private void button1_Click(object sender, EventArgs e)
{
//Get the combo choice, if there is any.
string strGenre = cbxGenre.SelectedIndex > -1 ? cbxGenre.SelectedItem.ToString() : string.Empty;
//Declare the books array; though the actual return type is List<Books>, it actually gets casted into
//Book[] array.
Book[] lstBooks = null;
//Discard other filters, if user has entered a book id
if (!string.IsNullOrEmpty(txtID.Text))
{
lstBooks = bookService.GetBookByID(txtID.Text);
}
else
{
//Lets get books by filter.
lstBooks = bookService.Filter(Author: txtAuthor.Text, Title: TxtTitle.Text, Genre: strGenre);
}
//Set datasource, custom object.
dataGridView1.DataSource = lstBooks;
}