GridView RowDataBound doesn't fire on postback

Question

On an ASP.NET page, I have a GridView populated with the results of a LINQ query. I'm setting the DataSource in code, then calling DataBind on it. In the GridView's RowDataBound event, I'm selectively hiding links in some GridView fields based on the query results. (For instance, I hide the "Show Parent" link of the row in question has no parent row.)

This works fine initially. But on postback (when I don't call DataBind, but the GridView stays populated through ViewState), the data displays, but the RowDataBound event (obviously) doesn't fire, and my links don't get hidden.

What's the best way to get the links to be hidden after a postback?

Solution 1

Here's how I ended up solving this:

1. I created a serializable class with readonly properties: PK of a row, and a boolean for each link indicating whether it's enabled or not. We'll call it LinkVisibility.
2. I created a serializable class inheriting from KeyedCollection to hold instances of the class above.
3. I created a ViewState-backed property holding an instance of that collection.
4. In my Search procedure (populating the GridView), I clear the collection.
5. In RowDataBound, which initially shows/hides the links, I add a LinkVisibility instance to the collection for each row.
6. In Page.Load, when IsPostBack is true, I loop through the GridView rows. I look up the LinkVisibility for each one by PK in the collection (DataKeyNames is set in the GridView), and I set the links accordingly.

I don't know that this is the best way to do this, but it certainly does work, which is more than I can say for anything else I've tried.

Solution 2

The RowDataBound event only fires when the GridView's data changes during the postback. The event is short-circuited for speed so it's not re-generating the exact same data unnecessarily. Use the RowCreated event to manipulate the HTML instead - it fires on every postback regardless of whether the data has changed.

Solution 3

1) You could have a Method - ProcessDataRows() that would get called once on grid_DataBound(...). And then when you need it after PostBack.

And that way you process all rows when you want.

2) You could have methods like ShowParentLink(). That are then bound to the LinkButton in the grid (if you're using an ItemTemplate) and the link would have

Visible='<%#ShowParentLink()%>'

Comments

[ForceMagic]

Welcome on SO, here, it is a good practice to explain why to use your solution and not just how. That will make your answer more valuable and help further reader to have a better understanding of how you do it. I also suggest that you have a look on our FAQ : stackoverflow.com/faq.

[dlchambers]

But, sadly, e.Row.DataItem is null on RowCreated whereas it's non-null on RowDataBound :(