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Editorial Team
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Asked: 2026-06-10T04:28:33+00:00

I use GridView & Repeater (and other like DropDownList ) controls extensively in my

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I use GridView & Repeater (and other like DropDownList) controls extensively in my application along with ObjectDataSource components and classes that serve data for ObjectDataSource (TypeName / SelectMethod attributes on ObjectDataSource). I recently noticed that SelectMethod is only called when

IsPostBack == false

Also, when I bind manually, I always bind when !IsPostBack. I never was curious how controls maintain their data between postbacks, until now (I have to create GridView with sorting/pagination etc and I want to do it efficently).

Could you explain / provide some links with descriptions how it’s done?

Also I don’t get one thing: when working with GridView and I iterate over rows, sometimes I need to access its GridViewRow.DataItem property in order to get backing object (usually to get some kind of ID). And sometimes it’s null – sometimes not. I couldn’t figure out why. However then it’s null, I still can access (for instance) GridViewRow.DataKeys.

Thanks

EDIT: know when answers say that it thanks to ViewState, I have another question: If I data bind 100 business objects which are pretty heavy and I only use a few properties while data binding (let’s say I also use OnRowDataBound event to render some additional data), does it mean that whole objects are serialized?

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1 Answer

  1. Editorial Team

    They store it in a hidden field on the page called ViewState (or more precisely “__VIEWSTATE”). If you do a View Source on your ASPX page, you’ll see it.

    You too can store and retrieve state information for your page in the ViewState by accessing the ViewState property of your Page.

    I’d start here http://msdn.microsoft.com/en-us/library/ms972976.aspx

    So, yes, if you store a large number of large objects, there is a large amount of data being transferred to and fro to the client in the page cycle. Used carefully, Viewstate can be useful, but used carelessly, it can have negative effects.

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