Handle empty pointers to complex structs in metadata.Add

v2/metadata.go

@@ -52,7 +52,7 @@ func (meta MetaData) AddStruct(tab string, obj interface{}) {
 		meta[tab] = content
 	} else {
 		// Wasn't a struct
-		meta.Add("Extra data", tab, obj)
+		meta.Add("Extra data", tab, val)
 	}
 
 }
@@ -84,32 +84,38 @@ func (s sanitizer) Sanitize(data interface{}) interface{} {
 	// Sanitizers are passed by value, so we can modify s and it only affects
 	// s.Seen for nested calls.
 	s.Seen = append(s.Seen, data)
+	t := reflect.TypeOf(data)
+	v := reflect.ValueOf(data)
+
+	if t == nil {
+		return "<nil>"
+	}
+
+	// Handle nil pointers and interfaces specifically
+	if t.Kind() == reflect.Interface || t.Kind() == reflect.Ptr {
+		if v.IsNil() {
+			return "<nil>"
+		}
+	}
 
 	// Handle certain well known interfaces and types
-	switch data := data.(type) {
+	switch dataT := data.(type) {
 	case error:
-		return data.Error()
+		return dataT.Error()
 
 	case time.Time:
-		return data.Format(time.RFC3339Nano)
+		return dataT.Format(time.RFC3339Nano)
 
 	case fmt.Stringer:
 		// This also covers time.Duration
-		return data.String()
+		return dataT.String()
 
 	case encoding.TextMarshaler:
-		if b, err := data.MarshalText(); err == nil {
+		if b, err := dataT.MarshalText(); err == nil {
 			return string(b)
 		}
 	}
 
-	t := reflect.TypeOf(data)
-	v := reflect.ValueOf(data)
-
-	if t == nil {
-		return "<nil>"
-	}
-
 	switch t.Kind() {
 	case reflect.Bool,
 		reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
@@ -121,9 +127,6 @@ func (s sanitizer) Sanitize(data interface{}) interface{} {
 		return data
 
 	case reflect.Interface, reflect.Ptr:
-		if v.IsNil() {
-			return "<nil>"
-		}
 		return s.Sanitize(v.Elem().Interface())
 
 	case reflect.Array, reflect.Slice:

v2/metadata_test.go

@@ -34,6 +34,12 @@ func (_textMarshaller) MarshalText() ([]byte, error) {
 	return []byte("marshalled text"), nil
 }
 
+type _testStringer struct{}
+
+func (s _testStringer) String() string {
+	return "something"
+}
+
 var account = _account{}
 var notifier = New(Configuration{})
 
@@ -77,6 +83,23 @@ func TestMetaDataAdd(t *testing.T) {
 	}
 }
 
+func TestMetadataAddPointer(t *testing.T) {
+	var pointer *_testStringer
+	md := MetaData{}
+	md.AddStruct("emptypointer", pointer)
+	fullPointer := &_testStringer{}
+	md.AddStruct("fullpointer", fullPointer)
+
+	if !reflect.DeepEqual(md, MetaData{
+		"Extra data": {
+			"emptypointer": "<nil>",
+			"fullpointer":  "something",
+		},
+	}) {
+		t.Errorf("metadata.AddStruct didn't work: %#v", md)
+	}
+}
+
 func TestMetaDataUpdate(t *testing.T) {
 
 	m := MetaData{