public static void Initialize(EfDbContext context) { if (context.Products.Any()) { return; } var newCategories = new List <Category> { new Category { Name = "TV" }, new Category { Name = "Phone" }, new Category { Name = "Laptop" } }; newCategories.ForEach(c => context.Categories.Add(c)); context.SaveChanges(); var newSuppliers = new List <Supplier> { new Supplier { Name = "Apple", City = "San Francisco" }, new Supplier { Name = "Samsung", City = "Seoul" }, new Supplier { Name = "Electron", City = "Seoul" } }; newSuppliers.ForEach(s => context.Suppliers.Add(s)); context.SaveChanges(); var newProducts = new List <Product> { new Product { Name = "IPhone", CategoryId = 2, SupplierId = 1, CreationDate = DateTime.Today, Price = 500 }, new Product { Name = "Galaxy", CategoryId = 2, SupplierId = 2, CreationDate = DateTime.Today, Price = 400 }, new Product { Name = "MacBook", CategoryId = 3, SupplierId = 1, CreationDate = DateTime.Today, Price = 1000 }, new Product { Name = "Samsung TV", CategoryId = 1, SupplierId = 2, CreationDate = DateTime.Today, Price = 600 }, new Product { Name = "Simple TV", CategoryId = 1, SupplierId = 3, CreationDate = DateTime.Today, Price = 200 }, new Product { Name = "Samsung Laptop", CategoryId = 3, SupplierId = 2, CreationDate = DateTime.Today, Price = 800 } }; newProducts.ForEach(p => context.Products.Add(p)); context.SaveChanges(); }