From f5c5711fc651e07be20a7567038255620d66f063 Mon Sep 17 00:00:00 2001
From: Kenta Mori <zoncoen@gmail.com>
Date: Wed, 13 Sep 2023 17:17:47 +0900
Subject: [PATCH] fix: skip encoding an inline field if it is null (#386)

---
 encode.go      |  4 ++++
 encode_test.go | 24 ++++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/encode.go b/encode.go
index 7d8d81e..3b9b298 100644
--- a/encode.go
+++ b/encode.go
@@ -823,6 +823,10 @@ func (e *Encoder) encodeStruct(ctx context.Context, value reflect.Value, column
 			}
 			mapNode, ok := value.(ast.MapNode)
 			if !ok {
+				// if an inline field is null, skip encoding it
+				if _, ok := value.(*ast.NullNode); ok {
+					continue
+				}
 				return nil, xerrors.Errorf("inline value is must be map or struct type")
 			}
 			mapIter := mapNode.MapRange()
diff --git a/encode_test.go b/encode_test.go
index 74b1aa5..e872c61 100644
--- a/encode_test.go
+++ b/encode_test.go
@@ -980,6 +980,30 @@ c: true
 	}
 }
 
+func TestEncoder_InlineNil(t *testing.T) {
+	type base struct {
+		A int
+		B string
+	}
+	var buf bytes.Buffer
+	enc := yaml.NewEncoder(&buf)
+	if err := enc.Encode(struct {
+		*base `yaml:",inline"`
+		C     bool
+	}{
+		C: true,
+	}); err != nil {
+		t.Fatalf("%+v", err)
+	}
+	expect := `
+c: true
+`
+	actual := "\n" + buf.String()
+	if expect != actual {
+		t.Fatalf("inline marshal error: expect=[%s] actual=[%s]", expect, actual)
+	}
+}
+
 func TestEncoder_Flow(t *testing.T) {
 	var buf bytes.Buffer
 	enc := yaml.NewEncoder(&buf, yaml.Flow(true))