Implement mapByKey

src/Illuminate/Collections/Arr.php

@@ -643,6 +643,35 @@ public static function mapWithKeys(array $array, callable $callback)
         return $result;
     }
 
+    /**
+     * Run an associative map over each of the item's values filtered by their key.
+     *
+     * The callback should return the same resultset with the modified values of the given keys.
+     *
+     * @param  array  $array
+     * @param  string|array  $keys
+     * @param  callable  $callback
+     * @return array
+     */
+    public static function mapByKey(array $array, $keys, callable $callback)
+    {
+        $result = [];
+
+        foreach ($array as $parentKey => $row) {
+            foreach ($row as $key => $value) {
+                if (! in_array($key, (array) $keys, true)) {
+                    $result[$parentKey][$key] = $value;
+
+                    continue;
+                }
+
+                $result[$parentKey][$key] = $callback($value, $key, $row);
+            }
+        }
+
+        return $result;
+    }
+
     /**
      * Run a map over each nested chunk of items.
      *

src/Illuminate/Collections/Collection.php

@@ -843,6 +843,20 @@ public function mapWithKeys(callable $callback)
         return new static(Arr::mapWithKeys($this->items, $callback));
     }
 
+    /**
+     * Run an associative map over each of the item's values filtered by their key.
+     *
+     * The callback should return the same resultset with the modified values of the given keys.
+     *
+     * @param  string|array  $keys
+     * @param  callable  $callback
+     * @return static
+     */
+    public function mapByKey($keys, callable $callback)
+    {
+        return new static(Arr::mapByKey($this->items, $keys, $callback));
+    }
+
     /**
      * Merge the collection with the given items.
      *

src/Illuminate/Collections/LazyCollection.php

@@ -843,6 +843,20 @@ public function mapWithKeys(callable $callback)
         });
     }
 
+    /**
+     * Run an associative map over each of the item's values filtered by their key.
+     *
+     * The callback should return the same resultset with the modified values of the given keys.
+     *
+     * @param  string|array  $keys
+     * @param  callable  $callback
+     * @return static
+     */
+    public function mapByKey($keys, callable $callback)
+    {
+        return $this->passthru('mapByKey', func_get_args());
+    }
+
     /**
      * Merge the collection with the given items.
      *

tests/Support/SupportArrTest.php

@@ -6,6 +6,8 @@
 use Illuminate\Support\Arr;
 use Illuminate\Support\Carbon;
 use Illuminate\Support\Collection;
+use Illuminate\Support\Number;
+use Illuminate\Support\Str;
 use InvalidArgumentException;
 use PHPUnit\Framework\TestCase;
 use stdClass;
@@ -804,6 +806,60 @@ public function testMapWithKeys()
         );
     }
 
+    public function testMapByKey()
+    {
+        $invoices = [
+            ['recipient' => 'Dries', 'currency' => 'USD', 'amount' => 1],
+            ['recipient' => 'Taylor', 'currency' => 'USD', 'amount' => 25.67],
+            ['recipient' => 'Nuno', 'currency' => 'EUR', 'amount' => 123987],
+        ];
+
+        $invoices = Arr::mapByKey($invoices, 'amount', function ($value, $key, $row) {
+            return Number::currency($value, $row['currency']);
+        });
+
+        $this->assertEquals(
+            [
+                ['recipient' => 'Dries', 'currency' => 'USD', 'amount' => '$1.00'],
+                ['recipient' => 'Taylor', 'currency' => 'USD', 'amount' => '$25.67'],
+                ['recipient' => 'Nuno', 'currency' => 'EUR', 'amount' => '€123,987.00'],
+            ],
+            $invoices
+        );
+
+        $posts = [
+            ['title' => 'Hello World', 'body' => '# Hello World', 'preview' => 'Test *post*'],
+            ['title' => 'New Release', 'body' => '**New Release**', 'preview' => '**Release notes**'],
+        ];
+
+        $posts = Arr::mapByKey($posts, ['body', 'preview'], fn ($value) => Str::markdown($value));
+
+        $this->assertEquals(
+            [
+                ['title' => 'Hello World', 'body' => "<h1>Hello World</h1>\n", 'preview' => "<p>Test <em>post</em></p>\n"],
+                ['title' => 'New Release', 'body' => "<p><strong>New Release</strong></p>\n", 'preview' => "<p><strong>Release notes</strong></p>\n"],
+            ],
+            $posts
+        );
+
+        $data = [
+            ['foo' => 'Dries', 'bar' => 'Joe', 'baz' => 'Jess'],
+            ['foo' => 'Taylor', 'baz' => 'James'],
+            ['bar' => 'Nuno'],
+        ];
+
+        $data = Arr::mapByKey($data, ['bar', 'baz'], fn ($value) => Str::lower($value));
+
+        $this->assertEquals(
+            [
+                ['foo' => 'Dries', 'bar' => 'joe', 'baz' => 'jess'],
+                ['foo' => 'Taylor', 'baz' => 'james'],
+                ['bar' => 'nuno'],
+            ],
+            $data
+        );
+    }
+
     public function testMapByReference()
     {
         $data = ['first' => 'taylor', 'last' => 'otwell'];

tests/Support/SupportCollectionTest.php

@@ -3053,6 +3053,27 @@ public function testMapWithKeysCallbackKey($collection)
         );
     }
 
+    #[DataProvider('collectionClassProvider')]
+    public function testMapByKey($collection)
+    {
+        $data = new $collection([
+            ['foo' => 'Dries', 'bar' => 'Joe', 'baz' => 'Jess'],
+            ['foo' => 'Taylor', 'baz' => 'James'],
+            ['bar' => 'Nuno'],
+        ]);
+
+        $data = $data->mapByKey(['bar', 'baz'], fn ($value) => Str::lower($value));
+
+        $this->assertEquals(
+            [
+                ['foo' => 'Dries', 'bar' => 'joe', 'baz' => 'jess'],
+                ['foo' => 'Taylor', 'baz' => 'james'],
+                ['bar' => 'nuno'],
+            ],
+            $data->all()
+        );
+    }
+
     #[DataProvider('collectionClassProvider')]
     public function testMapInto($collection)
     {