Modify values on-the-fly during SqlAdapter.Fill( )
- by Timothy
What would the proper way be to modify values on the fly as they are loaded into a DataTable by SqlAdapter.Fill()?
I have globalized my application's log messages. An integer indicating the event type and serialized data relevant to the event is stored in the database as show below. When I display the logged events through a DataGridView control to the user, I interpolate the data to a formatting string.
event_type event_timestamp event_details
============================================
3 2010-05-04 20:49:58 jsmith
1 2010-05-04 20:50:42 jsmith
...
I am currently iterating through the DataTable's rows to format the messages.
public class LogDataTable : DataTable
{
public LogDataTable()
{
Locale = CultureInfo.CurrentCulture;
Columns.AddRange(new DataColumn[] {
new DataColumn("event_type", typeof(Int32)),
new DataColumn("event_timestamp", typeof(DateTime)),
new DataColumn("event_details", typeof(String))});
}
}
...
using (SqlDataAdapter adapter = new SqlDataAdapter(...))
{
adapter.SelectCommand.Parameters.AddRange(new Object[] {
...
});
adapter.Fill(table);
}
foreach (DataRow row in table.Rows)
{
switch ((LogEventType)row["event_type"])
{
case LogEventType.Create:
row["event_details"] = String.Format(Resources.Strings.LogEventCreateMsg, row["event_details"];
break;
case LogEventType.Create:
row["event_details"] = String.Format(Resources.Strings.LogEventCreateMsg, row["event_details"];
break;
...
The end result as displayed would resemble:
Type Date and Time Details
====================================================================
[icon] 2010-05-04 20:49:58 Failed login attempt with username jsmith
[icon] 2010-05-04 20:50:42 Successful login with username jsmith
...
It seems wasteful to iterate the result set twice-- once as the table is filled by the adapter, and again to perform the replacements. I would really like to do the replacement on-the-fly in my LogDataTable class as it is being populated.
I have tried overriding an OnRowChanging method in LogDataTable, which throws an InRowChangingEventException.
protected override void OnRowChanging(DataRowChangeEventArgs e)
{
base.OnRowChanging(e);
switch ((LogEventType)row["event_type"])
...
I have tried overriding an OnRowChanged method, which throws a StackOverflowException (I assume changing it re-triggers the method ad infinitum?).
I have tried overriding an OnTableNewRow method, which does not throw an exception but appears not to be invoked (I assume only when a user adds a row in the view, which I've prevented).
I'd greatly appreciate any assistance anyone can give me.
