Blog / Standard Library

slog.Group

July 6, 2026

The one Attr constructor not yet covered:

func Group

func Group(key string, args ...any) Attr

Group returns an Attr for a Group Value. The first argument is the key; the remaining arguments are converted to Attrs as in Logger.Log.

Use Group to collect several key-value pairs under a single key on a log line, or as the result of LogValue in order to log a single value as multiple Attrs.

Groups are conceptually simple. They’re how we nest log attributes under a common key, as we can see in the inline example:

logger.Info("finished",
		slog.Group("req",
			slog.String("method", r.Method),
			slog.String("url", r.URL.String())),
		slog.Int("status", http.StatusOK),
		slog.Duration("duration", time.Second))

For the default TextHandler, groups are logged with the full key path in dot-separated notation:

level=INFO msg=finished req.method=GET req.url=localhost status=200 duration=1s

For the JSONHandler, they’re logged as inline JSON objects:

{"level":"INFO","msg":"finished","req":{"method":"GET","url":"localhost"},"status":200,"duration":1000000000}
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