How to log changed values to database on all action? - entity-framework

Question

The controller above has a standard edit ActionResult. I simply find rows in a database by ID and update it. Before db.SaveChanges() there is log.Save() static function that saves all changes in model to separate tables in the database.It simply check old and new values from ChangeTracker.
The problem is, i want use log.Save() after db.SaveChanges(), not before, to be sure that data was really saved.
But after, in the ChangeTracker there aren't any changes so log.Save() doesn't have anything to save.
Controller:
[HttpPost]
public ActionResult edit(int id, MyModel model)
{
var hihi = db.MyModel.First(s => s.ID == model.ID);
hihi.col1 = model.col1;
hihi.col2 = model.col2;
...
log.Save(Log.ChangeType.Edit, db, id);
^ Here i save changes to log.
db.SaveChanges();
return RedirectToAction("Index");
}
Log Class:
public void Save(ChangeType changeType, DBContext parentContext, int id)
{
DBContext db = new DBContext();
foreach (System.Data.Entity.Infrastructure.DbEntityEntry ee in parentContext.ChangeTracker.Entries())
{
foreach (string column in ee.OriginalValues.PropertyNames)
{
string oldValue = ee.OriginalValues[column].ToString();
string newValue = ee.CurrentValues[column].ToString();
if (oldValue != newValue)
{
var model = new LogModel
{
Log_Time = DateTime.Now,
Log_Operator = User.Ope_ID,
Log_Table = ee.Entity.ToString().Replace("xxx.Models.", ""),
Log_Key = id,
Log_Column = column,
Log_Type = (int)changeType,
Log_OldValue = oldValue,
Log_NewValue = newValue
};
var log = db.Log.Add(model);
db.SaveChanges();
}
}
}
}
public enum ChangeType
{
Create = 1,
Delete = 2,
Edit = 3
}
... or maybe someone has another way to save all changes in a database to another table on all controller actions, so after the project release I can see what users do.
PS. I don't what user triggers.

Answer 1

SaveChanges in EF4 is virtual, so you can override it, add custom logging etc.

Answer 2

Why don't you use try{} catch{} within Log Class and change the return parameter from 'void' to 'bool'. This would return true if the db.SaveChanges() succeeds. Then within "ActionResult edit" use bool result = log.Save(Log.ChangeType.Edit, db, id); to retrieve if the log saved the changes, then use a simple if-sentence to validate if you can save all changes to db or not.