Marshal embedded structs and struct pointers (#16)

jsonapi_test.go

@@ -53,6 +53,8 @@ var (
 	articleAIntIDID                              = ArticleIntIDID{ID: IntID(1), Title: "A"}
 	articleBIntIDID                              = ArticleIntIDID{ID: IntID(2), Title: "B"}
 	articlesIntIDIDABPtr                         = []*ArticleIntIDID{&articleAIntIDID, &articleBIntIDID}
+	articleEmbedded                              = ArticleEmbedded{ID: "1", Title: "A", Metadata: Metadata{LastModified: time.Date(1989, 06, 15, 0, 0, 0, 0, time.UTC)}}
+	articleEmbeddedPointer                       = ArticleEmbeddedPointer{ID: "1", Title: "A", Metadata: &Metadata{LastModified: time.Date(1989, 06, 15, 0, 0, 0, 0, time.UTC)}}
 
 	// articles with optional meta
 	articleAWithMeta              = ArticleWithMeta{ID: "1", Title: "A", Meta: &ArticleMetrics{Views: 10, Reads: 4}}
@@ -86,6 +88,7 @@ var (
 	articleLinkedOnlySelfBody         = `{"data":{"id":"1","type":"articles","links":{"self":"https://example.com/articles/1"}}}`
 	articleWithResourceObjectMetaBody = `{"data":{"type":"articles","id":"1","attributes":{"title":"A"},"meta":{"count":10}}}`
 	articleAWithMetaBody              = `{"data":{"id":"1","type":"articles","attributes":{"title":"A"},"meta":{"views":10,"reads":4}}}`
+	articleEmbeddedBody               = `{"data":{"type":"articles","id":"1","attributes":{"title":"A","lastModified":"1989-06-15T00:00:00Z"}}}`
 
 	// articles with relationships bodies
 	articleRelatedNoOmitEmptyBody               = `{"data":{"id":"1","type":"articles","attributes":{"title":"A"},"relationships":{"author":{"data":null},"comments":{"data":[]}}}}`
@@ -327,3 +330,21 @@ type ArticleDoubleID struct {
 	Title   string `jsonapi:"attribute" json:"title"`
 	OtherID string `jsonapi:"primary,article"`
 }
+
+type Metadata struct {
+	LastModified time.Time `jsonapi:"attribute" json:"lastModified"`
+}
+
+type ArticleEmbedded struct {
+	Metadata
+
+	ID    string `jsonapi:"primary,articles"`
+	Title string `jsonapi:"attribute" json:"title"`
+}
+
+type ArticleEmbeddedPointer struct {
+	*Metadata
+
+	ID    string `jsonapi:"primary,articles"`
+	Title string `jsonapi:"attribute" json:"title"`
+}

marshal.go

@@ -298,16 +298,16 @@ func makeResourceObject(v any, vt reflect.Type, m *Marshaler, isRelationship boo
 		Relationships: make(map[string]*document, 0),
 	}
 
-	rv := derefValue(reflect.ValueOf(v))
-	rt := reflect.TypeOf(rv.Interface())
+	// get fields from embedded structs
+	fields := getFlattenedFields(v)
 
 	var foundPrimary bool
-	for i := 0; i < rv.NumField(); i++ {
+	for _, field := range fields {
 		// for each field in the struct we'll parse the jsonapi struct tag
 		// this will determine where it goes in the resource object (e.g. id,type,attributes,...)
 
-		f := rv.Field(i)
-		ft := rt.Field(i)
+		f := field.v
+		ft := field.f
 
 		tag, err := parseJSONAPITag(ft)
 		if err != nil {
@@ -434,6 +434,35 @@ func makeResourceObject(v any, vt reflect.Type, m *Marshaler, isRelationship boo
 	return ro, nil
 }
 
+func getFlattenedFields(iface interface{}) []struct {
+	v reflect.Value
+	f reflect.StructField
+} {
+	rv := derefValue(reflect.ValueOf(iface))
+	rt := reflect.TypeOf(rv.Interface())
+
+	fields := make([]struct {
+		v reflect.Value
+		f reflect.StructField
+	}, 0)
+
+	for i := 0; i < rv.NumField(); i++ {
+		v := rv.Field(i)
+		f := rt.Field(i)
+
+		if f.Anonymous && (v.Kind() == reflect.Struct || v.Kind() == reflect.Pointer) {
+			fields = append(fields, getFlattenedFields(v.Interface())...)
+		} else {
+			fields = append(fields, struct {
+				v reflect.Value
+				f reflect.StructField
+			}{v, f})
+		}
+	}
+
+	return fields
+}
+
 func addOptionalDocumentFields(d *document, m *Marshaler) error {
 	// optionally include Document.meta (may be nil, which will be omitted)
 	if err := checkMeta(m.meta); err != nil {

marshal_test.go

@@ -185,6 +185,16 @@ func TestMarshal(t *testing.T) {
 			given:       &articleWithoutResourceObjectMeta,
 			expect:      articleABody,
 			expectError: nil,
+		}, {
+			description: "ArticleEmbedded",
+			given:       &articleEmbedded,
+			expect:      articleEmbeddedBody,
+			expectError: nil,
+		}, {
+			description: "ArticleEmbeddedPointer",
+			given:       &articleEmbeddedPointer,
+			expect:      articleEmbeddedBody,
+			expectError: nil,
 		}, {
 			description: "Error simple",
 			given:       errorsSimpleStruct,

unmarshal_test.go

@@ -129,6 +129,26 @@ func TestUnmarshal(t *testing.T) {
 			},
 			expect:      &articleAWithMeta,
 			expectError: nil,
+		}, {
+			description: "ArticleEmbedded",
+			given:       articleEmbeddedBody,
+			do: func(body []byte) (any, error) {
+				var a ArticleEmbedded
+				err := Unmarshal(body, &a)
+				return &a, err
+			},
+			expect:      &articleEmbedded,
+			expectError: nil,
+		}, {
+			description: "ArticleEmbeddedPointer",
+			given:       articleEmbeddedBody,
+			do: func(body []byte) (any, error) {
+				var a ArticleEmbeddedPointer
+				err := Unmarshal(body, &a)
+				return &a, err
+			},
+			expect:      &articleEmbeddedPointer,
+			expectError: nil,
 		}, {
 			description: "nil",
 			given:       "",