[5.5] Add buildToDictionary Method

src/Illuminate/Database/Eloquent/Relations/HasOneOrMany.php

@@ -162,18 +162,11 @@ protected function getRelationValue(array $dictionary, $key, $type)
      */
     protected function buildDictionary(Collection $results)
     {
-        $dictionary = [];
-
         $foreign = $this->getForeignKeyName();
 
-        // First we will create a dictionary of models keyed by the foreign key of the
-        // relationship as this will allow us to quickly access all of the related
-        // models without having to do nested looping which will be quite slow.
-        foreach ($results as $result) {
-            $dictionary[$result->{$foreign}][] = $result;
-        }
-
-        return $dictionary;
+        return $results->mapToDictionary(function ($result) use ($foreign) {
+            return [$result->{$foreign} => $result];
+        })->all();
     }
 
     /**

src/Illuminate/Support/Collection.php

@@ -851,22 +851,37 @@ public function mapSpread(callable $callback)
     }
 
     /**
-     * Run a grouping map over the items.
+     * Run a dictionary map over the items.
      *
      * The callback should return an associative array with a single key/value pair.
      *
      * @param  callable  $callback
      * @return static
      */
-    public function mapToGroups(callable $callback)
+    public function mapToDictionary(callable $callback)
     {
-        $groups = $this->map($callback)->reduce(function ($groups, $pair) {
+        $dictionary = $this->map($callback)->reduce(function ($groups, $pair) {
             $groups[key($pair)][] = reset($pair);
 
             return $groups;
         }, []);
 
-        return (new static($groups))->map([$this, 'make']);
+        return new static($dictionary);
+    }
+
+    /**
+     * Run a grouping map over the items.
+     *
+     * The callback should return an associative array with a single key/value pair.
+     *
+     * @param  callable  $callback
+     * @return static
+     */
+    public function mapToGroups(callable $callback)
+    {
+        $groups = $this->mapToDictionary($callback);
+
+        return $groups->map([$this, 'make']);
     }
 
     /**

tests/Support/SupportCollectionTest.php

@@ -1257,6 +1257,35 @@ public function testFlatMap()
         $this->assertEquals(['programming', 'basketball', 'music', 'powerlifting'], $data->all());
     }
 
+    public function testMapToDictionary()
+    {
+        $data = new Collection([
+            ['id' => 1, 'name' => 'A'],
+            ['id' => 2, 'name' => 'B'],
+            ['id' => 3, 'name' => 'C'],
+            ['id' => 4, 'name' => 'B'],
+        ]);
+
+        $groups = $data->mapToDictionary(function ($item, $key) {
+            return [$item['name'] => $item['id']];
+        });
+
+        $this->assertInstanceOf(Collection::class, $groups);
+        $this->assertEquals(['A' => [1], 'B' => [2, 4], 'C' => [3]], $groups->toArray());
+        $this->assertInternalType('array', $groups['A']);
+    }
+
+    public function testMapToDictionaryWithNumericKeys()
+    {
+        $data = new Collection([1, 2, 3, 2, 1]);
+
+        $groups = $data->mapToDictionary(function ($item, $key) {
+            return [$item => $key];
+        });
+
+        $this->assertEquals([1 => [0, 4], 2 => [1, 3], 3 => [2]], $groups->toArray());
+    }
+
     public function testMapToGroups()
     {
         $data = new Collection([