Add support to Marshal slices of nested objects

Author: brandonc

models_test.go

@@ -190,6 +190,16 @@ type Company struct {
 	FoundedAt time.Time `jsonapi:"attr,founded-at,iso8601"`
 }
 
+type CompanyOmitEmpty struct {
+	ID        string    `jsonapi:"primary,companies"`
+	Name      string    `jsonapi:"attr,name,omitempty"`
+	Boss      Employee  `jsonapi:"attr,boss,omitempty"`
+	Manager   *Employee `jsonapi:"attr,manager,omitempty"`
+	Teams     []Team    `jsonapi:"attr,teams,omitempty"`
+	People    []*People `jsonapi:"attr,people,omitempty"`
+	FoundedAt time.Time `jsonapi:"attr,founded-at,iso8601,omitempty"`
+}
+
 type People struct {
 	Name string `jsonapi:"attr,name"`
 	Age  int    `jsonapi:"attr,age"`

response.go

@@ -401,14 +401,36 @@ func visitModelNode(model interface{}, included *map[string]*Node,
 					continue
 				}
 
-				if fieldValue.Type().Kind() == reflect.Struct || (fieldValue.Type().Kind() == reflect.Pointer && fieldValue.Elem().Kind() == reflect.Struct) {
+				isStruct := fieldValue.Type().Kind() == reflect.Struct
+				isPointerToStruct := fieldValue.Type().Kind() == reflect.Pointer && fieldValue.Elem().Kind() == reflect.Struct
+				isSliceOfStruct := fieldValue.Type().Kind() == reflect.Slice && fieldValue.Type().Elem().Kind() == reflect.Struct
+				isSliceOfPointerToStruct := fieldValue.Type().Kind() == reflect.Slice && fieldValue.Type().Elem().Kind() == reflect.Pointer && fieldValue.Type().Elem().Elem().Kind() == reflect.Struct
+
+				if isSliceOfStruct || isSliceOfPointerToStruct {
+					if fieldValue.Len() == 0 && omitEmpty {
+						continue
+					}
+					// Nested slice of object attributes
+					manyNested, err := visitModelNodeRelationships(fieldValue, nil, false)
+					if err != nil {
+						er = fmt.Errorf("failed to marshal slice of nested attribute %q: %w", args[1], err)
+						break
+					}
+					nestedNodes := make([]any, len(manyNested.Data))
+					for i, n := range manyNested.Data {
+						nestedNodes[i] = n.Attributes
+					}
+					node.Attributes[args[1]] = nestedNodes
+				} else if isStruct || isPointerToStruct {
+					// Nested object attribute
 					nested, err := visitModelNode(fieldValue.Interface(), nil, false)
 					if err != nil {
 						er = fmt.Errorf("failed to marshal nested attribute %q: %w", args[1], err)
 						break
 					}
 					node.Attributes[args[1]] = nested.Attributes
 				} else {
+					// Primative attribute
 					strAttr, ok := fieldValue.Interface().(string)
 					if ok {
 						node.Attributes[args[1]] = strAttr
@@ -626,7 +648,7 @@ func visitModelNodeRelationships(models reflect.Value, included *map[string]*Nod
 
 	for i := 0; i < models.Len(); i++ {
 		model := models.Index(i)
-		if !model.IsValid() || model.IsNil() {
+		if !model.IsValid() || (model.Kind() == reflect.Pointer && model.IsNil()) {
 			return nil, ErrUnexpectedNil
 		}
 

response_test.go

@@ -694,6 +694,14 @@ func TestMarshalObjectAttribute(t *testing.T) {
 			Firstname: "Dave",
 			HiredAt:   &now,
 		},
+		Teams: []Team{
+			{Name: "Team 1"},
+			{Name: "Team-2"},
+		},
+		People: []*People{
+			{Name: "Person-1"},
+			{Name: "Person-2"},
+		},
 	}
 
 	out := bytes.NewBuffer(nil)
@@ -734,6 +742,69 @@ func TestMarshalObjectAttribute(t *testing.T) {
 	if manager["firstname"] != "Dave" {
 		t.Fatalf("Expected manager.firstname to be \"Dave\", got %v", manager)
 	}
+
+	people, ok := data.Attributes["people"].([]interface{})
+	if !ok {
+		t.Fatalf("Expected people attribute, got %v", data.Attributes)
+	}
+	if len(people) != 2 {
+		t.Fatalf("Expected 2 people, got %v", people)
+	}
+
+	teams, ok := data.Attributes["teams"].([]interface{})
+	if !ok {
+		t.Fatalf("Expected teams attribute, got %v", data.Attributes)
+	}
+	if len(teams) != 2 {
+		t.Fatalf("Expected 2 teams, got %v", teams)
+	}
+}
+
+func TestMarshalObjectAttributeWithEmptyNested(t *testing.T) {
+	testModel := &CompanyOmitEmpty{
+		ID:      "5",
+		Name:    "test",
+		Boss:    Employee{},
+		Manager: nil,
+		Teams:   []Team{},
+		People:  nil,
+	}
+
+	out := bytes.NewBuffer(nil)
+	if err := MarshalPayload(out, testModel); err != nil {
+		t.Fatal(err)
+	}
+
+	resp := new(OnePayload)
+	if err := json.NewDecoder(out).Decode(resp); err != nil {
+		t.Fatal(err)
+	}
+
+	data := resp.Data
+
+	if data.Attributes == nil {
+		t.Fatalf("Expected attributes")
+	}
+
+	_, ok := data.Attributes["boss"].(map[string]interface{})
+	if ok {
+		t.Fatalf("Expected omitted boss attribute, got %v", data.Attributes)
+	}
+
+	_, ok = data.Attributes["manager"].(map[string]interface{})
+	if ok {
+		t.Fatalf("Expected omitted manager attribute, got %v", data.Attributes)
+	}
+
+	_, ok = data.Attributes["people"].([]interface{})
+	if ok {
+		t.Fatalf("Expected omitted people attribute, got %v", data.Attributes)
+	}
+
+	_, ok = data.Attributes["teams"].([]interface{})
+	if ok {
+		t.Fatalf("Expected omitted teams attribute, got %v", data.Attributes)
+	}
 }
 
 func TestOmitsZeroTimes(t *testing.T) {