Question

I have a method which select rows in datagrid and change value of checkboxcolumn:

foreach (DataGridViewRow gridRow in dataGridView1.Rows)
            {
                if (_selectedIDs != null)
                    foreach (long id in _selectedIDs)
                    {

                        gridRow.Selected = false;
                        if ((long)((DataRowView)gridRow.DataBoundItem)["ObjectD"] == id)
                            gridRow.Selected = true;
                    }

                if (_checkedIDs != null)
                    foreach (long id in _checkedIDs)
                    {

                        ((DataRowView)gridRow.DataBoundItem)["Choosen"] = 0;
                        if ((long)((DataRowView)gridRow.DataBoundItem)["ObjectD"] == id)
                            ((DataRowView)gridRow.DataBoundItem)["Choosen"]=true;
                    }
            }
            dataGridView1.Refresh();

When I’m debugging this code I see that it enters in lines

gridRow.Selected = true;

and

((DataRowView)gridRow.DataBoundItem)["Choosen"]=true;

and in quickwatch I see that properties of those rows are changed.

But after execution of this code I still have only one row selected

Does anyone have an idea what’s wrong with this code?

Answer 1

In addition to the MultiSelect, you might want to make sure that the class you databind implements the INotifyPropertyChanged interface.
You also could set the selected = false before you start looping, or you will overwrite your selection every time…

        foreach (DataGridViewRow gridRow in dataGridView1.Rows)
        {
            if (_selectedIDs != null)
                // *****
                gridRow.Selected = false;
                // *****
                foreach (long id in _selectedIDs)
                {

                    if ((long)((DataRowView)gridRow.DataBoundItem)["ObjectD"] == id)
                        gridRow.Selected = true;
                }

            if (_checkedIDs != null)
                foreach (long id in _checkedIDs)
                {

                    ((DataRowView)gridRow.DataBoundItem)["Choosen"] = 0;
                    if ((long)((DataRowView)gridRow.DataBoundItem)["ObjectD"] == id)
                        ((DataRowView)gridRow.DataBoundItem)["Choosen"]=true;
                }
        }