Need to insert duplicate records in Entity Framework with list

Question

I am trying to insert duplicate record using EF by below code

db.Set<TEntity>().AddRange(lstEntity);
db.SaveChanges();

lstEntity is a list of type TEntity.

Suppose, I have 6 elements in lstEntity, 3 of them are duplicate.

On the first line in AddRange it only adds 4 elements, because 3 elements were duplicate so it adds 1 (3 duplicated) + 3 distinct records so it becomes 4.

And therefore, it inserts only 4 records in the DB.

I need to allow this duplicate thing and want to insert all the 6 elements (duplicate and distinct both).

Answer 1

Entity Framework he is doing his job correctly, the object services will find the duplicated items and insert them one time in db. Think about it! an entity represents a row in your table with an Id. You cannot insert the same row multiple times, you need a new primary key(Id).

You can clone your entity and add it to the DbContext or use this

Your name is arabic so I think you can understand the arabic langauge just watch my tutorial this will answer all your quesitons:

Video

---

Example for Clone:

public class City
{
  [Key]
  [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
  public int Id { get; set; }

  public City Clone()
  {
    return (City)MemberwiseClone();
  }

}

public class MyDbContext : DbContext
{
  public MyDbContext(string connectionString)
        : base("name=" + connectionString)
  {
  }

  public DbSet<City> Cities { get; set; }
}

public static void Main(string[] args)
{
  Database.SetInitializer(new DropCreateDatabaseIfModelChanges<MyDbContext>());

  using (var myDbContext = new MyDbContext())
  {
    // This will add the city one time  => the bug
    var city = new City();

    var list = new List<City>();
    list.Add(city);
    list.Add(city);

    myDbContext.Cities.AddRange(list);
    myDbContext.SaveChanges();

    // This will add the city 2 times
    city = new City();
    var city2 = new City();

    list = new List<City>();
    list.Add(city);
    list.Add(city2);

    myDbContext.Cities.AddRange(list);
    myDbContext.SaveChanges();

    // This will add the clonned city1 and city=> Fix!
    var cityCloned1 = city.Clone();
    var cityCloned2 = city2.Clone();

    list = new List<City>();
    list.Add(cityCloned1);
    list.Add(cityCloned2);

    myDbContext.Cities.AddRange(list);
    myDbContext.SaveChanges();

  }

}

The result: