C# auditoria

context.cs

public override int SaveChanges(bool acceptAllChangesOnSuccess)
        {
            OnBeforeSaving();
            return base.SaveChanges(acceptAllChangesOnSuccess);
        }

        public override Task<int> SaveChangesAsync(bool acceptAllChangesOnSuccess, CancellationToken cancellationToken = default(CancellationToken))
        {
            OnBeforeSaving();
            return base.SaveChangesAsync(acceptAllChangesOnSuccess, cancellationToken);
        }

        private void OnBeforeSaving()
        {
            var entries = ChangeTracker.Entries();
            foreach (var entry in entries)
            {
                if (entry.Entity is IAuditoria auditoria)
                {
                    var now = DateTime.Now;
                    switch (entry.State)
                    {
                        case EntityState.Deleted:
                            entry.State = EntityState.Unchanged;
                            auditoria.DataAlteracao = DateTime.Now;
                            auditoria.LoginAlteracao = auditoria.LoginExecutor;
                            auditoria.IsDeleted = true;
                            base.Add(new LogUpdate{ Login = auditoria.LoginExecutor, 
                                                    DataHora = DateTime.Now, Tabela = entry.Entity.ToString(), 
                                                    PK = Convert.ToInt32(entry.Property("Id").CurrentValue), 
                                                    objetoAnterior = JsonConvert.SerializeObject(entry.GetDatabaseValues().ToObject()), 
                                                    objetoNovo = JsonConvert.SerializeObject(entry.CurrentValues.ToObject()) });
                            break;

                        case EntityState.Modified:
                            auditoria.DataAlteracao = now;
                            auditoria.LoginAlteracao = auditoria.LoginExecutor;
                            base.Add(new LogUpdate{ Login = auditoria.LoginExecutor, 
                                                    DataHora = DateTime.Now, Tabela = entry.Entity.ToString(), 
                                                    PK = Convert.ToInt32(entry.Property("Id").CurrentValue), 
                                                    objetoAnterior = JsonConvert.SerializeObject(entry.GetDatabaseValues().ToObject()), 
                                                    objetoNovo = JsonConvert.SerializeObject(entry.CurrentValues.ToObject()) });
                            break;

                        case EntityState.Added:
                            auditoria.DataCriacao = now;
                            auditoria.LoginCriacao = auditoria.LoginExecutor;
                            break;
                    }
                }
            }

IAuditoria.cs

using System;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

namespace Models
{
    public interface IAuditoria
    {
        DateTime? DataCriacao {get; set;}
        string LoginCriacao {get; set;}
        DateTime? DataAlteracao {get; set;}
        string LoginAlteracao {get; set;}
        bool IsDeleted {get; set;}
        [NotMapped]
        string LoginExecutor {get; set;}
    }
}

logupdate.cs

using System;
using System.ComponentModel.DataAnnotations;

namespace Models
{
    public class LogUpdate
    {
        [Key]
        public int Id {get; set;}
        public string Login {get; set;}
        public DateTime DataHora {get; set;}
        public string Tabela {get; set;}
        public int PK {get; set;}
        public string objetoAnterior {get; set;}
        public string objetoNovo {get; set;}
    }
}