Adding a DataSet to the ViewState

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Hi,

I'm adding a DataSet object to the viewstate in the Page_Load().

protected void Page_Load(object sender, EventArgs e)
{
    string path = "...";
    DataSet ds = XmlOperations.GetXmlFile(path);
    ViewState["DataSet"] = ds;
    ...
}

Then at some point I need to change the contents of the DataSet, thus I have to change the DataSet and re-add the DataSet to the ViewState.

protected void btnSave_Click(object sender, EventArgs e)
{   ...
    ViewState["DataSet"] = newDataSet;
    ...
}

When I try to get the new DataSet (after the page reloads), the DataSet object that is returning is the original DataSet and not the 'newDataSet'.

Can you change a ViewState object on postback? How?
I dont want to use Session.

Posted 24-Jun-10 4:11am

rudolphgatt

Updated 24-Jun-10 4:34am

LittleYellowBird

v2

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Sandeep Mewara · Answer 1 · 2010-06-24T04:41:00

rudolphgatt wrote:
DataSet object to the viewstate

Not a good practise as DataSet's can be huge and storing them in ViewState might affect performance.

rudolphgatt wrote:
Can you change a ViewState object on postback

Yes

rudolphgatt wrote:
How?

What you have done in btnSave looks fine. ViewState will get updated as that line gets executed.

rudolphgatt wrote:
the DataSet object that is returning is the original DataSet and not the 'newDataSet'.

Looks like you missed using IsPostback property of the page.

Do something like:

C#

protected void Page_Load(object sender, EventArgs e)
{    
   string path = "...";    
   if(!IsPostback)
   {
      DataSet ds = XmlOperations.GetXmlFile(path);    
      ViewState["DataSet"] = ds;    
   }
   //...

}

Currently, the Viewstate is updated at every page load. You might just want that to happen for the first time when page loads.