C# 实体框架查询错误
为什么这样做有效:C# 实体框架查询错误,c#,entity-framework,C#,Entity Framework,为什么这样做有效: List<Item> items = ndb.Items.Where(m => m.ProductId == id).OrderByDescending(m => m.Id).ToList(); int itemid = items[0].Id; bool wlexists = ndb.Wishlists.Any(m => m.ItemId == itemid && m.UserEmail == User.Identity.Nam
List<Item> items = ndb.Items.Where(m => m.ProductId == id).OrderByDescending(m => m.Id).ToList();
int itemid = items[0].Id;
bool wlexists = ndb.Wishlists.Any(m => m.ItemId == itemid && m.UserEmail == User.Identity.Name);
List items=ndb.items.Where(m=>m.ProductId==id).OrderByDescending(m=>m.id).ToList();
int itemid=items[0].Id;
bool wlexists=ndb.Wishlists.Any(m=>m.ItemId==ItemId&&m.UserEmail==User.Identity.Name);
但这并不是:
List<Item> items = ndb.Items.Where(m => m.ProductId == id).OrderByDescending(m => m.Id).ToList();
bool wlexists = ndb.Wishlists.Any(m => m.ItemId == items[0].Id && m.UserEmail == User.Identity.Name);
List items=ndb.items.Where(m=>m.ProductId==id).OrderByDescending(m=>m.id).ToList();
bool wlexists=ndb.Wishlists.Any(m=>m.ItemId==items[0].Id&&m.UserEmail==User.Identity.Name);
如果项
具有值,即不为空,则它必须工作。你得到了什么错误
像这样做
List items=ndb.items.Where(m=>m.ProductId==id).OrderByDescending(m=>m.id).ToList();
如果(项!=null)
bool wlexists=ndb.Wishlists.Any(m=>m.ItemId==items[0].Id&&m.UserEmail==User.Identity.Name);
我看不出第二个查询不起作用的原因,您得到的异常是什么?