Object reference not set to an instance of an object.

[primagic]

When a user logins to my application I am creating a session variable called 'User'. The user logins with their DXNumber)

Session("User") = txtDXNumber.Text

I am then using this session as part of a datasource as below:

<asp:sqldatasource runat="server" id="GetUserID" 
    ConnectionString="<%$ ConnectionStrings:FileawaySQLConnectionString %>" 
    SelectCommand="SELECT [BusinessID] FROM [Businesses] WHERE ([DXNumber] = @DXNumber)">
    <SelectParameters>
        <asp:SessionParameter Name="DXNumber" SessionField="User" Type="String" />
    </SelectParameters>
</asp:sqldatasource>

When I get the corresponding BusinessID, I populate a hidden label with the value

Dim dvUserID As Data.DataView = GetUserID.Select(DataSourceSelectArguments.Empty)
        Me.lblUserID.Text = dvUserID.ToTable.Rows(0)("BusinessID")

Then I link my data to the value in the label.

I am assuming that when the session expires then the value in the lblUserID is NULL which is giving me the Object reference error.

I obviously dont want to leave the session open indefinately but is there any code I can add that checks if its NULL then requery the value again or something?

 

[jbenson001]

This is only one of the many reasons that I don't like the DataSourceControls. If you write the code yourself, you can do a check for the Session var first, then run your code accordingly. You can see if the control has some sort of way to check, but I doubt it. My suggestion, write the data access code yourself.

 

[primagic]

what do you mean write the code? write the code to create the session? i am not sure where I would begin. any suggestions?

thanks

 

[jbenson001]

No, what I mean is to write the data access code yourself, and NOT use the data source controls.