TimestampedDbContext.cs

using CRMProject.Domain;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.ChangeTracking;
using System;

namespace Infrastructure.Data
{
    public class AppDbContext : DbContext
    {
        public DbSet<Contact> Contacts { get; set; }

        public AppDbContext(DbContextOptions<AppDbContext> options) : base(options)
        {
        }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            foreach (var entityType in modelBuilder.Model.GetEntityTypes())
            {
                if (typeof(ITimestamped).IsAssignableFrom(entityType.ClrType))
                {
                    modelBuilder.Entity(entityType.Name).Property<DateTime>("CreatedAt");
                    modelBuilder.Entity(entityType.Name).Property<DateTime>("UpdatedAt");
                }
            }
        }

        public override int SaveChanges()
        {
            TimestampChanges();
            return base.SaveChanges();
        }

        private void TimestampChanges()
        {
            var now = DateTime.Now;

            foreach (var entry in ChangeTracker.Entries<ITimestamped>())
            {
                if (entry.State == EntityState.Added)
                {
                    entry.Property("CreatedAt").CurrentValue = now;
                }

                if (entry.State == EntityState.Added || entry.State == EntityState.Modified)
                {
                    entry.Property("UpdatedAt").CurrentValue = now;
                }
            }
        }
    }
}