Inserting, updating, etc. for ListView with a custom data source
in [ASP .NET]
|
From: Harlan Messinger on 3 Apr 2010 14:44 Mr. Arnold wrote: > Harlan Messinger wrote: >> Harlan Messinger wrote: >>> In ASP.NET 3.5: Suppose I have a ListView whose data source (using >>> LINQ-to-SQL) is set with an expression for a DataSource instead of a >>> control assigned to the ListView's DataSourceId field: >>> >>> DataSource='<%#((IEnumerable<Bid>) Eval("Bids")).OrderBy(bid => >>> bid.BidDateTime)%>' >>> >>> This ListView is nested inside another one that shows information for >>> an Item in my Item table, and exposes Item.Bids, the related rows >>> from the Bid table. (This is for an auction.) >>> >>> Since I'm not using a LinqDataSource for this ListView, I don't have >>> any built-in functionality for insertion, updating, deletion, and I >>> can't seem to find out just how to do that. Any guidance, please? >> >> I've tried this, where a user has entered a bid: >> >> ListView lv = (ListView)sender; >> decimal bidPrice = >> decimal.Parse(((TextBox)lv.InsertItem.FindControl("txtBidCount")).Text); >> >> //Insert validation code here. >> >> Bid bid = new Bid(); >> bid.ItemId = ???; >> bid.ParticipantId = Session["userParticipantId"]; >> bid.BidPrice = bidPrice; >> bid.BidDateTime = DateTime.Now; >> bid.IsOnlineBid = true; >> >> AuctionData data = new AuctionData(); >> data.Bids.InsertOnSubmit(bid); >> data.SubmitChanges(); >> >> >> But I don't know what my source should be for the itemId with which >> this Bid should be associated. It's the same as the ItemId of the >> current item in the outer ListView, but I don't know how to get at >> that from within the inner ListView. I thought it might have something >> to do with inspecting lv.DataSource, but that actually seems to be >> null at this point, according to the Locals window. > > Wouldn't just use a asp:HiddenField that's global to the page? The > outter Listview would save itemid to the HF, and then Listview inner > would get the value from the HF. There's a thought. Even with the experience I *have* had with ASP.NET, I keep forgetting that the entire page is a single form and all the controls are available. On the other hand, there are the usual security provisos persisting data that way--vulnerable to monkeying around on the client side. > > And I don't see how you're going to use a datasource that belongs to > another control. As it happens, I've solved that problem: ListView lv = (ListView)sender; int itemId = (int) ((ListView)lv.NamingContainer.NamingContainer) .SelectedPersistedDataKey.Value; The first NamingContainer call gets me the placeholder from the LayoutTemplate; the second gets me the parent ListView. > > The ObjectContext is there for the Linq-2-SQL from a codebehind file > standpoint, which you may have to go to the codebehind file and manually > do the CURD for the other control. > OK, I'll take a look at that. I hadn't come across ObjectContext. So, actually, the above solved my problem, and I'm left with just one more. After extracting and validating values, I create a new Bid object containing those values, and I insert it into the table: data.Bids.InsertOnSubmit(bid); data.SubmitChanges(); But then, what ought to happen next is that the page should be redrawn, with the newly added row appearing under the previous rows in my ListView, and I'd like to see a message, "your bid has been placed". Or, if there's an error (because nonnumeric characters were entered for the amount bid, or the amount bid is lower than the previous bid), I'd also like the page to redisplay as is but with an error message. What actually happens, upon correct entry, is that the page is redrawn looking as it was before I pressed the Insert button. But when I then GET the page again, my new bid is displayed as an existing row along with the previous ones. I'm guessing I need to create an OnItemInserted handler that redirects, but then I'm not sure how to handle the success or error message. |