BindingNavigator problems: column cannot be null

Hello Dear

there is any column which is not nullable at DB and ur entering null data in that field
Or may be u r not binding this feild with any control and u insert data it remain null

I understand that I can't enter a null, where my column is not nullable, but the exception is raised in such a way that it seems untrappable.

As an example, I can do the following in the Click event handler for the BindingNavigator's 'Save' button, like so:

    try
    {
        myBindSource.EndEdit();
        myTableAdapter.Update(myDataTable);
        MessageBox.Show("Update successful");
    }
    catch (Exception ex)
    {
        MessageBox.Show(string.Format("Update failed - {0}", ex.Message));
    }

but, it seems stupid to try:

    try
    {
        Application.Run(new myForm);
    }
    catch (Exception ex)
    {
        MessageBox.Show(string.Format("General failure - {0}", ex.Message));
    }

because, by this point, the form has already been destroyed.

Is this some kind of oversight by Microsoft in its develoment of the BindingNavigator object, or am I handling the whole thing wrong?

J.

So far, I am preventing the second click, by extending the BindingNavigator as follows:

    public class ExtendedBindingNavigator : BindingNavigator
    {
        public ExtendedBindingNavigator()
        {
            this.ItemClicked += new ToolStripItemClickedEventHandler(ExtendedBindingNavigator_ItemClicked);
        }

        private void ExtendedBindingNavigator_ItemClicked(object sender, ToolStripItemClickedEventArgs e)
        {
            if (sender == this.AddNewItem && this.BindingSource != null)
                this.BindingSource.CancelEdit();
        }
    }

Seems a bit of a hack, though...

J.

Hello Dear

This code is not giving clear understanding. Describe in detail.

Thanks, sumix, that confirms both what I thought and what I am doing.  

As such, the I feel next question is fairly obvious:  What is the best way to insert new records, when the Null constraint is fired by the dataset?  My INSERT SQL statement provides default values for certain null entries (incremented sequences, etc) and, as such, I do not want the end user to be able to edit these fields.  These fields are, therefore, databound to Labels.

I was under the impression that, when you call MyTableAdapter.Update(MyDataTable) the TableAdapter object would decide for itself whether to use the INSERT statement or the UPDATE one, dependant on whether the row already existed, but this seems not to be the case.  The UPDATE SQL is always called, which fails the null constraints (both at the dataset and at the database, when MyDataset.EnableConstraints = false)

What is the most efficient way to perform my insertion when 'Save' is clicked?

J.

When you click an a AddNew button a new row is added in the datatable and its RowState is 'Added'. When you call Update method of the tableadapter, depending on the RowState property, the corresponding Insert/Update/Delete command is executed for every row - this is true.
You should set default values for columns in the DataTable where is the case (dataTable1.Columns["column"].DefaultValue property) or you may set EnforceContraints property of the dataset to false before starting editing the table (this will stop constraints checking).
 So, in Save click you could only call Update method of the tableadapter.