错误:System.Data.SqlClient.SqlException:不允许新事务，因为会话中正在运行其他线程

我正在尝试单独更新每个产品，其中多个产品可以在一个订单中找到。当我按提交/更新时，我将订单 ID 与新产品数量一起发送到控制器。这是我看到的错误：

System.Data.SqlClient.SqlException：不允许新事务 因为会话中还有其他线程在运行。

这是重定向到表单的控制器。

[HttpGet]
    [Authorize(Roles = "ADM")]
    public ActionResult UpdateDetails(Guid id)
    {
        BusinessLayer.Orders blorder = new BusinessLayer.Orders();
        return View(blorder.GetOrderDetailsByOrderId(id));
    }

这是形式。

@model IQueryable<CommonLayer.ORDERDETAIL>
@{
    ViewBag.Title = "UpdateDetails";
    Layout = "~/Views/Shared/_Layout.cshtml";
}
<h2>UpdateDetails</h2>

<table class="table table-striped" style="font-size:medium;">
    <tr>
        <th>
            Order Details ID
        </th>
        <th>
            Price
        </th>
        <th>
            VAT Rate
        </th>
        <th>
            Quantity
        </th>
    </tr>
    @foreach (var item in Model)
    {
            <tr>
                <td>
                    @Html.DisplayFor(modelItem => item.OrderDetailsId)
                </td>
                <td>
                    @Html.DisplayFor(modelItem => item.ProductPrice)
                </td>
                <td>
                    @Html.DisplayFor(modelItem => item.ProductVATRate)
                </td>
                <td>
                    <form action="/order/updatedetails/@item.OrderDetailsId" method="post" enctype="multipart/form-data">
                        <input type="text" name="prodqty" value="@item.ProductQuantity" />
                        <div class="form-group">
                            <div class="col-md-offset-2 col-md-10">
                                <br />
                                <input type="submit" value="Update" class="btn btn-primary" />
                            </div>
                        </div>
                    </form>
                </td>
            </tr>
        }
</table>

这是表单重定向到的控制器。

[HttpPost]
    [Authorize(Roles = "ADM")]
    public ActionResult UpdateDetails(Guid id, int prodqty)
    {
        BusinessLayer.Orders blorder = new BusinessLayer.Orders();
        CommonLayer.ORDERDETAIL orderdetail = blorder.GetOrderDetailByDetailId(id);
        blorder.UpdateOrderDetails(orderdetail, prodqty);
        return RedirectToAction("ViewOrder");
    }

这是用于实际更新股票的代码。

public void UpdateOrderDetails(CommonLayer.ORDERDETAIL orderdetail, int prodqty)
    {
            CommonLayer.ORDERDETAIL orderDetails = this.GetOrderDetail(orderdetail.OrderDetailsOrderId);
            CommonLayer.ORDERDETAIL od = new CommonLayer.ORDERDETAIL();
            DataLayer.DAProducts daprod = new DataLayer.DAProducts(this.Entities);
            CommonLayer.PRODUCT product = daprod.GetProduct(orderDetails.OrderDetailsProductId);
            od.OrderDetailsProductId = orderDetails.OrderDetailsProductId;
            od.OrderDetailsId = orderDetails.OrderDetailsId;
            od.OrderDetailsOrderId = orderDetails.OrderDetailsOrderId;
            od.ProductVATRate = orderDetails.ProductVATRate;
            od.ProductPrice = orderDetails.ProductPrice;
            od.ProductQuantity = prodqty;
            if (od.ProductQuantity <= product.ProductQuantity)
            {
                if (od.ProductQuantity > orderDetails.ProductQuantity)
                {
                    product.ProductQuantity -= (od.ProductQuantity - orderDetails.ProductQuantity);
                    daprod.UpdateProduct(product);
                    this.Entities.Entry(orderDetails).CurrentValues.SetValues(od);
                    this.Entities.SaveChanges();
                }
                else if (od.ProductQuantity < orderDetails.ProductQuantity)
                {
                    product.ProductQuantity += (orderDetails.ProductQuantity - od.ProductQuantity);
                    daprod.UpdateProduct(product);
                    this.Entities.Entry(orderDetails).CurrentValues.SetValues(od);
                    this.Entities.SaveChanges();
                }
            }
        else
        {
            throw new Exception("Stock is too low");
        }
    }

这就是显示错误的地方，this.Entities.SaveChanges();

public void UpdateProduct(CommonLayer.PRODUCT product)
    {
        CommonLayer.PRODUCT ExistingProduct = this.GetProduct(product.ProductId);
        this.Entities.Entry(ExistingProduct).CurrentValues.SetValues(product);
        this.Entities.SaveChanges();
    }

如何解决问题？

using(var context = new CommonLayer.DBModelEntities()){
 if (od.ProductQuantity > orderDetails.ProductQuantity)
 {
   product.ProductQuantity -= (od.ProductQuantity - orderDetails.ProductQuantity);
   daprod.UpdateProduct(product, context);
   context.Entry(orderDetails).CurrentValues.SetValues(od);
 }
 else if (od.ProductQuantity < orderDetails.ProductQuantity)
 {
    product.ProductQuantity += (orderDetails.ProductQuantity - od.ProductQuantity);
    daprod.UpdateProduct(product, context);
    context.Entry(orderDetails).CurrentValues.SetValues(od);
 }
 context.SaveChanges();
}

public void UpdateProduct(CommonLayer.PRODUCT product, CommonLayer.DBModelEntities context)
{
  CommonLayer.PRODUCT ExistingProduct = this.GetProduct(product.ProductId);
  context.Entry(ExistingProduct).CurrentValues.SetValues(product);
}

[HttpPost]
[Authorize(Roles = "ADM")]
public ActionResult UpdateDetails(Guid id, int prodqty)
{
  // Entities.BeginTransaction here;
  BusinessLayer.Orders blorder = new BusinessLayer.Orders();
  CommonLayer.ORDERDETAIL orderdetail = blorder.GetOrderDetailByDetailId(id);
  blorder.UpdateOrderDetails(orderdetail, prodqty);
  /*Now, check if your data can be Saved by triggering SaveChanges()
   if(Entities.SaveChanges)
  {
    Entities.Commit
  }else
  {
    Entities.Rollback
  } */
  return RedirectToAction("ViewOrder");
}