Question

我想知道是否存在使用EF 4.0记录每个对象的更改/添加/删除的通用方法。我知道你可以覆盖int SaveChanges（SaveOptions选项）方法，但我不确定我应该放在那里。

由于

Answer 1

您可以在上下文中处理SavingChanges事件，并使用context.ObjectStateManager.GetObjectStateEntries（EntityState）来获取有关更改的信息。此方法返回ObjectStateEntry的枚举，其中包含有关更改的信息。

Answer 2

这就是我发现here的原因，因为它不起作用，我对其进行了修改

private object GetPrimaryKeyValue(DbEntityEntry entry)
        {
            var objectStateEntry = ((IObjectContextAdapter)this).ObjectContext.ObjectStateManager.GetObjectStateEntry(entry.Entity);
            object o = objectStateEntry.EntityKey.EntityKeyValues[0].Value;
            return o;
        }

         private bool inExcludeList(string prop)
        {
            string[] excludeList = { "props", "to", "exclude" };
            return excludeList.Any(s => s.Equals(prop));
        }

        public int SaveChanges(User user, string UserId)
        {
            var modifiedEntities = ChangeTracker.Entries()
                .Where(p => p.State == EntityState.Modified).ToList();
            var now = DateTime.Now;

            foreach (var change in modifiedEntities)
            {

                var entityName = ObjectContext.GetObjectType(change.Entity.GetType()).Name;
                var primaryKey = GetPrimaryKeyValue(change);
                var DatabaseValues = change.GetDatabaseValues();

                foreach (var prop in change.OriginalValues.PropertyNames)
                {
                    if(inExcludeList(prop))
                    {
                        continue;
                    }

                    string originalValue = DatabaseValues.GetValue<object>(prop)?.ToString();
                    string currentValue = change.CurrentValues[prop]?.ToString();

                    if (originalValue != currentValue)
                    {
                        ChangeLog log = new ChangeLog()
                        {
                            EntityName = entityName,
                            PrimaryKeyValue = primaryKey.ToString(),
                            PropertyName = prop,
                            OldValue = originalValue,
                            NewValue = currentValue,
                            ModifiedByName = user.LastName + ", " + user.FirstName,
                            ModifiedById = UserId,
                            ModifiedBy = user,
                            ModifiedDate = DateTime.Now
                        };

                        ChangeLogs.Add(log);
                    }
                }
            }
            return base.SaveChanges();
        }



public class ChangeLog 
    {
        public int Id { get; set; }
        public string EntityName { get; set; }
        public string PropertyName { get; set; }
        public string PrimaryKeyValue { get; set; }
        public string OldValue { get; set; }
        public string NewValue { get; set; }
        public string ModifiedByName { get; set; }



        [ForeignKey("ModifiedBy")]
        [DisplayName("Modified By")]
        public string ModifiedById { get; set; }
        public virtual User ModifiedBy { get; set; }


        [Column(TypeName = "datetime2")]
        public DateTime? ModifiedDate { get; set; }
    }

使用覆盖的savechanges方法对实体进行EF 4.0 Logging更改

2 个答案: