metadata: add MustGet func

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

logger/options.go

@@ -106,7 +106,9 @@ func WithAddFields(fields ...interface{}) Option {
 					}
 				}
 			}
-			o.Fields = append(o.Fields, fields...)
+			if len(fields) > 0 {
+				o.Fields = append(o.Fields, fields...)
+			}
 		} else {
 			o.Fields = append(o.Fields, fields...)
 		}

logger/slog/slog.go

@@ -142,6 +142,7 @@ func (s *slogLogger) Fields(fields ...interface{}) logger.Logger {
 	s.mu.RUnlock()
 
 	l := &slogLogger{opts: options}
+	logger.WithAddFields(fields...)(&l.opts)
 
 	if len(options.ContextAttrFuncs) == 0 {
 		options.ContextAttrFuncs = logger.DefaultContextAttrFuncs

logger/slog/slog_test.go

@@ -15,7 +15,29 @@ import (
 	"go.unistack.org/micro/v3/metadata"
 )
 
-func TestWithDuplicate(t *testing.T) {
+func TestWithFields(t *testing.T) {
+	ctx := context.TODO()
+	buf := bytes.NewBuffer(nil)
+	l := NewLogger(logger.WithLevel(logger.InfoLevel), logger.WithOutput(buf),
+		WithHandlerFunc(slog.NewTextHandler),
+		logger.WithDedupKeys(true),
+	)
+	if err := l.Init(logger.WithFields("key1", "val1")); err != nil {
+		t.Fatal(err)
+	}
+
+	l.Info(ctx, "msg1")
+
+	l = l.Fields("key1", "val2")
+
+	l.Info(ctx, "msg2")
+
+	if !bytes.Contains(buf.Bytes(), []byte(`msg=msg2 key1=val1`)) {
+		t.Fatalf("logger error not works, buf contains: %s", buf.Bytes())
+	}
+}
+
+func TestWithDedupKeysWithAddFields(t *testing.T) {
 	ctx := context.TODO()
 	buf := bytes.NewBuffer(nil)
 	l := NewLogger(logger.WithLevel(logger.InfoLevel), logger.WithOutput(buf),

metadata/context.go

@@ -11,6 +11,34 @@ type (
 	mdKey         struct{}
 )
 
+// MustIncomingContext returns metadata from incoming ctx
+// returned metadata shoud not be modified or race condition happens.
+// If metadata not exists panics.
+func MustIncomingContext(ctx context.Context) Metadata {
+	if ctx == nil {
+		panic("missing metadata")
+	}
+	md, ok := ctx.Value(mdIncomingKey{}).(*rawMetadata)
+	if !ok {
+		panic("missing metadata")
+	}
+	return md.md
+}
+
+// MustOutgoingContext returns metadata from outgoing ctx
+// returned metadata shoud not be modified or race condition happens.
+// If metadata not exists panics.
+func MustOutgoingContext(ctx context.Context) Metadata {
+	if ctx == nil {
+		panic("missing metadata")
+	}
+	md, ok := ctx.Value(mdOutgoingKey{}).(*rawMetadata)
+	if !ok {
+		panic("missing metadata")
+	}
+	return md.md
+}
+
 // FromIncomingContext returns metadata from incoming ctx
 // returned metadata shoud not be modified or race condition happens
 func FromIncomingContext(ctx context.Context) (Metadata, bool) {

metadata/metadata.go

@@ -67,6 +67,22 @@ func (md Metadata) Iterator() *Iterator {
 	return iter
 }
 
+func (md Metadata) MustGet(key string) string {
+	// fast path
+	val, ok := md[key]
+	if !ok {
+		// slow path
+		val, ok = md[textproto.CanonicalMIMEHeaderKey(key)]
+		if !ok {
+			val, ok = md[strings.ToLower(key)]
+		}
+	}
+	if !ok {
+		panic("missing metadata key")
+	}
+	return val
+}
+
 // Get returns value from metadata by key
 func (md Metadata) Get(key string) (string, bool) {
 	// fast path