Datetime = null?

[samsmithnz]

I'm trying to add a row to my dataset programattically, but I can't seem to add a null value to a datetime in the row.

 

objDR = dsReviewers.Tables("Reviewers").NewRow
objDR.Item("reviewer_notification_date") = nothing

 

I thought that was the equivalent, but it doesn't work, if I isdbnull it further down the page, I get this error:

System.ArgumentException: Cannot set Column 'reviewer_notification_date' to be null. Please use DBNull instead. at System.Data.DataRow.set_Item(DataColumn column, Object value) at System.Data.DataRow.set_Item(String columnName, Object value) at APWorkflow.Reviewers.btnAdd_Click(Object sender, ImageClickEventArgs e) in \\corpdev1\wwwroot$\APWorkflow\Reviewers.aspx.vb:line 159 

 

what am I doing wrong, It seems like I've already tryed everything!@@!@

[Aitmanga]

You could try:

 

objDR.Item("reviewer_notification_date")=System.DBNull.Value

[samsmithnz]

That seemed to work, but then later when I saved the dataset to the viewstate and reloaded it, the column with the null value was dropped off. Any other suggestions...?

[Nerseus]

Do you mean you saved the DataSet as XML and reloaded it? Make sure you specifiy to save the schema. DBNull values are represented in XML by NOT being there :)

 

-Nerseus

[samsmithnz]

Yeh I've just been experimenting with that. I think I know a bit more of the problem (but its still a problem). What I'm trying to do is do an initial read from the database, and read my dataset up to my asp.net page where its bound to a datagrid. I then save the dataset away in the viewstate, and retrieve it whenever I have to add or delete a row. When the user presses the save button it goes back to the database. This all works fine until I read from the database and there are NO rows.

objDataRow = dsReviewers.Tables("Reviewers").NewRow

This fails as it doesn't know what the schema was. So I added these lines to the database call:

'Fill the dataset from the dataadapter
objDataSet = New DataSet
objDataSet.Tables.Add("Reviewers")
objSQLDA.FillSchema(objDataSet.Tables("Reviewers"), SchemaType.Mapped)
objSQLDA.Fill(objDataSet, "Reviewers")

Now I create the table and populate if I need too + I'm getting the schema, so now it should know what sort of row to add when I call NewRow right? Well not yet. What happens is when I step through the code it all looks right until I save it to my viewstate. When I read it out, my empty table is GONE!

 

What's wrong?

[samsmithnz]

*Bump* I'm sorry I hate doing this, but its friday and deadlines are upon me! :eek: :eek: :eek: