Author claims ObjectDataSource is bound to data source before Page_Load and not after

carewithl · August 10th, 2009, 05:51 PM

Greetings

Iâm learning Asp.Net in parallel with reading this book, so I apologize if Iâm way off with my questions.

1) Anyways, on page 257 author says the following:

Quote:

Userâs location is not retrieved directly from her profile in the precceding code because that would cause a read for each and every row. Instead user's country, state and city are read only once from the profille and saved in local variables. Page_Load cannot be used for this because automatic binding done by the ObjectDataSource hapens earlier, so we have to use the Page_Init event handler

As far as I know ObjectDataSource is bound to data source after Page_Load and not before?! Or am I missing something?

2) Why does author ( on page 256 ) call gvwArticles.DataBind inside dllArticlesPerPage_SelectedIndexChanged, dllCategories_SelectedIndexChanged and gvwArticles_RowCommand.

As far as I know, ObjectDataSource will automatically call gvwArticles.DataBind on each postback?! I checked this by deleting gvwArticles.DataBind inside those methods, and as far as I could tell, everything worked the same! Or am I again missing something?

cheers

Lee Dumond · August 11th, 2009, 03:24 PM

Quote:

Originally Posted by carewithl

As far as I know ObjectDataSource is bound to data source after Page_Load and not before?! Or am I missing something?

You are missing something. I think you're confusing the Page_Load of a user control with the Page_Load of a page.

Don't forget, this is a user control you are dealing with. This user control will be hosted in a page.

In the host page life cycle, the ODS databinding takes place before the Page_Load of any user controls hosted in that page.

carewithl · August 13th, 2009, 02:20 PM

Quote:

Originally Posted by Lee Dumond

You are missing something. I think you're confusing the Page_Load of a user control with the Page_Load of a page.

In the host page life cycle, the ODS databinding takes place before the Page_Load of any user controls hosted in that page.

Uhm, are you sure about ODS data binding happening before Page_Load? If we add an ObjectDataSource with a Select method that returns an array of strings, a user control (.ascx) with a repeater that binds to the data source, and a page which added this user control, then the order of events is the following:

Code:

  MyObjectDataSource -> Init
UserControl -> Init
Page -> Init
Page -> Load
UserControl -> Load
MyObjectDataSource -> Load
Repeater1 -> DataBinding
MyObjectDataSource -> Selecting
MyObjectDataSource -> SelectMethod
Repeater1 -> DataBound

Thus UserControl.Load happens before MyObjectDataSource performs data binding. I’m probably (again) missing something very obvious?!

BTW - Nevermind my second question. I thought that ODS performs data binding on each postback, which apparently isn’t the case

cheers mate