rename to ContextFieldExtractor and allow multiple extractors

exp/zapslog/handler.go

@@ -32,17 +32,17 @@ import (
 	"go.uber.org/zap/zapcore"
 )
 
-// ContextExtractor can be used to extract fields from a context.
-type ContextExtractor func(ctx context.Context) []zapcore.Field
+// ContextFieldExtractor can be used to extract a field from a context.
+type ContextFieldExtractor func(ctx context.Context) []zapcore.Field
 
 // Handler implements the slog.Handler by writing to a zap Core.
 type Handler struct {
-	core             zapcore.Core
-	name             string // logger name
-	addCaller        bool
-	addStackAt       slog.Level
-	callerSkip       int
-	contextExtractor ContextExtractor
+	core                   zapcore.Core
+	name                   string // logger name
+	addCaller              bool
+	addStackAt             slog.Level
+	callerSkip             int
+	contextFieldExtractors ContextFieldExtractor
 }
 
 // NewHandler builds a [Handler] that writes to the supplied [zapcore.Core]
@@ -162,8 +162,8 @@ func (h *Handler) Handle(ctx context.Context, record slog.Record) error {
 	}
 
 	var contextFields []zapcore.Field
-	if h.contextExtractor != nil {
-		contextFields = h.contextExtractor(ctx)
+	for _, extractor := range h.contextFieldExtractors {
+		contextFields = append(contextFields, extractor(ctx)...)
 	}
 
 	fields := make([]zapcore.Field, 0, record.NumAttrs()+len(contextFields))

exp/zapslog/handler_test.go

@@ -194,12 +194,12 @@ func TestAttrKinds(t *testing.T) {
 		entry.ContextMap())
 }
 
-func TestContextExtractor(t *testing.T) {
+func TestContextFieldExtractor(t *testing.T) {
 	key := testContextKey("testkey")
 	fac, logs := observer.New(zapcore.DebugLevel)
 	ctx := context.WithValue(context.Background(), key, "testvalue")
 
-	sl := slog.New(NewHandler(fac, WithContextExtractor(func(ctx context.Context) []zapcore.Field {
+	sl := slog.New(NewHandler(fac, WithContextFieldExtractor(func(ctx context.Context) []zapcore.Field {
 		v := ctx.Value(key).(string)
 		return []zapcore.Field{zap.String("testkey", v)}
 	})))

exp/zapslog/options.go

@@ -71,9 +71,9 @@ func AddStacktraceAt(lvl slog.Level) Option {
 	})
 }
 
-// .WithContextExtractor configures the Logger to extract fields from the context,
-func WithContextExtractor(extractor ContextExtractor) Option {
+// .WithContextFieldExtractor configures the Logger to extract fields from the context,
+func WithContextFieldExtractors(extractors ...ContextFieldExtractor) Option {
 	return optionFunc(func(log *Handler) {
-		log.contextExtractor = extractor
+		log.contextFieldExtractors = append(log.contextFieldExtractors, extractors...)
 	})
 }