C# Efficient way to check datagridview checkbox column for checked values

Question

I have a datagridview and a checkbox column attached to it. If the user checks a few rows and then presses a button, I would like to be able to get a certain cell value from each row where the box was ticked.

Something maybe like this:

foreach (DataGridViewRow row in dataGridView1.Rows)
{
    if (Convert.ToBoolean(row.Cells[CheckBoxColumn1.Name].Value) == true)
    {
        //...
    }
}

The problem is that the datagridview might contain up to 3000 or 4000 rows. I would like to see if there is a faster way to get the checked rows, other than to iterate through all the rows for the grid.

3000 or 4000 rows is not much. Do you have an actual performance problem? — paparazzo
– paparazzo, Commented Jun 8, 2016 at 16:17
@LarsTech It is the user's wish. And they will also be able to filter through that. — Iason
– Iason, Commented Jun 8, 2016 at 16:18
@Paparazzi I'm still in the design stage of this, I don't think it would create a bottleneck, but if there's a better way in terms of performance I would prefer it. — Iason
– Iason, Commented Jun 8, 2016 at 16:19
You should avoid premature optimization. If you are worried about performance then DataGridView and WinForms would certainly not be my pick. You have picked a very heavy weight control and you are worried about the time to iterate row. — paparazzo
– paparazzo, Commented Jun 8, 2016 at 16:24

Fabio · Accepted Answer · 2016-06-08 16:43:23Z

2

If you don't want to iterate all rows, then use temporary list of checked rows.
Then after button was clicked use values from that List

HashSet<DataGridViewRow> _CheckedRows = new HashSet<DataGridViewRow>();

private void DataGridView_CellEndEdit(object sender, DataGridViewCellEventArgs e)
{
    if (DataGridView.Columns[e.ColumnIndex].Name.Equals(CheckBoxColumn1.Name) == false)
        return;

    DataGridViewRow row = DataGridView.Rows[e.RowIndex];
    if (Convert.ToBoolean(row.Cells[CheckBoxColumn1.Name].Value) == true)
    {
        _CheckedRows.Add(row);
    }
    else
    {
        _CheckedRows.Remove(row);
    }
}

edited Jun 8, 2016 at 16:43

answered Jun 8, 2016 at 16:34

Fabio

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1 Comment

Alexander Petrov Over a year ago

Cool! I was late for a second with a similar answer.

omerts · Accepted Answer · 2016-06-08 16:27:35Z

You could manage your own list of checked rows. You would bind to the dataGridView1.CellClick event, and add/remove rows from the list:

var checkedRows = new List<DataGridViewRow>();

dataGridView1.CellClick += (sender, args) =>
{
    if (args.RowIndex != YOUR_CHECKBOX_COLUMN_INDEX)
    {
        return;
    }

    var cell = dataGridView1[args.ColumnIndex, args.RowIndex];

    if (cell.Value == null)
    {
        cell.Value = false;
    }

    cell.Value = !(bool)cell.Value;

    if ((bool)cell.Value)
    {
        checkedRows.Add(dataGridView1.Rows[args.RowIndex]);
    }
    else
    {
        checkedRows.Remove(dataGridView1.Rows[args.RowIndex]);
    }
};

All you have to do then is:

foreach (DataGridViewRow row in checkedRows)
{
    //...
}

Abdellah OUMGHAR · Accepted Answer · 2016-06-08 16:14:59Z

0

You can use Linq like this :

var checkedRows = from DataGridViewRow r in dataGridView1.Rows
                  where Convert.ToBoolean(r.Cells[CheckBoxColumn1.Name].Value) == true
                  select r;

foreach (var row in checkedRows)
{
    //
}

answered Jun 8, 2016 at 16:14

Abdellah OUMGHAR

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1 Comment

paparazzo Over a year ago

Cleaner syntax but I doubt it is faster

Slai · Accepted Answer · 2016-06-08 18:39:00Z

0

Using CheckBoxColumn1.Name instead of CheckBoxColumn1.Index seems like a tiny bottleneck to me.

To avoid the casting to DataGridViewRow and Boolean, my suggestion is something like (not tested):

int colIndex = CheckBoxColumn1.Index; // or dataGridView1.Columns.IndexOf(CheckBoxColumn1.Name) ?
for ( int r = 0; r < dataGridView1.RowCount; r++ )
{
    if ( true.Equals( dataGridView1[colIndex, r].Value ) )
    {
        //...
    }
}

The other answers that use cell events are better because the list of checked rows will be ready when needed, but also can be a bit harder to maintain/debug depending on how you do the filtering and rest. Here is my version:

private HashSet<int> checkedRowIndexes = new HashSet<int>();

private void dataGridView1_CellValueChanged(object sender, DataGridViewCellEventArgs e)
{
    if ( e.ColumnIndex == CheckBoxColumn1.Index ) 
    {
        if ( true.Equals( dataGridView1[CheckBoxColumn1.Index, e.RowIndex].Value ) )
            checkedRowIndexes.Add(e.RowIndex);
        else 
            checkedRowIndexes.Remove(e.RowIndex);
    }
}

answered Jun 8, 2016 at 18:39

Slai

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1 Comment

Slai Over a year ago

@Fabio compiles for me msdn.microsoft.com/en-us/library/0syx5449. The alternatives if needed are cell.Value.Equals(true) or object.Equals( cell.Value, true )

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