From d0d91814845efbe2e4b55176f171cacfbcc784ad Mon Sep 17 00:00:00 2001
From: Maximilian Pachl <m@ximilian.info>
Date: Sat, 14 Oct 2017 11:31:44 +0200
Subject: [PATCH] properly handle embedded (anonymous) fields

---
 sheriff.go      | 65 ++++++++++++++++++++++++++++++++-----------------
 sheriff_test.go | 61 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 104 insertions(+), 22 deletions(-)

diff --git a/sheriff.go b/sheriff.go
index 95ecfc6..843101a 100644
--- a/sheriff.go
+++ b/sheriff.go
@@ -80,32 +80,43 @@ func Marshal(options *Options, data interface{}) (interface{}, error) {
 			continue
 		}
 
-		if checkGroups {
-			groups := strings.Split(field.Tag.Get("groups"), ",")
-
-			shouldShow := listContains(groups, options.Groups)
-			if !shouldShow || len(groups) == 0 {
-				continue
-			}
+		// if there is an anonymous field which is a struct
+		// we want the childs exposed at the toplevel to be
+		// consistent with the embedded json marshaller
+		if val.Kind() == reflect.Ptr {
+			val = val.Elem()
 		}
 
-		if since := field.Tag.Get("since"); since != "" {
-			sinceVersion, err := version.NewVersion(since)
-			if err != nil {
-				return nil, err
-			}
-			if options.ApiVersion.LessThan(sinceVersion) {
-				continue
+		// we can skip the group checkif if the field is a composition field
+		isEmbeddedField := field.Anonymous && val.Kind() == reflect.Struct
+		if !isEmbeddedField {
+			if checkGroups {
+				groups := strings.Split(field.Tag.Get("groups"), ",")
+
+				shouldShow := listContains(groups, options.Groups)
+				if !shouldShow || len(groups) == 0 {
+					continue
+				}
 			}
-		}
 
-		if until := field.Tag.Get("until"); until != "" {
-			untilVersion, err := version.NewVersion(until)
-			if err != nil {
-				return nil, err
+			if since := field.Tag.Get("since"); since != "" {
+				sinceVersion, err := version.NewVersion(since)
+				if err != nil {
+					return nil, err
+				}
+				if options.ApiVersion.LessThan(sinceVersion) {
+					continue
+				}
 			}
-			if options.ApiVersion.GreaterThan(untilVersion) {
-				continue
+
+			if until := field.Tag.Get("until"); until != "" {
+				untilVersion, err := version.NewVersion(until)
+				if err != nil {
+					return nil, err
+				}
+				if options.ApiVersion.GreaterThan(untilVersion) {
+					continue
+				}
 			}
 		}
 
@@ -113,7 +124,17 @@ func Marshal(options *Options, data interface{}) (interface{}, error) {
 		if err != nil {
 			return nil, err
 		}
-		dest[jsonTag] = v
+
+		// when a composition field we want to bring the child
+		// nodes to the top
+		nestedVal, ok := v.(map[string]interface{})
+		if isEmbeddedField && ok {
+			for key, value := range nestedVal {
+				dest[key] = value
+			}
+		} else {
+			dest[jsonTag] = v
+		}
 	}
 
 	return dest, nil
diff --git a/sheriff_test.go b/sheriff_test.go
index 7fbda78..3cd3d5c 100644
--- a/sheriff_test.go
+++ b/sheriff_test.go
@@ -403,3 +403,64 @@ func TestMarshal_EmptyMap(t *testing.T) {
 
 	assert.Equal(t, string(expected), string(actual))
 }
+
+type TestMarshal_Embedded struct {
+	Foo string `json:"foo" groups:"test"`
+}
+
+type TestMarshal_EmbeddedParent struct {
+	*TestMarshal_Embedded
+	Bar string `json:"bar" groups:"test"`
+}
+
+func TestMarshal_EmbeddedField(t *testing.T) {
+	v := TestMarshal_EmbeddedParent{
+		&TestMarshal_Embedded{"Hello"},
+		"World",
+	}
+	o := &Options{Groups: []string{"test"}}
+
+	actualMap, err := Marshal(o, v)
+	assert.NoError(t, err)
+
+	actual, err := json.Marshal(actualMap)
+	assert.NoError(t, err)
+
+	expected, err := json.Marshal(map[string]interface{}{
+		"bar": "World",
+		"foo": "Hello",
+	})
+	assert.NoError(t, err)
+
+	assert.Equal(t, string(expected), string(actual))
+}
+
+type TestMarshal_EmbeddedEmpty struct {
+	Foo string
+}
+
+type TestMarshal_EmbeddedParentEmpty struct {
+	*TestMarshal_EmbeddedEmpty
+	Bar string `json:"bar" groups:"test"`
+}
+
+func TestMarshal_EmbeddedFieldEmpty(t *testing.T) {
+	v := TestMarshal_EmbeddedParentEmpty{
+		&TestMarshal_EmbeddedEmpty{"Hello"},
+		"World",
+	}
+	o := &Options{Groups: []string{"test"}}
+
+	actualMap, err := Marshal(o, v)
+	assert.NoError(t, err)
+
+	actual, err := json.Marshal(actualMap)
+	assert.NoError(t, err)
+
+	expected, err := json.Marshal(map[string]interface{}{
+		"bar": "World",
+	})
+	assert.NoError(t, err)
+
+	assert.Equal(t, string(expected), string(actual))
+}