ILoggerTCategoryName

ILoggerTCategoryName is the generic form of the logging interface used in the Microsoft.Extensions.Logging framework. It is defined as ILogger<TCategoryName> and inherits from ILogger, with the category name automatically derived from the type parameter TCategoryName. By default, the category represents the full type name, including its namespace, which helps organize and filter log output by source.

Usage typically involves dependency injection. In a class named OrderService, for example, a constructor can request ILogger<OrderService> and store it for later use. This approach ties the log category to the class type, making logs easy to trace. For instance, you would log messages with methods such as LogInformation, LogWarning, or LogError, all of which are available through the inherited ILogger interface and its extension methods.

The typed logger provides the same logging capabilities as a non-generic ILogger, including Log, BeginScope, and the standard log level methods (Information, Warning, Error, Critical). The difference is that the category name is fixed at compile time to the TCategoryName type, which improves clarity and enables precise category-based filtering.

Configuration and filtering can target the specific category name derived from TCategoryName. For example, in appsettings.json you can set a LogLevel for a particular namespace and class, such as "MyApp.Services.OrderService", while leaving other categories unaffected. If dynamic category names are needed, an alternative is to create a non-generic logger via ILoggerFactory.CreateLogger(string categoryName).

See also: Microsoft.Extensions.Logging, ILogger, ILoggerFactory, Dependency Injection, AppSettings configuration.