// Entity Framework Extensions

// Doc: https://entityframework-extensions.net/bulk-merge

​

// @nuget: Microsoft.EntityFrameworkCore.SqlServer

// @nuget: Z.EntityFramework.Extensions.EFCore

​

using Microsoft.EntityFrameworkCore;

using System.Collections.Generic;

using Microsoft.Data.SqlClient;

using System;

public class Program

{

    public static void Main()

    {

        using (var context = new EntityContext())

        {

            context.Database.EnsureCreated();

        }

        SeedCustomers(2);

        var customers = GenerateCustomers(5);

        using (var context = new EntityContext())

        {

            FiddleHelper.WriteTable("1 - Customers Before", context.Customers.AsNoTracking());

            context.BulkMerge(customers, options => options.IgnoreOnMergeUpdateExpression = c => new { c.CreatedDate } );

​

            FiddleHelper.WriteTable("2 - Customers After", context.Customers.AsNoTracking());

        }

    }

    public static List<Customer> GenerateCustomers(int count, bool useOld = false) 

    {

        List<Customer>  list = new List<Customer>();

            var date = useOld ? DateTime.Now.AddDays(-2) : DateTime.Now;

        for(int i = 0; i < count; i++)

        {

            list.Add(new Customer() { CustomerID = (i + 1), Name = (useOld ? "Old_" : "") + "Customer_" + i, CreatedDate = date, UpdatedDate = date});

        }

        return list;

    }

    public static void SeedCustomers(int count) 

    {

        var customers = GenerateCustomers(count, true);

        new EntityContext().BulkInsert(customers);

    }

    public class EntityContext : DbContext

    {

        public EntityContext() 

        {

        }

​

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)

        {

            optionsBuilder.UseSqlServer(new SqlConnection(FiddleHelper.GetConnectionStringSqlServer()));

​

            base.OnConfiguring(optionsBuilder);

        }

        public DbSet<Customer> Customers { get; set; }

    }

    public class Customer

    {

        public int CustomerID { get; set; }

        public string Name { get; set; }

        public DateTime? CreatedDate { get; set; }

        public DateTime? UpdatedDate { get; set; }

    }

}