How to override toolStripButton in bindingNavigator?

Hey Experts,
i have a binding source and binding Navigator that have a toolStripButton (standard) that addes a new item to a datagridview.
My problem is if i click on this toolStripButton 2 times, then i get i NoNullAllowedException Unhandled.
How can i handel that?
PS.: My datagridview has only one column. in this column is PK and NOT NULL
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Jaime OlivaresSoftware ArchitectCommented:
in your toolStripButton event (method), check for nullity before any operation. if null just return silently.
delmandiyarAuthor Commented:
Hey jaime_olivares

Thank you for quick replay.
Check for nullity befor any operation!! There are not any events that checkes for nullity. How can i do that?
delmandiyarAuthor Commented:
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Bob LearnedCommented:
If you have a data source, and a DataGridView, you can bind the data source directly to the DataGridView, and be able to add, edit, and delete rows.
delmandiyarAuthor Commented:
But i need this binding navigator.
Bob LearnedCommented:
First, I am curious why you "need"?  Second, it looks like you already have a solution from the link that you posted, so what help do you need?
delmandiyarAuthor Commented:
first: because the application is for people that need this binding navigator
Second: the solution from the link is just a walk around the problem.
And the walk around is not working for me too.
Bob LearnedCommented:
I don't see any problem with the DefaultValuesNeeded event handler approach:

private void dataGridView1_DefaultValuesNeeded(object sender, DataGridViewRowEventArgs e)
    e.Row.Cells["Country"].Value = "USA";
    e.Row.Cells["CustomerID"].Value = NewCustomerId();
delmandiyarAuthor Commented:
There are not any default values!!
So how could i use DefaultValuesNeeded event?? and my table that my datagridview is bounded with, contains only one column.
Bob LearnedCommented:
Defining default values when you add rows should keep the DataGridView from complaining about null value.

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delmandiyarAuthor Commented:
I did not solve the problem, but i got a walk around tip.
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