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:
01public static void SetCarsWithFileOutput() 02
{ 03
// Create StreamWriter for a file 04
FileInfo f = new FileInfo("Debug.txt"); 05
StreamWriter debugWriter = f.CreateText(); 06
07
// Redirect debug output to the specified writer 08
Db4oFactory.Configure().SetOut(debugWriter); 09
10
// Set the debug message levet to the maximum 11
Db4oFactory.Configure().MessageLevel(3); 12
// Do some db4o operations 13
File.Delete(YapFileName); 14
IObjectContainer db = Db4oFactory.OpenFile(YapFileName); 15
try 16
{ 17
Car car1 = new Car("BMW"); 18
db.Set(car1); 19
Car car2 = new Car("Ferrari"); 20
db.Set(car2); 21
db.Deactivate(car1, 2); 22
IQuery query = db.Query(); 23
query.Constrain(typeof(Car)); 24
IObjectSet results = query.Execute(); 25
ListResult(results); 26
} 27
finally 28
{ 29
db.Close(); 30
debugWriter.Close(); 31
} 32
Db4oFactory.Configure().MessageLevel(0); 33
}
01Public 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(YapFileName) 13
Dim db As IObjectContainer = Db4oFactory.OpenFile(YapFileName) 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)