DataGridView和BindingList：如何检查单元格值是否已更改？

Question

I've got datagridview with DataSource set to myBindingList. Items of list implement INotifyPropertyChanged so datagridview automatically responds to changes in the list.

Now I have to calculate some summaries of datagridview columns.

It should be done when:

• datasource changes(OnDataSourceChanged)
• cell value changes(OnCellValueChanged)

First one is clear, but I've got a small problem with the second one.

OnCellValueChanged fires when the user changes value of cell by control or on:

myDataGridView.Rows[x].Cells[y].Value=newValue;

but what about:

myBindingList[myInvoice].Property1=newValue;

DataGridView automatically refreshes (INotifyPropertyChanged) but it doesn't fire OnCellValueChanged event.

Any idea how can I get such info from my DataGridView? It has to be done on DataGridView level because I'm writing my own control which extends dgv.

Thanks for the help.

Answer 1

This closest I can think of to solves this is to use a BindingSource as the datasource and then within your custom DataGridView raise your own event in response to the BindingSource ListChanged event.

I'd probably override OnDataSourceChanged something like this:

public event EventHandler CustomCellValueChanged;

protected override void OnDataSourceChanged(EventArgs e)
{
    bs = this.DataSource as BindingSource;

    if (bs == null)
    {
        throw new ArgumentException("DataSource must be a BindingSource");
    }

    bs.ListChanged += new System.ComponentModel.ListChangedEventHandler(bs_ListChanged);

    base.OnDataSourceChanged(e);
}

void bs_ListChanged(object sender, System.ComponentModel.ListChangedEventArgs e)
{            
    if (CustomCellValueChanged != null)
    {               
        CustomCellValueChanged(this, new EventArgs());
    }
}

The problem with this is that there is no way (I can think of) to get the correct cell properties so you would have to reevaluate all the columns, not just the column that contained the change.