ProjectLib/ProjectLibrary/Forms/FOrder.cs

using ProjectLibrary.Repositories;
using ProjectLibrary.Entites;
using System.Xml.Linq;
using ProjectLibrary.Repositores;
using System.Windows.Forms;

namespace ProjectLibrary.Forms
{
    public partial class FOrder : Form
    {
        private readonly IOrderRepository _orderRepository;
        private readonly IBookRepository _bookRepository;

        public FOrder(IOrderRepository orderRepository, IReaderRepository _readerRepository, IBookRepository bookRepository)
        {
            InitializeComponent();
            _orderRepository = orderRepository ?? throw new ArgumentNullException(nameof(orderRepository));
            _bookRepository = bookRepository ?? throw new ArgumentNullException(nameof(_bookRepository));
            comboBox.DataSource = _readerRepository.ReadReaders();
            comboBox.DisplayMember = "Name";
            comboBox.ValueMember = "Id";

            Book.DataSource = bookRepository.ReadBooks();
            Book.DisplayMember = "Name";
            Book.ValueMember = "Id";
        }

        private List<Book_Orders> CreateListBooksFromDataGrid()
        {
            var list = new List<Book_Orders>();
            foreach (DataGridViewRow row in dataGridViewBook.Rows)
            {
                if (row.Cells["Book"].Value == null)
                {
                    continue;
                }
                list.Add(Book_Orders.CreateEntity(0, Convert.ToInt32(row.Cells["Book"].Value), Convert.ToInt32(row.Cells["ColumnCount"].Value)));
            }
            return list;
        }

        private void ButtonSave_Click(object sender, EventArgs e)
        {
            try
            {
                if (comboBox.SelectedItem == null)
                {
                    throw new Exception("Не все поля заполнены.");
                }

                var order = Orders.CreateEntity(
                    0,
                    dtptxtReturnDate.Value,
                    Convert.ToInt32(comboBox.SelectedValue),
                    CreateListBooksFromDataGrid()
                );

                _orderRepository.CreateOrder(order);

                Close();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Ошибка при сохранении данных", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void ButtonCancel_Click(object sender, EventArgs e)
        {
            Close();
        }
    }
}