Audit trail: Web application

Fully implemented and can be improved more. I hope this may help someone :

public partial  class Entity:DbContext    {      public enum AuditActions {I,U,D}      public override int SaveChanges( )      {          ChangeTracker.DetectChanges();           ObjectContext ctx = ((IObjectContextAdapter)this).ObjectContext;          // string UserName = WindowsIdentity.GetCurrent().Name;          IPrincipal principal = Thread.CurrentPrincipal;          IIdentity identity = principal == null ? null : principal.Identity;          string name = identity == null ? "" : identity.Name;          //Thread.CurrentPrincipal = new GenericPrincipal(new GenericIdentity((userName), roles);          List<ObjectStateEntry> objectStateEntryList =              ctx.ObjectStateManager.GetObjectStateEntries(EntityState.Added                                                         | EntityState.Modified                                                         | EntityState.Deleted)              .ToList();          List<DBAudit> AuditList = new List<DBAudit>();          string Audittable = string.Empty;           foreach (ObjectStateEntry entry in objectStateEntryList)          {               Audittable = entry.EntitySet.ToString();               if (!entry.IsRelationship && Audittable!="Audit table name")              {                  //sIsAuditTble =entry.EntitySet="DBAudit"? true:false;                  switch (entry.State)                  {                      case EntityState.Added:                        AuditList=  LogDetails(entry, name, AuditActions.I);                          break;                      case EntityState.Deleted:                        AuditList=  LogDetails(entry, name, AuditActions.D);                          break;                      case EntityState.Modified:                        AuditList=  LogDetails(entry, name, AuditActions.U);                           break;                  }              }          }              using (var context = new ProjectTrackerEntities())              {                  for (int i = 0; i < AuditList.Count; i++)                  {                      context.DBAudits.Add(AuditList[i]);                      context.SaveChanges();                  }              }          return base.SaveChanges();      }      public List<DBAudit> LogDetails(ObjectStateEntry entry, string UserName, AuditActions action)      {          List<DBAudit> dbAuditList = new List<DBAudit>();        if (action == AuditActions.I)          {              var keyValues = new Dictionary<string, object>();              var currentValues = entry.CurrentValues;             // entry.Entity key = new EntityKey();                  DBAudit audit = new DBAudit();                  audit.AuditId = Guid.NewGuid().ToString();                  audit.RevisionStamp = DateTime.Now;                  audit.TableName = entry.EntitySet.Name;                  audit.UserName = UserName;                  audit.OldData = "";                  audit.Actions = action.ToString();                  for (int i = 0; i < currentValues.FieldCount; i++)                  {                  audit.ChangedColumns = audit.ChangedColumns + currentValues.GetName(i);                  audit.NewData = audit.NewData + currentValues.GetValue(i);                  audit.ChangedColumns = audit.ChangedColumns + ", ";                  audit.NewData = audit.NewData + ", ";                  }                  dbAuditList.Add(audit);                  //LogSave(audit);          }          else if (action == AuditActions.D)          {              var keyValues = new Dictionary<string, object>();              var DeletedValues = entry.OriginalValues;              // entry.Entity key = new EntityKey();              DBAudit audit = new DBAudit();              audit.AuditId = Guid.NewGuid().ToString();              audit.RevisionStamp = DateTime.Now;              audit.TableName = entry.EntitySet.Name;              audit.UserName = UserName;              audit.NewData = "";              audit.Actions = action.ToString();              for (int i = 0; i < DeletedValues.FieldCount; i++)              {                  audit.ChangedColumns = audit.ChangedColumns + DeletedValues.GetName(i);                  audit.OldData = audit.OldData + DeletedValues.GetValue(i);                  audit.ChangedColumns = audit.ChangedColumns + ", ";                  audit.OldData = audit.OldData + ", ";              }              dbAuditList.Add(audit);          }          else           {                  foreach (string propertyName in entry.GetModifiedProperties())                  {                      DBAudit audit = new DBAudit();                      DbDataRecord original = entry.OriginalValues;                      string oldValue = original.GetValue(original.GetOrdinal(propertyName)).ToString();                      CurrentValueRecord current = entry.CurrentValues;                      string newValue = current.GetValue(current.GetOrdinal(propertyName)).ToString();                      audit.AuditId = Guid.NewGuid().ToString();                      audit.RevisionStamp = DateTime.Now;                      audit.TableName = entry.EntitySet.Name;                      audit.UserName = UserName;                      audit.ChangedColumns = propertyName;                      audit.OldData = oldValue;                      audit.NewData = newValue;                      audit.Actions = action.ToString();                      dbAuditList.Add(audit);                      //LogSave(audit);                    }          }        return dbAuditList;      }    }

One option for a NoSQL database is RavenDB, using its "versioning bundle".

Though at this point it's probably too early, I recently listened to an interesting episode of Herding code where they talk with Eric Sink on about Veracity. As I understand, Veracity is part distributed version control system, and part NoSQL database. It is designed to be the backend to anything from a source control system to a wiki. It's been in development for a couple years, but is still effectively in pre-beta stages (as of Nov 2010).