无法在剃刀视图中使用LINQ方法ASP.Net

Question

我在view.cshtml中这样调用模型：

@model IEnumerable<Spiirit_Project.Models.Deliverable>

然后我在view.cshtml中使用这种LINQ方法：

@{ var a = Model.Where(p => p.deliverable_research_year_id == 169).Count(); }

运行项目时，出现错误： “值不能为空。 参数名称：source”。

我的“可交付成果”表不为空，但出现此错误。如何解决此错误？

有我的控制器：

public ActionResult CreateDeliverable(int? idResearch, int? idBaseline, int? idYear){
ViewBag.IdResearch = idResearch;
ViewBag.IdBaseline = idBaseline;
ViewBag.IdYear = idYear;
ViewBag.Year = db.Deliverable_Research_Years.Find(idYear);
ViewBag.Deliverable = db.Deliverables.ToList();

return View();
}

Answer 1

@mjwills在评论中告诉我，以将模型传递给视图。所以我这样更改控制器：

public ActionResult CreateDeliverable(int? idResearch, int? idBaseline, int? idYear){
ViewBag.IdResearch = idResearch;
ViewBag.IdBaseline = idBaseline;
ViewBag.IdYear = idYear;
ViewBag.Year = db.Deliverable_Research_Years.Find(idYear);

return View(db.Deliverables.ToList());
}

这正常工作！

Answer 2

尝试

@{ var a = Model?.Where(p => p.deliverable_research_year_id == 169).Count() ?? 0; }

这是假设deliverable_research_year_id不是可为空的类型。