我正在使用Visual Studio 2013 Update 2,我在我的一个控制器中遇到了未处理的异常,我无法确定它来自何处。 这是控制器:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Threading.Tasks;
using System.Web;
using System.Web.Mvc;
using System.Data.Entity;
using Microsoft.AspNet.Identity;
namespace SophicCeramics.Controllers
{
public class ShopController : BaseController
{
public ActionResult Cart()
{
var order = FindOrCreateOrder();
var m = new Models.Order.Cart(); //
m.Date = order.OrderDate;
m.Total = order.OrderLineItems.Sum(i => i.Quantity * i.UnitPrice);
m.ItemCount = order.OrderLineItems.Count;
m.Items = order.OrderLineItems.ToList();
return View(m);
}
public async Task<ActionResult> AddItem(int productId)
{
var product = _context.Products.FirstOrDefault(p => p.ProductId == productId);
var order = FindOrCreateOrder();
var item = order.OrderLineItems.FirstOrDefault(i => i.ProductId == productId);
if (item != null)
{
item.Quantity++;
await _context.SaveChangesAsync();
}
else
{
item = new OrderLineItem();
item.OrderHeader = order;
item.Product = product;
item.Quantity = 1;
item.UnitPrice = product.Price;
order.OrderLineItems.Add(item);
await _context.SaveChangesAsync();
}
return RedirectToAction("Cart");
}
private OrderHeader FindOrCreateOrder()
{
var UserName = this.User.Identity.Name;
var user = UserManager.FindByName(UserName);
var customer = _context.Customers
.Include(c => c.OrderHeaders.Select(o => o.OrderLineItems.Select(i => i.Product))).
FirstOrDefault(c => c.UserId.Equals(user.Id));
var order = customer.OrderHeaders
.OrderBy(o => o.OrderDate)
.LastOrDefault(o => o.Paid == false);
if(order == null)
{
order = new OrderHeader();
//var Customer = new Customer();
order.Customer = customer;
customer.OrderHeaders.Add(order);
_context.SaveChanges();
}
return order;
}
}
}
这是视图模型:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
namespace SophicCeramics.Models.Order
{
public class Cart
{
public int ItemCount { get; set; }
public DateTime Date { get; set; }
public decimal Total { get; set; }
public List<OrderLineItem> Items { get; set; }
public decimal UnitPrice { get; set; }
public int OrderHeaderId { get; set; }
public string CustomerId { get; set; }
public System.DateTime OrderDate { get; set; }
public bool Paid { get; set; }
public int OrderLineItemId { get; set; }
public int ProductId { get; set; }
public int Quantity { get; set; }
public int CategoryId { get; set; }
public int ArtistId { get; set; }
public string Title { get; set; }
public decimal Price { get; set; }
public string ProductArtUrl { get; set; }
public string ProductArtMain { get; set; }
public string UserId { get; set; }
public string Firstname { get; set; }
public string Lastname { get; set; }
}
}
这就是观点:
@model SophicCeramics.Product
@{ ViewBag.Title = "Cart"; }
<div>
<h4>Product</h4>
<hr />
<dl class="dl-horizontal">
<dt>
@Html.DisplayNameFor(model => model.Title)
</dt>
<dd>
@Html.DisplayFor(model => model.Title)
</dd>
<dt>
@Html.DisplayNameFor(model => model.Price)
</dt>
<dd>
@Html.DisplayFor(model => model.Price)
</dd>
<dt>
@Html.DisplayNameFor(model => model.ProductArtUrl)
</dt>
<dd>
@Html.DisplayFor(model => model.ProductArtUrl)
</dd>
<dt>
@Html.DisplayNameFor(model => model.ProductArtMain)
</dt>
<dd>
@Html.DisplayFor(model => model.ProductArtMain)
</dd>
<dt>
@Html.DisplayNameFor(model => model.Artist.Name)
</dt>
<dd>
@Html.DisplayFor(model => model.Artist.Name)
</dd>
<dt>
@Html.DisplayNameFor(model => model.Category.Name)
</dt>
<dd>
@Html.DisplayFor(model => model.Category.Name)
</dd>
</dl>
</div>
<p>
@Html.ActionLink("Edit", "Edit", new { id = Model.ProductId }) |
@Html.ActionLink("Back to List", "Index")
</p>
View具有自动布局页面。 我不断收到指向这行代码的错误:
var customer = _context.Customers
.Include(c => c.OrderHeaders.Select(o => o.OrderLineItems.Select(i => i.Product))).
FirstOrDefault(c => c.UserId.Equals(user.Id));
无论我如何重新排列include语句,它都无法正常工作。 此外,控制器继承自另一个名为BaseController的控制器,该控制器通过_context连接到数据库。 我也尝试过添加edmx中.tt文件中相关类的所有内容,但仍然会出错。 此外,当我在客户变量上设置断点并逐步执行它时,它会直接转到BaseController中的dispose方法。
答案 0 :(得分:0)
我猜测user
为空,所以在这里访问lambda表达式中的user.Id
时会出现错误
var customer = _context.Customers
.Include(c => c.OrderHeaders.Select(o => o.OrderLineItems
.Select(i => i.Product)))
.FirstOrDefault(c => c.UserId.Equals(user.Id));
您需要检查此行后user
是否为空
var user = UserManager.FindByName(UserName);
并且仅在FindOrCreateOrder
非空时才执行user
方法内的其余代码。如果user
块中的else
为空,您还需要决定该怎么做,如下所示
private OrderHeader FindOrCreateOrder()
{
var UserName = this.User.Identity.Name;
var user = UserManager.FindByName(UserName);
if (user != null)
{
var customer = _context.Customers
.Include(c => c.OrderHeaders.Select(o => o.OrderLineItems.Select(i => i.Product))).
FirstOrDefault(c => c.UserId.Equals(user.Id));
var order = customer.OrderHeaders
.OrderBy(o => o.OrderDate)
.LastOrDefault(o => o.Paid == false);
if(order == null)
{
order = new OrderHeader();
//var Customer = new Customer();
order.Customer = customer;
customer.OrderHeaders.Add(order);
_context.SaveChanges();
}
return order;
}
else
{
// logic when user is null
}
}