SessionParameter DefaultValue DBNull

Posted on 2007-11-13
Last Modified: 2008-02-01
Hi there,

This may seem like an easy question but I can't seem to get it to work. I've got a SessionParameter in a SqlDataSource with a SelectCommandType of StoredProcedure. If the SessionParameter is null/nothing I need to pass the stored procedure a value of System.DBNull.Value. How do I do that?

Question by:CoconutTelegraph
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Author Comment

ID: 20277200
btw, I've tried this but it doesn't seem to work....

<asp:SessionParameter Name="ProductID" DefaultValue="" ConvertEmptyStringToNull="true" SessionField="MySessionProductID" />
LVL 27

Accepted Solution

Sammy earned 500 total points
ID: 20277515
You need to handle the onSelecting event of the SqlDataSource
<asp:SessionParameter Name="ProductID" DefaultValue=""ConvertEmptyStringToNull="true" SessionField="MySessionProductID" Type="String"  />
protected void SqlDataSource1_Selecting(object sender, SqlDataSourceSelectingEventArgs e)
        if (e.Command.Parameters["@ProductID"].Value==null)
            e.Command.Parameters["@ProductID"].Value = DBNull.Value;

that should take care of it

Author Comment

ID: 20277559
Interesting. Can I ask you from a design perspective, which do you think is cleaner and better code?

1) Using the method you've suggested for setting the values to DBNull.Value when null.

2) Ditching the SqlDataSource, and opting to hit the database directly in the DataBinding event of the GridView and then attaching the returned ADO.Net DataTable to the DataSource property.

Hmmm. I can't decide now. :(

Anyhow thanks!!
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LVL 27

Expert Comment

ID: 20277727
I a not a fan of the SQLDataSource for a simple reason. It mixes data layer login with the UI layer
If you really have to use a control like the SqlDataSource, I would recommend using the ObjectDataSource.
take a look at the docs here

good luck

Author Comment

ID: 20277738
Good point. Well that certainly gives me something to think about. Thanks for the quick and thorough response Sammy!

LVL 27

Expert Comment

ID: 20277790
You welcome and thanks for the Points

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