Checkbox in DataGridView

GGuzdziol
GGuzdziol used Ask the Experts™
on
Hello!

I got a DataGridView, one column is set to checkbox. I want to grab event when those checkbox are being clicked on. Currently I'm trying to do it via CellContentClick, but I have no idea how to cast from (DataGridViewCellEventArgs^  e) to (DataGridViewCheckboxCell ^t). Of course I do not insist on using this particular event / method, just want to trace checkbox's value changes...

Thanks,
Grzegorz
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Commented:
C# code from MSDN samples looks like this:

private void DataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
   DataGridViewCell cell = DataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex];
}

I think that DataGridViewCheckboxCell can be get by casting:

DataGridViewCheckboxCell checkCell = (DataGridViewCheckboxCell)cell;

In C++/CLI this can look like this:

private void DataGridView1_CellContentClick(Object^ sender, DataGridViewCellEventArgs^ e)
{
   DataGridViewCell^ cell = DataGridView1->Rows[e->RowIndex]->Cells[e->ColumnIndex];

   DataGridViewCheckboxCell^ checkCell = (DataGridViewCheckboxCell^)cell;
}

Author

Commented:
Yes, that worked...

Sorry but anyway I'm stuck now - how do I determine status (true/false) of this checkbox? I'm really capable of reading, I have MSDN installed...I just cannot find it.

Commented:
bool checked = false;

if ( checkCell != nullPtr  &&  checkCell->Value != nullptr )
{
    checked = (bool)checkCell->Value;
}

Author

Commented:
I also think this should work...but it simply doesn't!

My current code is:

private: System::Void clc(System::Object^  sender, System::Windows::Forms::DataGridViewCellEventArgs^  e) {
                   if(e->ColumnIndex == 0) {
                         DataGridViewCell^ cell = this->dataGridView1->Rows[e->RowIndex]->Cells[e->ColumnIndex];

                         DataGridViewCheckBoxCell^ checkCell = (DataGridViewCheckBoxCell^)cell;
                         bool checked = false;

                         if((checkCell != nullptr)&&(checkCell->Value != nullptr)) {
                               checked = (bool)checkCell->Value;
                         }
                         if(checked) {
                               MessageBox::Show("yeah!");
                         }
                   }
             }

The behaviour is very strange for me. Sometimes it always shows messagebox, sometimes never. I guess that it is bad event that I put this code on (CellContentClick) but msdn says:
,,If you want to respond immediately when users click a check box cell, you can handle the DataGridView.CellContentClick event, but this event occurs before the cell value is updated. If you need the new value at the time of the click, one option is to calculate what the expected value will be based on the current value''
I don't understand.

Commented:
This means, this handler is called before value is changed. If checked value is false, new value will be true. If checked value is true, it will be false.
If you want to know new state, it is better to handle DataGridView.CellValueChanged event.

Author

Commented:
If it worked like You say (and as it's written in msdn) I could just negate this value and voila. But it doesn't...I'll take a look at CellValueChanged.
Commented:
BTW, you can get much more information about DataGridView in C# or VB .NET area. Such things are usually written in C# or VB. C++/CLI is used mostly for interoperability.
If you have some reasons to do this stuff in C++/CLI, you can ask syntax questions here, and general questions about database, controls like DataGridView in other .NET areas. C++/CLI developers don't work with this.

Author

Commented:
It was enough to take care about CurrentCellDirtyStateChanged while using CellValueChanged. Thanks.

Commented:
DataGridView dgv = sender as DataGridView;
            DataGridViewCell cell = dgv.Rows[e.RowIndex].Cells[e.ColumnIndex];
            bool isChecked = (bool)cell.EditedFormattedValue;

            if (isChecked)
            {
                //Checkbox is being checked                
            }
            else
            {
                //Checkbox is being unchecked
            }

Commented:
Updated Comment
***********************
private void dgv_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
            DataGridView dgv = sender as DataGridView;
            DataGridViewCell cell = dgv.Rows[e.RowIndex].Cells[e.ColumnIndex];
            bool isChecked = (bool)cell.EditedFormattedValue;

            if (isChecked)
            {
                //Checkbox is being checked                                
            }
            else
            {
                //Checkbox is being unchecked
            }
}

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