Audit logging: who did what, to which record, from where, and when.
Different from the application log on purpose. A log line is for whoever is debugging; an audit entry is a record somebody may be asked about a year later — "who deleted that account?" — and it therefore lives in the database, beside the data it describes, rather than in a file that rotates.
App::new().plugin(Audit::new(db.clone()))
// and in the registry the CLI generates:
registry.extend(rustlavel_audit::migrations());
Then, from anywhere with a request:
use rustlavel_audit::AuditExt;
req.audit("users.deleted")
.on("User", user.id)
.describe(format!("{} deleted {}", actor, user.name))
.with("email", Json::from(user.email.as_str()))
.save()
.await?;
What the builder does not let you do is forget the context. The actor, the address and the user agent are read off the request rather than passed in, because an entry that says "someone updated the settings" answers nothing, and a caller in a hurry is exactly who writes that entry.