Design advise needed on editing and filtering a datagridview

Question

I have a design question that involves DataGridView and DataTable, bound by a BindingSource in a WinForms application. The DataTable is populated by a sql server table.

Answer 1

The filter shouldn't affect the loop. For example, in the following code I set the DataGridView.DataSource from a DataTable that has an applied filter and loop through the table, printing values:

DataTable dt = new DataTable();

dt.Columns.Add("Name", typeof(string));
dt.Columns.Add("Quantity", typeof(int));

dt.Rows.Add("Foo", 1);
dt.Rows.Add("Bar", 2);
dt.Rows.Add("Baz", 3);

string filterField = "Name";
string filterText = "B";
dt.DefaultView.RowFilter = string.Format("[{0}] LIKE '%{1}%'", filterField, filterText);

this.dataGridView1.DataSource = dt;

foreach (DataRow row in dt.Rows)
{
    Console.WriteLine("{0}", row.ItemArray[0]);
}

With the filter, the DataGridView displays only select entries. But looping through the DataTable rows still prints every entry.

Therefore, when handling binding such as a BindingSource, after the DataGridView is already sourced, you might change your filter like so to have a dynamic searching option:

private void textBox1_TextChanged(object sender, EventArgs e)
{
    BindingSource bs = this.dataGridView1.DataSource as BindingSource;
    DataTable dt = bs.DataSource as DataTable;
    dt.DefaultView.RowFilter = string.Format("[{0}] LIKE '{1}%'", "Name", this.textBox1.Text);
}