lang__logger_message

All logging in BookStore MUST use the LoggerMessage source generator pattern for performance and consistency. Logs are organized by domain in separate partial classes.

Structure

Logs are organized in src/BookStore.ApiService/Infrastructure/Logging/Log.<Domain>.cs:

• Each domain (Books, Users, etc.) is a nested partial class inside Log
• Use appropriate log levels: Information, Warning, Error, Debug
• Include relevant parameters for structured logging
• Use descriptive method names in past tense for completed actions

Steps

1. Identify Domain

   • Determine which domain your logging belongs to (Books, Authors, Users, etc.)
   • Existing domains: Books, Authors, Publishers, Categories, Users, Email, Tenants, Notifications, Infrastructure, Maintenance, Seeding
   • Create new domain file if needed: Log.<YourDomain>.cs

2. Add Log Method

   • Open or create Infrastructure/Logging/Log.<Domain>.cs
   • Add a new partial method with [LoggerMessage] attribute
   • Template: See templates/Log.Domain.cs for structure
   • Include all relevant parameters for context

3. Choose Log Level

   • LogLevel.Information: Success operations, normal flow
   • LogLevel.Warning: Validation failures, recoverable errors, suspicious activity
   • LogLevel.Error: Exceptions, failures requiring attention
   • LogLevel.Debug: Detailed diagnostic information

4. Use in Code

   • Inject ILogger<YourClass> in constructor
   • Call: Log.<Domain>.<MethodName>(logger, params...)
   • For errors: Exception parameter comes after logger, before other params

Examples

Information Level:

[LoggerMessage(
    Level = LogLevel.Information,
    Message = "Book created successfully: Id={BookId}, Title={Title}")]
public static partial void BookCreated(
    ILogger logger,
    Guid bookId,
    string title);

Error Level with Exception:

[LoggerMessage(
    Level = LogLevel.Error,
    Message = "Failed to create book: Title={Title}")]
public static partial void BookCreationFailed(
    ILogger logger,
    Exception ex,
    string title);

Usage in Handler:

public class CreateBookHandler(ILogger<CreateBookHandler> logger)
{
    public Task Handle(CreateBook command)
    {
        try
        {
            // ... create book logic ...
            Log.Books.BookCreated(logger, bookId, title);
        }
        catch (Exception ex)
        {
            Log.Books.BookCreationFailed(logger, ex, title);
            throw;
        }
    }
}

Common Patterns

Operation Flow:

• Operation starting: <Entity>Creating, <Entity>Updating, <Entity>Deleting
• Operation success: <Entity>Created, <Entity>Updated, <Entity>Deleted
• Operation failure: <Entity>CreationFailed, <Entity>UpdateFailed, etc.

Validation/Security:

• Use LogLevel.Warning for validation failures, authentication issues
• Include enough context to debug without sensitive data

Correlation:

• Include CorrelationId when starting operations for request tracing
• Include entity IDs, versions, relevant metadata

Related Skills

Prerequisites:

• Understanding of the domain you're logging for

See Also:

• /wolverine__create_operation - Uses logging in command handlers
• /wolverine__update_operation - Uses logging in update handlers
• /wolverine__delete_operation - Uses logging in delete handlers
• docs/architecture.md - System architecture and patterns
• Existing domain files in src/BookStore.ApiService/Infrastructure/Logging/