.<InvokeActionResultWithFilters>b__17()
at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation)
这是renderAction：
Html.RenderAction("_pricelistProductOptions", new { id = Model.Product.ProductId, ShowHtml = false });
非常感谢您的帮助。 BTW（有点新手）！
编辑（添加行动）
// POST: /Pricelist/Edit/5
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Edit(adminEditPricelistVM adminEditPricelistVM)
{
if (ModelState.IsValid)
{
//Code removed for simplicity
return RedirectToAction("Edit", new { id = pricelist.PricelistId });
}
int vendorId = (int)adminEditPricelistVM.VendorId;
Vendor vendor = (from b in db.Vendors where b.VendorId == vendorId select b).SingleOrDefault();
adminEditPricelistVM.ProductCategories = (from a in db.ProductCategories
from b in db.VendorProductCategory
where b.VendorId == vendorId && a.ProductCategoryId == b.ProductCategoryId
select a).OrderBy(o => o.SortOrder).ToList();
List<Product> products = (from a in db.Products where a.DiscontinuedDate == null && a.VendorId == 1 select a).OrderBy(o => o.SortOrder).ToList();
//repopulate ProductCategory and Vendor nav properties in the Formula items as these are no longer populated after post
foreach(PricingFormula pf in adminEditPricelistVM.PricingFormulas){
pf.ProductCategory = (from a in adminEditPricelistVM.ProductCategories where a.ProductCategoryId == pf.ProductCategoryId select a).SingleOrDefault();
pf.Vendor = vendor;
}
adminEditPricelistVM.Pricelist.PricingFormulas = new List<PricingFormula>();
adminEditPricelistVM.Pricelist.PricingFormulas.AddRange(adminEditPricelistVM.PricingFormulas);
List<PricelistProduct> thisFilteredPP = (from a in adminEditPricelistVM.Pricelist.PricelistProducts where a.ProductId > 0 select a).ToList();
List<PricelistProductOption> thisOptionsToDelete = new List<PricelistProductOption>();
List<PricelistProductOptionsDetail> thisOptionDetailsToDelete = new List<PricelistProductOptionsDetail>();
//filter pricelistProducts so only selected options remain in list
foreach (PricelistProduct pp in thisFilteredPP)
{
pp.PricelistId = adminEditPricelistVM.Pricelist.PricelistId;
var x = pp.ProductId;
foreach (PricelistProductOption ppo in pp.PricelistProductOptions)
{
//repopulate PricelistProduct object
ppo.PricelistProduct = pp;
ppo.PricelistProductId = pp.PricelistProductId;
int numPODs = (from a in ppo.PricelistProductOptionsDetails where a.ProductOptionsDetailId > 0 select a).Count();
if (numPODs == 0)
{
thisOptionsToDelete.Add(ppo);
}
else
{
foreach (PricelistProductOptionsDetail ppod in ppo.PricelistProductOptionsDetails)
{
//repopulate PricelistProductOption object
ppod.PricelistProductOption = ppo;
ppod.PricelistProductOptionsId = ppo.PricelistProductOptionId;
if (ppod.ProductOptionsDetailId == 0)
{
thisOptionDetailsToDelete.Add(ppod);
}
else //POD is selected but if it is the default option and it is the only option and it is priced at 0.00, then we will remove it to as it is the default setting.
{
if (ppod.Price == 0 && numPODs == 1)
{
ProductOptionsDetail prodOpDet = (from c in db.ProductOptionsDetails where c.ProductOptionsDetailId == ppod.ProductOptionsDetailId select c).SingleOrDefault();
if (prodOpDet.IsDefault == true)
{
thisOptionsToDelete.Add(ppo);
}
}
}
}
foreach (PricelistProductOptionsDetail dppod in thisOptionDetailsToDelete)
{
ppo.PricelistProductOptionsDetails.Remove(dppod);
}
thisOptionDetailsToDelete.Clear();
}
}
foreach (PricelistProductOption dppo in thisOptionsToDelete)
{
pp.PricelistProductOptions.Remove(dppo);
}
thisOptionsToDelete.Clear();
}
adminEditPricelistVM.Pricelist.PricelistProducts = new List<PricelistProduct>();
adminEditPricelistVM.Pricelist.PricelistProducts.AddRange(thisFilteredPP);
adminEditPricelistVM.PPPVMs =
(from product in products
join pricelistProduct in adminEditPricelistVM.Pricelist.PricelistProducts on product.ProductId equals pricelistProduct.ProductId into gj
from subpricelistProduct in gj.DefaultIfEmpty()
select new adminEditProductsPricelistProductsVM()
{
CategoryId = (int)product.ProductCategoryId,
Product = product,
PricelistProduct = subpricelistProduct
}).ToList();
//repopulate PricelistProducts.Product and PricelistProducts.ProductCategory in Pricelist
foreach (PricelistProduct pp in adminEditPricelistVM.Pricelist.PricelistProducts)
{
pp.Product = (from p in products where p.ProductId == pp.ProductId select p).SingleOrDefault();
pp.ProductCategory = (from a in adminEditPricelistVM.ProductCategories where a.ProductCategoryId == pp.ProductCategoryId select a).SingleOrDefault();
pp.Pricelist = adminEditPricelistVM.Pricelist;
}
ViewBag.PricingFormulaRoundingTypes = (from c in db.PricingFormulaRoundingTypes select c).ToList();
var errors = ModelState.Select(x => x.Value.Errors).ToList();
return View(adminEditPricelistVM);
}
答案 0 :(得分：0)
这个答案只是一个例子，因为实际的错误没有显示，只是堆栈跟踪。
//repopulate PricelistProducts.Product and PricelistProducts.ProductCategory in Pricelist
foreach (PricelistProduct pp in adminEditPricelistVM.Pricelist.PricelistProducts)
{
pp.Product = (from p in products where p.ProductId == pp.ProductId select p).SingleOrDefault();
您的PricelistProducts可能有更多产品，ProductId与products列表中的任何产品都不匹配，导致pp.Product设置为null。
使用
为Model.PricelistProducts中的每个对象呈现操作时
html.RenderAction("_pricelistProductOptions", new { id = Model.Product.ProductId, ShowHtml = false });
它会（可能）抛出System.NullReferenceException: Object reference not set to an instance of an object.，因为您无法调用Model.Product.ProductId，因为Model.Product为空。
答案 1 :(得分：0)
你在那里使用Razor引擎（* .cshtml文件）？在这种情况下，你必须使用：
@Html.Action("actionName", "controllerName", new { id="myId" })
并且，似乎你把视图的名称放在那里“_pricelistProductOptions”，而不是动作。我怀疑你有：public ActionResult _pricelistProductOptions(....)对吗？