Boldly Go

A focused look at the slog.Group function in Go's standard library logging package. It explains how Group creates an Attr that nests multiple key-value pairs under a single key. The TextHandler outputs grouped attributes in dot-separated notation (e.g., req.method=GET), while the JSONHandler outputs them as nested JSON objects.

slog.Group

<p>The nice part is Group composes with logger.WithGroup — call WithGroup(“req”) once on a request-scoped logger and every downstream attr nests under req. automatically, no repeating the key. One gotcha worth knowing: attrs you attach with .With before switching into a group stay at the top level, so the order you layer loggers in actually changes the output shape.</p>
