Set up logging Leave feedback

By default logging is disabled when processing documents but product provides a way to save the log with embedded implementation to save events to console and file.

There is an interface that we can utilize:

• ILogger - defines the interface for logging different process event like errors, warnings and information messages (traces).

There are classes that we can utilize:

• ConsoleLogger - defines the methods that are required for logging to console.
• FileLogger - defines the methods that are required for logging to file.

There are 3 types of messages in the log file:

• Error - for unrecoverable exceptions
• Warning - for recoverable/expected/known exceptions
• Trace - for general information

The LogLevel property of SignatureSettings decides which kinds of messages reach the logger. The values are flags that can be combined: Error, Warning and Trace. The default, LogLevel.All, logs all three, and LogLevel.None logs nothing.

var settings = new SignatureSettings(new ConsoleLogger())
{
    // Errors and warnings, without the step-by-step traces.
    LogLevel = LogLevel.Error | LogLevel.Warning
};

The level only filters the log: exceptions are thrown as before.

Note

LogLevel takes effect starting with GroupDocs.Signature for .NET 26.9. In earlier versions every error, warning and trace reached the logger, whatever the value.

In this example, we’ll log into the file so we need to use FileLogger class.

// Create logger and specify the output file
FileLogger fileLogger = new FileLogger("output.log");

// Create SignatureSettings and specify FileLogger
var settings = new SignatureSettings(fileLogger);

using (var signature = new Signature("sample.docx", settings))
{
    var options = new QrCodeSignOptions("JohnSmith");
    // sign document to file
    signature.Sign(outputFilePath, options);
}

In this example, we’ll log into the console so we need to use ConsoleLogger class.

// Create logger that writes to the console
var consoleLogger = new ConsoleLogger();

// Create SignatureSettings and specify ConsoleLogger instance
var settings = new SignatureSettings(consoleLogger);

using (var signature = new Signature("sample.docx", settings))
{
    var options = new QrCodeSignOptions("JohnSmith");
    // sign document to file
    signature.Sign(outputFilePath, options);
}

GroupDocs.Signature writes a warning when an operation succeeds but the result may not be what you expect. Warnings are logged when LogLevel includes LogLevel.Warning, as the default does. Starting with GroupDocs.Signature for .NET 26.9, you may see these warnings:

See “Certificates outside their validity period” in Pdf Digitally signing for the AllowExpired and AllowNotYetValid properties.