SamusevWinApp/MainCardForm.cs

using Microsoft.EntityFrameworkCore;
using System;
using System.Linq;
using System.Windows.Forms;

namespace samusev_42
{
    public partial class MainCardForm : Form
    {
        Ispr2522SamusevOvLazarev2Context context;

        public MainCardForm()
        {
            InitializeComponent();
        }

        protected override void OnLoad(EventArgs e)
        {
            base.OnLoad(e);
            context = new Ispr2522SamusevOvLazarev2Context();

            context.Products.Include(x => x.IdCategoryNavigation).Load();
            context.Products.Include(x => x.IdManufacturerNavigation).Load();
            context.Products.Include(x => x.IdProductNameNavigation).Load();
            context.Products.Include(x => x.IdSupplierNavigation).Load();
            context.Categories.Load();
            context.Manufacturers.Load();
            context.ProductNames.Load();
            context.Suppliers.Load();

            productBindingSource.DataSource = context.Products.Local.ToBindingList();
            categorySource.DataSource = context.Categories.Local.ToBindingList();
            manufacturerSource.DataSource = context.Manufacturers.Local.ToBindingList();
            product_nameSource.DataSource = context.ProductNames.Local.ToBindingList();
            SupplierSource.DataSource = context.Suppliers.Local.ToBindingList();

            Populate();
        }

        public void Populate()
        {
            flowLayoutPanel1.Controls.Clear();
            foreach (var item in productBindingSource)
            {
                if (item is Product p)
                {
                    CardForm card = new CardForm(p);
                    card.Click += (s, ev) => { productBindingSource.Position = productBindingSource.IndexOf(p); };
                    flowLayoutPanel1.Controls.Add(card);
                }
            }
        }

       
        private void SaveCardButton_Click(object sender, EventArgs e)
        {

        }

        private void CardEditButton_Click_1(object sender, EventArgs e)
        {
            if (productBindingSource.Current == null) return;

            var form = new EditForm();
            form.categoryBindingSource.DataSource = categorySource.DataSource;
            form.manufacturerBindingSource.DataSource = manufacturerSource.DataSource;
            form.productNameBindingSource.DataSource = product_nameSource.DataSource;
            form.supplierBindingSource.DataSource = SupplierSource.DataSource;
            form.productBindingSource.DataSource = productBindingSource.Current;

            if (form.ShowDialog() == DialogResult.OK)
            {
                productBindingSource.EndEdit();
                context.SaveChanges();
                Populate(); 
            }
        }

        private void CardDeleteButton_Click_1(object sender, EventArgs e)
        {
            if (productBindingSource.Current == null) return;

            var result = MessageBox.Show("Удалить этот товар?", "Подтверждение", MessageBoxButtons.YesNo);
            if (result == DialogResult.Yes)
            {
                productBindingSource.RemoveCurrent();
                context.SaveChanges();
                Populate(); 
            }
        }

        private void CardAddButton_Click_1(object sender, EventArgs e)
        {
            var newProduct = new Product();
            newProduct.Article = "";
            newProduct.Unit = "шт.";
            newProduct.Description = "-";
            newProduct.Photo = "";
            newProduct.Price = 0;
            newProduct.Count = 0;
            newProduct.Discount = 0;

            var form = new EditForm();
            form.categoryBindingSource.DataSource = categorySource;
            form.manufacturerBindingSource.DataSource = manufacturerSource;
            form.productNameBindingSource.DataSource = product_nameSource;
            form.supplierBindingSource.DataSource = SupplierSource;
            form.productBindingSource.DataSource = newProduct;

            if (form.ShowDialog() == DialogResult.OK)
            {
                try
                {
                    if (newProduct.IdProductName <= 0)
                        throw new System.ComponentModel.DataAnnotations.ValidationException("Выберите название товара!");

                    context.Products.Add(newProduct);
                    context.SaveChanges();

                    Populate(); 
                    MessageBox.Show("Товар добавлен!");
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message);
                    context.Entry(newProduct).State = EntityState.Detached;
                }
            }
        }
    }
}