Debug Messaging System topic explains how to activate the debug messages in your application. However the default console output has very limited possibilities and can only be used effectively in console applications. To use debug messaging system in any environment db4o gives you an API to redirect debug output to another stream:
c#:
IConfiguration.SetOut(System.IO.TextWriter)
VB:
IConfiguration.SetOut(System.IO.TextWriter)
An example below shows how to create and use a log file for debug messages:
01private static void SetCarsWithFileOutput() 02
{ 03
// Create StreamWriter for a file 04
FileInfo f = new FileInfo("Debug.txt"); 05
StreamWriter debugWriter = f.CreateText(); 06
07
IConfiguration configuration = Db4oFactory.NewConfiguration(); 08
// Redirect debug output to the specified writer 09
configuration.SetOut(debugWriter); 10
11
// Set the debug message levet to the maximum 12
configuration.MessageLevel(3); 13
// Do some db4o operations 14
File.Delete(Db4oFileName); 15
IObjectContainer db = Db4oFactory.OpenFile(Db4oFileName); 16
try 17
{ 18
Car car1 = new Car("BMW"); 19
db.Set(car1); 20
Car car2 = new Car("Ferrari"); 21
db.Set(car2); 22
db.Deactivate(car1, 2); 23
IQuery query = db.Query(); 24
query.Constrain(typeof(Car)); 25
IObjectSet results = query.Execute(); 26
ListResult(results); 27
} 28
finally 29
{ 30
db.Close(); 31
debugWriter.Close(); 32
} 33
Db4oFactory.Configure().MessageLevel(0); 34
}
01Private Shared Sub SetCarsWithFileOutput() 02
' Create StreamWriter for a file 03
Dim f As FileInfo = New FileInfo("Debug.txt") 04
Dim debugWriter As StreamWriter = f.CreateText() 05
06
' Redirect debug output to the specified writer 07
Db4oFactory.Configure().SetOut(debugWriter) 08
09
' Set the debug message levet to the maximum 10
Db4oFactory.Configure().MessageLevel(3) 11
' Do some db4o operations 12
File.Delete(Db4oFileName) 13
Dim db As IObjectContainer = Db4oFactory.OpenFile(Db4oFileName) 14
Try 15
Dim car1 As Car = New Car("BMW") 16
db.Set(car1) 17
Dim car2 As Car = New Car("Ferrari") 18
db.Set(car2) 19
db.Deactivate(car1, 2) 20
Dim query As IQuery = db.Query() 21
query.Constrain(GetType(Car)) 22
Dim results As IObjectSet = query.Execute() 23
ListResult(results) 24
Finally 25
db.Close() 26
debugWriter.Close() 27
End Try 28
Db4oFactory.Configure().MessageLevel(0) 29
End Sub
Using a log file for debug messages has several advantages:
You can always switch back to the default setting using:
c#:
IConfiguration.SetOut(System.Console.Out)
VB:
IConfiguration.SetOut(System.Console.Out)