From 48b8b6148a917b6eca73d395703996360203a94d Mon Sep 17 00:00:00 2001
From: Eugene Kostrikov <eugene.kostrikov@gmail.com>
Date: Sat, 17 Feb 2024 16:33:36 +0000
Subject: [PATCH] Omit nodes without attributes or relationships from included
 list

---
 .gitignore       |  1 +
 response.go      | 27 +++++++++++++-----------
 response_test.go | 55 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 71 insertions(+), 12 deletions(-)

diff --git a/.gitignore b/.gitignore
index 19b1e1cf..b7e5cb2a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
 /examples/examples
+.idea/
diff --git a/response.go b/response.go
index b44e4e97..035c6f48 100644
--- a/response.go
+++ b/response.go
@@ -51,17 +51,16 @@ var (
 // Many Example: you could pass it, w, your http.ResponseWriter, and, models, a
 // slice of Blog struct instance pointers to be written to the response body:
 //
-//	 func ListBlogs(w http.ResponseWriter, r *http.Request) {
-//     blogs := []*Blog{}
+//		 func ListBlogs(w http.ResponseWriter, r *http.Request) {
+//	    blogs := []*Blog{}
 //
-//		 w.Header().Set("Content-Type", jsonapi.MediaType)
-//		 w.WriteHeader(http.StatusOK)
+//			 w.Header().Set("Content-Type", jsonapi.MediaType)
+//			 w.WriteHeader(http.StatusOK)
 //
-//		 if err := jsonapi.MarshalPayload(w, blogs); err != nil {
-//			 http.Error(w, err.Error(), http.StatusInternalServerError)
+//			 if err := jsonapi.MarshalPayload(w, blogs); err != nil {
+//				 http.Error(w, err.Error(), http.StatusInternalServerError)
+//			 }
 //		 }
-//	 }
-//
 func MarshalPayload(w io.Writer, models interface{}) error {
 	payload, err := Marshal(models)
 	if err != nil {
@@ -514,17 +513,21 @@ func appendIncluded(m *map[string]*Node, nodes ...*Node) {
 
 func nodeMapValues(m *map[string]*Node) []*Node {
 	mp := *m
-	nodes := make([]*Node, len(mp))
+	nodes := make([]*Node, 0)
 
-	i := 0
 	for _, n := range mp {
-		nodes[i] = n
-		i++
+		if !isNodeEmpty(n) {
+			nodes = append(nodes, n)
+		}
 	}
 
 	return nodes
 }
 
+func isNodeEmpty(n *Node) bool {
+	return (n.Attributes == nil || len(n.Attributes) == 0) && (n.Relationships == nil || len(n.Relationships) == 0)
+}
+
 func convertToSliceInterface(i *interface{}) ([]interface{}, error) {
 	vals := reflect.ValueOf(*i)
 	if vals.Kind() != reflect.Slice {
diff --git a/response_test.go b/response_test.go
index b1d5967a..aeb33a50 100644
--- a/response_test.go
+++ b/response_test.go
@@ -957,6 +957,61 @@ func TestMarshal_InvalidIntefaceArgument(t *testing.T) {
 	}
 }
 
+func TestMarshal_EmptyAttributesNotIncluded(t *testing.T) {
+	type Primary struct {
+		ID          string     `jsonapi:"primary,primary"`
+		Attr        string     `jsonapi:"attr,attr,omitempty"`
+		Secondary   *Primary   `jsonapi:"relation,secondary,omitempty"`
+		Secondaries []*Primary `jsonapi:"relation,secondaries,omitempty"`
+	}
+
+	p := &Primary{
+		ID:   "1",
+		Attr: "a",
+		Secondary: &Primary{
+			ID: "2",
+		},
+		Secondaries: []*Primary{
+			{ID: "3"},
+		},
+	}
+
+	t.Run("Single payload", func(t *testing.T) {
+		out := bytes.NewBuffer(nil)
+		if err := MarshalPayload(out, p); err != nil {
+			t.Fatal(err)
+		}
+
+		var jsonData map[string]interface{}
+		if err := json.Unmarshal(out.Bytes(), &jsonData); err != nil {
+			t.Fatal(err)
+		}
+
+		_, ok := jsonData["included"].([]interface{})
+		if ok {
+			t.Fatal("Was expecting included to be empty")
+		}
+	})
+
+	t.Run("Many payload", func(t *testing.T) {
+
+		out := bytes.NewBuffer(nil)
+		if err := MarshalPayload(out, []*Primary{p}); err != nil {
+			t.Fatal(err)
+		}
+
+		var jsonData map[string]interface{}
+		if err := json.Unmarshal(out.Bytes(), &jsonData); err != nil {
+			t.Fatal(err)
+		}
+
+		_, ok := jsonData["included"].([]interface{})
+		if ok {
+			t.Fatal("Was expecting included to be empty")
+		}
+	})
+}
+
 func testBlog() *Blog {
 	return &Blog{
 		ID:        5,