Entity Change Tracking using DbContext in .Net Core
To save change Log For A Table Entry we have:
-
Create data model
public class ChangeLog { [Key] public int Id { get; set; } public string TableName { get; set; } public string ColumnName { get; set; } public string RowId { get; set; } public string State { get; set; } public string OldValue { get; set; } public string NewValue { get; set; } public DateTime DateChanged { get; set; } } -
modyfiy DbContex 2.1 Add table object
public virtual DbSet<ChangeLog> ChangeLogs { get; set; }
2.2 Overide SaveChanges
public override int SaveChanges()
{
var modifiedEntities = ChangeTracker.Entries().ToList();
var now = DateTime.Now;
string rowId = null;
foreach (var change in modifiedEntities)
{
var entityName = change.Entity.GetType().Name;
var entityState = change.State;
foreach (var prop in change.OriginalValues.Properties.Cast<IProperty>().Select((r, i) => new { Name = r.Name, Index = i }))
{
rowId = change.OriginalValues["Id"].ToString();
if (entityState == EntityState.Modified)
{
var originalValue = change.OriginalValues[prop.Name].ToString();
var currentValue = change.CurrentValues[prop.Name].ToString();
if (originalValue != currentValue)
{
ChangeLog log = new ChangeLog()
{
TableName = entityName,
ColumnName = prop.Name,
RowId = rowId,
State = entityState.ToString(),
OldValue = originalValue,
NewValue = currentValue,
DateChanged = now
};
ChangeLogs.Add(log);
}
}
else if (entityState == EntityState.Deleted)
{
if(prop.Index == 1)
{
ChangeLog log = new ChangeLog()
{
TableName = entityName,
ColumnName = "",
RowId = rowId,
State = entityState.ToString(),
OldValue = "",
NewValue = "",
DateChanged = now
};
ChangeLogs.Add(log);
}
}
}
}
return base.SaveChanges();
}