From 9d60cddc775281a47b277a7b3c52573e4596b681 Mon Sep 17 00:00:00 2001
From: khushijain21 <khushi.jain@elastic.co>
Date: Sat, 2 Nov 2024 16:58:46 +0530
Subject: [PATCH 1/4] Do not throw error if alterfunc does not change the key

---
 mapstr/mapstr.go      | 18 +++++++++++-------
 mapstr/mapstr_test.go | 16 ++++++++++++++++
 2 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/mapstr/mapstr.go b/mapstr/mapstr.go
index 9d92b71..ea77d29 100644
--- a/mapstr/mapstr.go
+++ b/mapstr/mapstr.go
@@ -218,12 +218,16 @@ func (m M) AlterPath(path string, mode TraversalMode, alterFunc AlterFunc) (err
 		if newKey == "" {
 			return fmt.Errorf("replacement key for %q cannot be empty", key)
 		}
-		_, exists := level[newKey]
-		if exists {
-			return fmt.Errorf("replacement key %q already exists: %w", newKey, ErrKeyCollision)
+
+		// if altered key is equal to the original key, skip below delete/put func
+		if newKey != key {
+			_, exists := level[newKey]
+			if exists {
+				return fmt.Errorf("replacement key %q already exists: %w", newKey, ErrKeyCollision)
+			}
+			delete(level, key)
+			level[newKey] = val
 		}
-		delete(level, key)
-		level[newKey] = val
 
 		return nil
 	})
@@ -271,7 +275,7 @@ func (m M) Traverse(path string, mode TraversalMode, visitor TraversalVisitor) (
 
 	for i, segment := range segments {
 		if !found {
-			return ErrKeyNotFound
+			return fmt.Errorf("could not fetch value for key: %s, Error: %w ", path, ErrKeyNotFound)
 		}
 		found = false
 
@@ -316,7 +320,7 @@ func (m M) Traverse(path string, mode TraversalMode, visitor TraversalVisitor) (
 	}
 
 	if !found {
-		return ErrKeyNotFound
+		return fmt.Errorf("could not fetch value for key: %s, Error: %w", path, ErrKeyNotFound)
 	}
 
 	return nil
diff --git a/mapstr/mapstr_test.go b/mapstr/mapstr_test.go
index 2d3a791..65af644 100644
--- a/mapstr/mapstr_test.go
+++ b/mapstr/mapstr_test.go
@@ -1264,6 +1264,22 @@ func TestAlterPath(t *testing.T) {
 				},
 			},
 		},
+		{
+			name:      "alters keys on second level with case-insensitive matching",
+			from:      "level1_field1.key",
+			mode:      CaseInsensitiveMode,
+			alterFunc: lower,
+			m: M{
+				"level1_field1": M{
+					"Key": "value1",
+				},
+			},
+			exp: M{
+				"level1_field1": M{
+					"key": "value1",
+				},
+			},
+		},
 		{
 			name:      "alters keys on all nested levels with case-insensitive matching",
 			from:      "level1_field1.level2_field1.level3_field1",

From 9e9ebbb2556c4af6966037eea99e5bf1bbe7ac32 Mon Sep 17 00:00:00 2001
From: khushijain21 <khushi.jain@elastic.co>
Date: Sat, 2 Nov 2024 17:03:41 +0530
Subject: [PATCH 2/4] test case explanation

---
 mapstr/mapstr_test.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mapstr/mapstr_test.go b/mapstr/mapstr_test.go
index 65af644..f0020ca 100644
--- a/mapstr/mapstr_test.go
+++ b/mapstr/mapstr_test.go
@@ -1275,7 +1275,7 @@ func TestAlterPath(t *testing.T) {
 				},
 			},
 			exp: M{
-				"level1_field1": M{
+				"level1_field1": M{ //first level is unchanged - already in lowercase
 					"key": "value1",
 				},
 			},

From ae9efea4c30388ec8b6a0f19ad4ecced4160fb5b Mon Sep 17 00:00:00 2001
From: Khushi Jain <khushi.jain@elastic.co>
Date: Mon, 4 Nov 2024 14:57:19 +0530
Subject: [PATCH 3/4] Update mapstr/mapstr_test.go

Co-authored-by: Denis <denis@rdner.de>
---
 mapstr/mapstr_test.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mapstr/mapstr_test.go b/mapstr/mapstr_test.go
index f0020ca..8fbbf5d 100644
--- a/mapstr/mapstr_test.go
+++ b/mapstr/mapstr_test.go
@@ -1265,7 +1265,7 @@ func TestAlterPath(t *testing.T) {
 			},
 		},
 		{
-			name:      "alters keys on second level with case-insensitive matching",
+			name:      "does not return an error if alterFunc returns the key unchanged",
 			from:      "level1_field1.key",
 			mode:      CaseInsensitiveMode,
 			alterFunc: lower,

From b0f2d618476aa3fda4284b7c25257006eaafd9e8 Mon Sep 17 00:00:00 2001
From: khushijain21 <khushi.jain@elastic.co>
Date: Mon, 4 Nov 2024 15:06:06 +0530
Subject: [PATCH 4/4] update

---
 mapstr/mapstr.go | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/mapstr/mapstr.go b/mapstr/mapstr.go
index ea77d29..b3e16a1 100644
--- a/mapstr/mapstr.go
+++ b/mapstr/mapstr.go
@@ -220,14 +220,16 @@ func (m M) AlterPath(path string, mode TraversalMode, alterFunc AlterFunc) (err
 		}
 
 		// if altered key is equal to the original key, skip below delete/put func
-		if newKey != key {
-			_, exists := level[newKey]
-			if exists {
-				return fmt.Errorf("replacement key %q already exists: %w", newKey, ErrKeyCollision)
-			}
-			delete(level, key)
-			level[newKey] = val
+		if newKey == key {
+			return nil
+		}
+
+		_, exists := level[newKey]
+		if exists {
+			return fmt.Errorf("replacement key %q already exists: %w", newKey, ErrKeyCollision)
 		}
+		delete(level, key)
+		level[newKey] = val
 
 		return nil
 	})