C# how to fire DataGridView CellFormatting event from outside?

Question

I have a DGV that has some conditional formatting for values in all columns but the first N columns (Item columns). The first N columns (Category columns)have reference values for the rest of the table. Something like that:

Category1 Category2 Item1 Item2 Item3 Item4
1         2         1     2     1     2
56        57        57    56    56    56

I also have a dictionary that sets correspondence of headers of all the columns to the headers of the reference columns.

{Item1, Category1}
{Item2, Category1}
{Item3, Category1}
{Item4, Category2}

Each cell for Items1-4 is compared to the corresponding Category (using Dictionary) in the CellFormatting Event Handler, Then if it's a match, it colors the cell green, otherwise - red.

In other words, in the handler of CellFormatting event I use dictionary to check what values a particular column should have from N Reference columns.

Now I have a completely separate control (another DGV with comboboxes) that allows user to change that dictionary (switch what Category each Item belongs). How do I manually raise CellFormatting event when I change that dictionary?

This is my Event Handler for Cell Formatting:

        private void dataGridView_CellFormatting(object sender, DataGridViewCellFormattingEventArgs e)
        {

            try
            {

                if (e.ColumnIndex > N_of_ReferenceColumns)
                {

                    if (e.Value.ToString() == this.dataGridView.Rows[e.RowIndex].Cells[dataGridView.Columns[convertItemToCategory(dataGridView.Columns[e.ColumnIndex].Name)].Index].Value.ToString())
                    {

                        e.CellStyle.BackColor = Color.Green;
                        e.CellStyle.SelectionBackColor = Color.DarkGreen;
                    }
                    else
                    {
                        e.CellStyle.BackColor = Color.Red;
                        e.CellStyle.SelectionBackColor = Color.DarkRed;
                    }
                }
            }
            catch
            { }

        }

And this is my Handler on changing values in Combobox for Category for each of the Items:

        private void DictionarydataGridView_CellValueChanged(object sender, DataGridViewCellEventArgs e)
        {
            UpdateDictionary(DictionarydataGridView.Rows[e.RowIndex].Cells[1].Value.ToString(), DictionarydataGridView.Rows[e.RowIndex].Cells[0].Value.ToString());
        }

And this is how I update my dictionary and how I use it in conditional formatting logic:

    public static IDictionary<string, string> Dictionary = new Dictionary<string, string>();

        public void UpdateDictionary(string key, string value)
        {
            Dictionary[key] = value;

        }
        public static string convertItemToCategory(string key)
        {
            string value = "";
            if (Dictionary.TryGetValue(key.ToUpper(), out value))
            {
                return value;
            }
            else
            {
                return key.ToUpper();
            }

        }

What I need to do is when I update Dictionary, also raise CellFormatting event so that conditional formatting updates based on new selection.

One way would be to pack logic of update into a separate method, and then call it separately form each event handler, I'm not sure though what to do with all the e.CellStyle.BackColor and so on...

Any ideas?

Answer 1

A quick hack that never fails is to force the data grid to re-bind to the data source by resetting the data source.

This thread has lengthy discussions on the topic: C# refresh DataGridView when updating or inserted on another form

You could put a helper method on the form:

public void Refresh()
{
    datagridview1.DataSource = datagridview1.DataSource; // should re-evaluate all logic related to data bindings
    datagridview1.Refresh(); // forces the control to repaint
}

It's probably the most intensive solution but it should do the job.