Accessing CheckBox on row in Datagridview

Smith

Why on earth it's so difficult to find a sample on the web for this topic? Nobody has ever tried putting a checkbox on a datagridview on a winform? Or my search is wrong? This thread's subject has been my search key. Gettin nothin. What's wrong with the below code? DataGridViewCheckBoxCell chk = (DataGridViewCheckBoxCell)dataGridView1.Rows[0].Cells[0]; if (chk.Selected) { MessageBox.Show("Selected!"); } It's always checking the "cells" selected state. I want to know if the check box has been selected(Checked!) or not. Yes, I added column 0 to be a DataGridViewCheckBoxCell. Anybody can help?

:beer:

dan sh

The Value property would give the checked state of the cell. :) BTW, instead of casting, you can use as keyword along with the null check.

Smith

How do I access it's value? The below attempt is successfuly throwing a cast exception. if (CheckState.Checked == (CheckState)dataGridView1.Rows[0].Cells[0].Value) { MessageBox.Show("ok"); }

:beer:

Luc Pattyn

so look at dataGridView1.Rows[0].Cells[0].Value.ToString() to discover what might be wrong. everything responds well to ToString(), except null of course. :)

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dan sh

The property Value will have value as true or false. Try casting that to boolean.

Smith

Something's troubling. It requires me to "check" the checkbox at least once before checking it's VALUE to stop it from whining. If I call dataGridView1.Rows[0].Cells[0].Value.ToString() straight, without touching the grid, it's throwing NULL object exception.

:beer:

Smith

Please check my reply to Luc.

:beer:

Luc Pattyn

Smith# wrote:

It requires me to "check" the checkbox at least once before checking it's VALUE

Not quite. There must be many ways to make Value hold an appropriate value, or to overcome a possible null. :)

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]

I only read formatted code with indentation, so please use PRE tags for code snippets.

I'm not participating in frackin' Q&A, so if you want my opinion, ask away in a real forum (or on my profile page).

Dr Walt Fair PE

Essentially .Value can have 3 values in the case of a CheckBox: true, false and null. Whenever you deal with DataGridView cell values, you need to check for null. Whether it's a CheckBox cell or not, accessing a null is bad.

CQ de W5ALT

Walt Fair, Jr., P. E. Comport Computing Specializing in Technical Engineering Software

Smith

Hi Walt Fair, thanks for your reply. Well,I'm still not convinced with the replies. The grid has been drawn on the screen, the rows have been created, the cells are displayed beautifully with checkboxes. Then why the "Value" has to be NULL? and why it's not NULL after I check the cell once?

:beer: