[12.x] Adds simple key transformation to Collection and Arr helper.

src/Illuminate/Collections/Arr.php

@@ -1158,6 +1158,40 @@ public static function toCssStyles($array)
         return implode(' ', $styles);
     }
 
+    /**
+     * Executes a callback that transforms each key of the array.
+     *
+     * @param  array  $array
+     * @param  callable  $callback
+     * @return array
+     */
+    public static function mapKeys(array $array, callable $callback)
+    {
+        return array_combine(array_map($callback, array_keys($array)), array_values($array));
+    }
+
+    /**
+     * Transforms each key of the array into "camelCase".
+     *
+     * @param  array  $array
+     * @return array
+     */
+    public static function mapKeysToCamel(array $array)
+    {
+        return static::mapKeys($array, [Str::class, 'camel']);
+    }
+
+    /**
+     * Transforms each key of the array into "snake_case".
+     *
+     * @param  array  $array
+     * @return array
+     */
+    public static function mapKeysToSnake(array $array)
+    {
+        return static::mapKeys($array, [Str::class, 'snake']);
+    }
+
     /**
      * Filter the array using the given callback.
      *

src/Illuminate/Collections/Collection.php

@@ -846,6 +846,19 @@ public function mapToDictionary(callable $callback)
         return new static($dictionary);
     }
 
+    /**
+     * Map each key in the collection using a callback.
+     *
+     * @template TNewKey of array-key
+     *
+     * @param  callable(TKey): TNewKey  $callback
+     * @return static<TNewKey, TValue>
+     */
+    public function mapKeys(callable $callback)
+    {
+        return new static(Arr::mapKeys($this->all(), $callback));
+    }
+
     /**
      * Run an associative map over each of the items.
      *
@@ -1742,6 +1755,21 @@ public function transform(callable $callback)
         return $this;
     }
 
+    /**
+     * Transform each key in the collection using a callback.
+     *
+     * @param  callable(TKey): TKey  $callback
+     * @return $this
+     *
+     * @phpstan-this-out static<TKey, TValue>
+     */
+    public function transformKeys(callable $callback)
+    {
+        $this->items = Arr::mapKeys($this->all(), $callback);
+
+        return $this;
+    }
+
     /**
      * Flatten a multi-dimensional associative array with dots.
      *

tests/Support/SupportArrTest.php

@@ -994,6 +994,45 @@ public function testMapNullValues()
         $this->assertEquals(['first' => 'first-taylor', 'last' => 'last-'], $mapped);
     }
 
+    public function testMapKeys()
+    {
+        $array = [100, '200', 300, '400', 500];
+
+        $array = Arr::mapKeys($array, fn($key) => $key + 1);
+
+        $this->assertSame([1 => 100, 2 => '200', 3 => 300, 4 => '400', 5 => 500], $array);
+    }
+
+    public function testMapKeysToCamel()
+    {
+        $array = [
+            1 => 'foo',
+            'foo_bar' => 'bar',
+            'cuzCux' => 'baz',
+        ];
+
+        $this->assertSame([
+            '1' => 'foo',
+            'fooBar' => 'bar',
+            'cuzCux' => 'baz',
+        ], Arr::mapKeysToCamel($array));
+    }
+
+    public function testMapKeysToSnake()
+    {
+        $array = [
+            1 => 'foo',
+            'foo_bar' => 'bar',
+            'cuzCux' => 'baz',
+        ];
+
+        $this->assertSame([
+            '1' => 'foo',
+            'foo_bar' => 'bar',
+            'cuz_cux' => 'baz',
+        ], Arr::mapKeysToSnake($array));
+    }
+
     public function testMapWithKeys()
     {
         $data = [

tests/Support/SupportCollectionTest.php

@@ -3305,6 +3305,13 @@ public function testTransform()
         $this->assertEquals(['first' => 'first-rolyat', 'last' => 'last-llewto'], $data->all());
     }
 
+    public function testTransformKeys()
+    {
+        $data = new Collection(['first' => 'taylor', 'last' => 'otwell']);
+        $data = $data->mapKeys('strtoupper');
+        $this->assertSame(['FIRST' => 'taylor', 'LAST' => 'otwell'], $data->all());
+    }
+
     #[DataProvider('collectionClassProvider')]
     public function testGroupByAttribute($collection)
     {