From 4c25f5818dce00a61b190c99f4f8d517d31e2a45 Mon Sep 17 00:00:00 2001
From: Vitaliy <160263432+vitalivo@users.noreply.github.com>
Date: Sat, 12 Sep 2026 16:05:32 +0300
Subject: [PATCH] Preserve slice elements when setting an indexed value

---
 accessors.go      | 11 +++++++++--
 accessors_test.go | 25 +++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/accessors.go b/accessors.go
index 72f1d1c..a8038d7 100644
--- a/accessors.go
+++ b/accessors.go
@@ -134,7 +134,7 @@ func access(current interface{}, selector string, value interface{}, isSet bool)
 	switch current.(type) {
 	case map[string]interface{}:
 		curMSI := current.(map[string]interface{})
-		if nextSel == "" && isSet {
+		if nextSel == "" && isSet && len(indexes) == 0 {
 			curMSI[thisSel] = value
 			return nil
 		}
@@ -161,12 +161,19 @@ func access(current interface{}, selector string, value interface{}, isSet bool)
 			index := indexes[num]
 			indexes = indexes[:num]
 			if array, ok := interSlice(current); ok {
-				if index < len(array) {
+				if index >= 0 && index < len(array) {
+					if isSet && nextSel == "" && num == 0 {
+						array[index] = value
+						return nil
+					}
 					current = array[index]
 				} else {
 					current = nil
 					break
 				}
+			} else {
+				current = nil
+				break
 			}
 		}
 	}
diff --git a/accessors_test.go b/accessors_test.go
index 7b6f1a7..0c1d049 100644
--- a/accessors_test.go
+++ b/accessors_test.go
@@ -256,3 +256,28 @@ func TestAccessorsNested(t *testing.T) {
 	value = d.Get("values[1][2].names[0]").String()
 	assert.Equal(t, "Captain", value)
 }
+
+func TestGetIndexOnNonSlice(t *testing.T) {
+	for _, value := range []interface{}{42, "text", objx.Map{"name": "value"}, nil} {
+		m := objx.Map{"value": value}
+		assert.Nil(t, m.Get("value[0]").Data())
+		assert.Nil(t, m.Get("value[0].name").Data())
+	}
+	m := objx.Map{"value": []interface{}{42}}
+	assert.Nil(t, m.Get("value[0][0]").Data())
+	assert.Equal(t, 42, m.Get("value[0]").Data())
+}
+
+func TestSetIndexPreservesSlice(t *testing.T) {
+	m := objx.Map{"names": []interface{}{"Tyler", "Sam"}}
+	m.Set("names[0]", "Mat")
+	assert.Equal(t, []interface{}{"Mat", "Sam"}, m["names"])
+	m.Set("names[2]", "outside")
+	assert.Equal(t, []interface{}{"Mat", "Sam"}, m["names"])
+	m.Set("names[1]", nil)
+	assert.Equal(t, []interface{}{"Mat", nil}, m["names"])
+
+	m = objx.Map{"nested": []interface{}{[]interface{}{"first", "second"}}}
+	m.Set("nested[0][1]", "changed")
+	assert.Equal(t, []interface{}{[]interface{}{"first", "changed"}}, m["nested"])
+}