c# - working - where is view state stored in asp net

How to get the value of built, encoded ViewState? (2)

I need to grab the base64-encoded representation of the ViewState. Obviously this would not be available until fairly late in the request lifecycle, which is OK.

For example, if the output of the page includes:

<input type="hidden" name="__VIEWSTATE" 
  id="__VIEWSTATE" value="/wEPDwUJODU0Njc5MD...==" />

I need a way on the server side to get the value "/wEPDwUJODU0Njc5MD...=="

To clarify, I need this value when the page is being rendered, not on PostBack. e.g. I need to know the ViewState value that is being sent to the client, not the ViewState I'm getting back from them.

I enabled compression following similar articles to those posted above. The key to accessing the ViewState before the application sends it was overriding this method;

protected override void SavePageStateToPersistenceMedium(object viewState)

You can call the base method within this override and then add whatever additional logic you require to handle the ViewState.