Check if datagridview check box is checked

Question

Hi Guys I have a datagidview where the first column is a checkbox column. Then a user can check selected rows click a button and delete those selected rows this bit works fine. My problem is that it throws an error if no check boxes are checked. How can I edit my code below to loop through datagrid first and throw message if no boxes are checked? My code below: DialogResult yourAnswer = MessageBox.Show(Are you sure you want to delete the selected items? Caption MessageBoxButtons.YesNo MessageBoxIcon.Question); if (yourAnswer == DialogResult.Yes) { for (int i = supplyDataGridView.Rows.Count - 1; i >= 0; i--) { object temp = supplyDataGridView.Rows[i].Cells[0].Value; if (!Convert.IsDBNull(temp) && Convert.ToBoolean(temp)) { supplyDataGridView.Rows.RemoveAt(i); } } } else { }

mike Delvotti · Answer

Yes - it was exactly that :-)

Vulpes · Answer

Glad to hear you've sorted it now Mike :) Was it something to do with the change not been committed when you checked a single row and then clicked the delete button as i was working on that theory when your latest post came in?

mike Delvotti · Answer

I managed to sort this it was something wierd with my datagrid the code worked after all Thank you Vulpes for sorting the null error issue :-)

mike Delvotti · Answer

No I removed that bit and still only removes two or more? Could it be something to do with the datagrid itself do you think?

Vulpes · Answer

Did it work properly before you put in the 'temp != null' bit or has it always been like this?

mike Delvotti · Answer

Whoops that was the wrong code snipet below is the one which still only lets me remove 2 or more rows? If i click two rows they remove but if I click one row it doesn't? for (int i = supplyDataGridView.Rows.Count - 1; i >= 0; i--) { object temp = supplyDataGridView.Rows[i].Cells[0].Value; if (!Convert.IsDBNull(temp) && temp != null && Convert.ToBoolean(temp)) { supplyDataGridView.Rows.RemoveAt(i); } }

Vulpes · Answer

Shouldn't this line: object temp = supplyDataGridView.Rows[i].Cells[1].Value; be this: object temp = supplyDataGridView.Rows[i]. Cells[0]. Value;

mike Delvotti · Answer

That's great thank you Vulpes. I don't know if you could help on a little strange issue? For some reason I can only remove more than one row at a time? Example If I tick 2 or 3 or 5 rows and click delete they remove fine however if I only want to remove 1 row and check 1 row it doesn't remove the row? Almost like it only works if theres 2 or more rows checked? Could it be a problem with the below code snipet?: for (int i = supplyDataGridView.Rows.Count - 1; i >= 0; i--) { object temp = supplyDataGridView.Rows[i].Cells[1].Value; if (!Convert.IsDBNull(temp) && Convert.ToBoolean(temp)) { supplyDataGridView.Rows.RemoveAt(i); } }

Vulpes · Answer

It looks like the Value property is null for all rows before any row is selected and then becomes true (if row selected) or false (if row not selected). So I'd try: bool noRowsSelected = true; for (int i = supplyDataGridView.Rows.Count - 1; i >= 0; i--) { object temp = supplyDataGridView.Rows[i].Cells[0].Value; if (temp != null) { noRowSelected = false; break; } } if (noRowSelected) { Messagebox.Show(You must select one or more rows); } else { // what you had to start with }

mike Delvotti · Answer

Hi Vulpes Yes your amendment works a treat and doesn't throw error it must of been the handling the null? So on another note how could I show a message if the user clicks delete but hasn't selected any items? something like: messagebox.show(You must select one or more rows);

Vulpes · Answer

I'm struggling to understand why there should be an error if no checkboxes are checked unless possibly you're using the ternary rather than the binary mode. Is there still an error if you change the code to this: for (int i = supplyDataGridView.Rows.Count - 1; i >= 0; i--) { object temp = supplyDataGridView.Rows[i].Cells[0].Value; if (!Convert.IsDBNull(temp) && temp != null && Convert.ToBoolean(temp)) { supplyDataGridView.Rows.RemoveAt(i); } } If so what is the error?