otelzap: Implement Reflect method

bridges/otelzap/encoder.go

@@ -4,6 +4,7 @@
 package otelzap // import "go.opentelemetry.io/contrib/bridges/otelzap"
 
 import (
+	"encoding/json"
 	"time"
 
 	"go.uber.org/zap/zapcore"
@@ -19,7 +20,8 @@ var (
 // objectEncoder implements zapcore.ObjectEncoder.
 // It encodes given fields to OTel key-values.
 type objectEncoder struct {
-	kv []log.KeyValue
+	kv         []log.KeyValue
+	reflectval log.Value
 }
 
 // nolint:unused
@@ -93,11 +95,23 @@ func (m *objectEncoder) AddUint64(k string, v uint64) {
 		})
 }
 
-// TODO.
+// AddReflected converts all non-primitive type to JSON string.
 func (m *objectEncoder) AddReflected(k string, v interface{}) error {
+	enc := json.NewEncoder(m)
+	if err := enc.Encode(v); err != nil {
+		return err
+	}
+	m.AddString(k, m.reflectval.AsString())
 	return nil
 }
 
+// Implements io.Writer to which json encoder writes to.
+// Used by [AddReflected].
+func (m *objectEncoder) Write(p []byte) (n int, err error) {
+	m.reflectval = log.StringValue(string(p))
+	return len(p), nil
+}
+
 // OpenNamespace opens an isolated namespace where all subsequent fields will
 // be added.
 func (m *objectEncoder) OpenNamespace(k string) {
@@ -179,7 +193,15 @@ func (a *arrayEncoder) AppendObject(v zapcore.ObjectMarshaler) error {
 
 // TODO.
 func (a *arrayEncoder) AppendReflected(v interface{}) error {
-	return nil
+	enc := json.NewEncoder(a)
+	return enc.Encode(v)
+}
+
+// Implements io.Writer to which json encoder writes to.
+// Used by [AppendReflected].
+func (a *arrayEncoder) Write(p []byte) (n int, err error) {
+	a.elems = append(a.elems, log.StringValue(string(p)))
+	return len(p), nil
 }
 
 func (a *arrayEncoder) AppendByteString(v []byte) {

bridges/otelzap/encoder_test.go

@@ -65,6 +65,13 @@ func TestObjectEncoder(t *testing.T) {
 			},
 			expected: []interface{}{wantTurducken, wantTurducken},
 		},
+		{
+			desc: "AddReflected",
+			f: func(e zapcore.ObjectEncoder) {
+				assert.NoError(t, e.AddReflected("k", map[string]interface{}{"foo": 5}), "Expected AddReflected to succeed.")
+			},
+			expected: "{\"foo\":5}\n",
+		},
 		{
 			desc:     "AddBinary",
 			f:        func(e zapcore.ObjectEncoder) { e.AddBinary("k", []byte("foo")) },
@@ -207,6 +214,13 @@ func TestArrayEncoder(t *testing.T) {
 			},
 			expected: []interface{}{true, false},
 		},
+		{
+			desc: "AppendReflected",
+			f: func(e zapcore.ArrayEncoder) {
+				assert.NoError(t, e.AppendReflected(map[string]interface{}{"foo": 5}))
+			},
+			expected: "{\"foo\":5}\n",
+		},
 		{"AppendBool", func(e zapcore.ArrayEncoder) { e.AppendBool(true) }, true},
 		{"AppendByteString", func(e zapcore.ArrayEncoder) { e.AppendByteString([]byte("foo")) }, "foo"},
 		{"AppendFloat64", func(e zapcore.ArrayEncoder) { e.AppendFloat64(3.14) }, 3.14},