support nested pointers

scan.go

@@ -45,12 +45,21 @@ func parseSlice(srcVal reflect.Value, destVal reflect.Value) error {
 }
 
 func parseMap(srcVal reflect.Value, destVal reflect.Value) error {
-	if destVal.Kind() != reflect.Struct {
-		return fmt.Errorf("cannot assign map to %s", destVal.Type())
-	}
-
+	destKind := destVal.Kind()
 	destType := destVal.Type()
 
+	if destKind == reflect.Ptr {
+		if destVal.IsNil() {
+			newDest := reflect.New(destType.Elem())
+			destVal.Set(newDest)
+		}
+
+		destVal = destVal.Elem()
+		destType = destVal.Type()
+	} else if destKind != reflect.Struct {
+		return fmt.Errorf("cannot assign map to %s", destType)
+	}
+
 	for i := 0; i < destType.NumField(); i++ {
 		field := destType.Field(i)
 		tag := field.Tag.Get("db")
@@ -78,6 +87,10 @@ func parseMap(srcVal reflect.Value, destVal reflect.Value) error {
 }
 
 func parseValue(srcVal reflect.Value, destVal reflect.Value) error {
+	if !srcVal.IsValid() {
+		return nil
+	}
+
 	if !srcVal.Type().AssignableTo(destVal.Type()) {
 		if destVal.Kind() == reflect.Int && srcVal.Kind() == reflect.Float64 {
 			destVal.SetInt(int64(srcVal.Float()))

scan_test.go

@@ -17,6 +17,11 @@ type nestedTestStruct struct {
 	Test  testStruct
 }
 
+type nestedTestStructPtr struct {
+	Title string
+	Test  *testStruct
+}
+
 func Test_scan(t *testing.T) {
 	t.Run("scan single map to struct", func(t *testing.T) {
 		m := map[string]any{
@@ -165,4 +170,80 @@ func Test_scan(t *testing.T) {
 			},
 		}, s)
 	})
+	t.Run("scan single map to nested struct with pointer", func(t *testing.T) {
+		m := map[string]any{
+			"title": "hello",
+			"test": map[string]any{
+				"text": "world",
+			},
+		}
+
+		var s nestedTestStructPtr
+		err := scan(m, &s)
+		assert.NoError(t, err)
+		assert.Equal(t, nestedTestStructPtr{
+			Title: "hello",
+			Test: &testStruct{
+				Text: "world",
+			},
+		}, s)
+	})
+	t.Run("scan multiple maps to nested with pointer", func(t *testing.T) {
+		m := []map[string]any{
+			{
+				"title": "hello",
+			},
+			{
+				"test": map[string]any{
+					"text": "world",
+				},
+			},
+		}
+
+		var s []nestedTestStructPtr
+		err := scan(m, &s)
+		assert.NoError(t, err)
+		assert.Equal(t, []nestedTestStructPtr{
+			{
+				Title: "hello",
+			},
+			{
+				Test: &testStruct{
+					Text: "world",
+				},
+			},
+		}, s)
+	})
+	t.Run("scan single map to nested struct with tag and pointer", func(t *testing.T) {
+		m := map[string]any{
+			"title": "hello",
+			"test": map[string]any{
+				"created_at": 123,
+			},
+		}
+
+		var s nestedTestStructPtr
+		err := scan(m, &s)
+		assert.NoError(t, err)
+		assert.Equal(t, nestedTestStructPtr{
+			Title: "hello",
+			Test: &testStruct{
+				CreatedAt: 123,
+			},
+		}, s)
+	})
+	t.Run("scan nested nil struct to pointer", func(t *testing.T) {
+		m := map[string]any{
+			"title": "hello",
+			"test":  nil,
+		}
+
+		var s nestedTestStructPtr
+		err := scan(m, &s)
+		assert.NoError(t, err)
+		assert.Equal(t, nestedTestStructPtr{
+			Title: "hello",
+			Test:  nil,
+		}, s)
+	})
 }