Язык программирования C#9 и платформа .NET5

 {
  public static class SampleData
  {
  }
 }

Класс SampleData содержит пять статических методов, которые создают выборочные данные:

 {
  new {Id = 1, PersonalInformation = new {FirstName = "Dave",
  LastName = "Brenner"}},
  new {Id = 2, PersonalInformation = new {FirstName = "Matt",
  LastName = "Walton"}},
  new {Id = 3, PersonalInformation = new {FirstName = "Steve",
  LastName = "Hagen"}},
  new {Id = 4, PersonalInformation = new {FirstName = "Pat",
  LastName = "Walton"}},
  new {Id = 5, PersonalInformation = new {FirstName = "Bad",
  LastName = "Customer"}},
 };

 public static List<Make> Makes => new
 {
  new {Id = 1, Name = "VW"},
  new {Id = 2, Name = "Ford"},
  new {Id = 3, Name = "Saab"},
  new {Id = 4, Name = "Yugo"},
  new {Id = 5, Name = "BMW"},
  new {Id = 6, Name = "Pinto"},
 };

 public static List<Car> Inventory => new
 {
  new {Id = 1, MakeId = 1, Color = "Black", PetName = "Zippy"},
  new {Id = 2, MakeId = 2, Color = "Rust", PetName = "Rusty"},
  new {Id = 3, MakeId = 3, Color = "Black", PetName = "Mel"},
  new {Id = 4, MakeId = 4, Color = "Yellow", PetName = "Clunker"},
  new {Id = 5, MakeId = 5, Color = "Black", PetName = "Bimmer"},
  new {Id = 6, MakeId = 5, Color = "Green", PetName = "Hank"},
  new {Id = 7, MakeId = 5, Color = "Pink", PetName = "Pinky"},
  new {Id = 8, MakeId = 6, Color = "Black", PetName = "Pete"},
  new {Id = 9, MakeId = 4, Color = "Brown", PetName = "Brownie"},
  new {Id = 10, MakeId = 1, Color = "Rust", PetName = "Lemon",
  IsDrivable = false},
 };

 public static List<Order> Orders => new
 {
  new {Id = 1, CustomerId = 1, CarId = 5},
  new {Id = 2, CustomerId = 2, CarId = 1},
  new {Id = 3, CustomerId = 3, CarId = 4},
  new {Id = 4, CustomerId = 4, CarId = 7},
  new {Id = 5, CustomerId = 5, CarId = 10},
 };

 public static List<CreditRisk> CreditRisks => new
 {
  new
  {
  Id = 1,
  CustomerId = Customers[4].Id,
  PersonalInformation = new
  {
  FirstName = Customers[4].PersonalInformation.FirstName,
  LastName = Customers[4].PersonalInformation.LastName
  }
  }
 };

Загрузка выборочных данных

Внутренний метод SeedData в классе SampleDatalnitializer добавляет данные из методов класса SampleData к экземпляру ApplicationDbContext и сохраняет данные в базе данных:

 internal static void SeedData(ApplicationDbContext context)
 {
  try
  {
  ProcessInsert(context, context.Customers!, SampleData.Customers);
  ProcessInsert(context, context.Makes!, SampleData.Makes);
  ProcessInsert(context, context.Cars!, SampleData.Inventory);
  ProcessInsert(context, context.Orders!, SampleData.Orders);
  ProcessInsert(context, context.CreditRisks!, SampleData.CreditRisks);
  }
  catch (Exception ex)
  {
  Console.WriteLine(ex);
  // Поместить сюда точку останова, чтобы выяснить,
  // в чем заключается проблема.
  throw;
  }
  static void ProcessInsert<TEntity>(
  ApplicationDbContext context,
  DbSet<TEntity> table,
  List<TEntity> records) where TEntity : BaseEntity
  {
  if (table.Any)
  {
  return;
  }
  IExecutionStrategy strategy = context.Database.CreateExecutionStrategy;
  strategy.Execute( =>
  {
  using var transaction = context.Database.BeginTransaction;
  try
  {
  var metaData = context.Model.FindEntityType(typeof(TEntity).FullName);
  context.Database.ExecuteSqlRaw(
  $"SET IDENTITY_INSERT {metaData.GetSchema}.
  {metaData.GetTableName} ON");
  table.AddRange(records);
  context.SaveChanges;
  context.Database.ExecuteSqlRaw(
  $"SET IDENTITY_INSERT {metaData.GetSchema}.