不知道为什么我的查询将返回一个空 [英] dont get why my query is returning a null

问题描述

我的问题是有关当我想删除一个项目掀起了订单，

我只是不明白为什么它返回一个空值，它应该只是删除的项目。

 保护无效gvRevOrder_RowDeleting（对象发件人，GridViewDeleteEventArgs E）
{
    Int64的ID =新的Int64（）;
    ID =（Int64的）e.Keys [产品ID];

    使用（DatabaseCourseWorkEntities上下文=新DatabaseCourseWorkEntities（））
    {
        CWInvoiceItem项目=（由对在context.CWInvoiceItems
                              其中，p.ProductID == ID
                              选择P）.SingleOrDefault（）;

        context.CWInvoiceItems.DeleteObject（项目）;
        context.SaveChanges（）;
    }
 

下面我把事情我试图删除，正如你所看到的ProductID = 38和可变标识也有38任何想法的链接？

我已经试过各种如FirsOrDefault和这样的。

解决方案

1. 检查 context.CWInvoiceItems 中包含任何数据
2. 检查方面指向正确的数据源

My problem is related to when I want to Delete a Item off a Order,

I just dont get why it is returning a null value it should just delete the item.

protected void gvRevOrder_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
    Int64 ID = new Int64();
    ID = (Int64)e.Keys["ProductID"];

    using (DatabaseCourseWorkEntities  context = new DatabaseCourseWorkEntities())
    {
        CWInvoiceItem item = (from p in context.CWInvoiceItems 
                              where p.ProductID == ID 
                              select p).SingleOrDefault();

        context.CWInvoiceItems.DeleteObject(item);
        context.SaveChanges();
    }

below i have put a link of the thing i am trying to delete and as you can see the ProductID = 38 and the Variable ID also has 38 any ideas?

I've tried all sorts such as FirsOrDefault and such.

解决方案

1. Check that context.CWInvoiceItems contains ANY data
2. Check that the context points to the correct data source

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