fixed issue with indexBy and array valued relations

framework/db/ActiveRelationTrait.php

@@ -62,6 +62,7 @@ trait ActiveRelationTrait
      */
     public $inverseOf;
 
+
     /**
      * Clones internal objects.
      */
@@ -106,7 +107,6 @@ trait ActiveRelationTrait
         if ($callable !== null) {
             call_user_func($callable, $relation);
         }
-
         return $this;
     }
 
@@ -133,7 +133,6 @@ trait ActiveRelationTrait
     public function inverseOf($relationName)
     {
         $this->inverseOf = $relationName;
-
         return $this;
     }
 
@@ -244,7 +243,14 @@ trait ActiveRelationTrait
                     $value = [];
                     foreach ($keys as $key) {
                         if (isset($buckets[$key])) {
-                            $value = array_merge($value, $buckets[$key]);
+                            if ($this->indexBy !== null) {
+                                // if indexBy is set, array_merge will cause renumbering of numeric array
+                                foreach($buckets[$key] as $bucketKey => $bucketValue) {
+                                    $value[$bucketKey] = $bucketValue;
+                                }
+                            } else {
+                                $value = array_merge($value, $buckets[$key]);
+                            }
                         }
                     }
                 } else {

tests/unit/data/ar/Order.php

@@ -45,6 +45,12 @@ class Order extends ActiveRecord
             })->orderBy('item.id');
     }
 
+    public function getItemsIndexed()
+    {
+        return $this->hasMany(Item::className(), ['id' => 'item_id'])
+            ->via('orderItems')->indexBy('id');
+    }
+
     public function getItemsWithNullFK()
     {
         return $this->hasMany(Item::className(), ['id' => 'item_id'])

tests/unit/data/ar/elasticsearch/Order.php

@@ -48,6 +48,12 @@ class Order extends ActiveRecord
             ->via('orderItems')->orderBy('id');
     }
 
+    public function getItemsIndexed()
+    {
+        return $this->hasMany(Item::className(), ['id' => 'item_id'])
+            ->via('orderItems')->indexBy('id');
+    }
+
     public function getItemsWithNullFK()
     {
         return $this->hasMany(Item::className(), ['id' => 'item_id'])

tests/unit/data/ar/redis/Order.php

@@ -27,6 +27,12 @@ class Order extends ActiveRecord
             });
     }
 
+    public function getItemsIndexed()
+    {
+        return $this->hasMany(Item::className(), ['id' => 'item_id'])
+            ->via('orderItems')->indexBy('id');
+    }
+
     public function getItemsInOrder1()
     {
         return $this->hasMany(Item::className(), ['id' => 'item_id'])

tests/unit/framework/ar/ActiveRecordTestTrait.php

@@ -1064,4 +1064,29 @@ trait ActiveRecordTestTrait
         $customers = $customerClass::find()->where(['IN', 'id', []])->all();
         $this->assertEquals(0, count($customers));
     }
+
+    public function testFindEagerIndexBy()
+    {
+        /* @var $this TestCase|ActiveRecordTestTrait */
+
+        /* @var $orderClass \yii\db\ActiveRecordInterface */
+        $orderClass = $this->getOrderClass();
+
+        /* @var $order Order */
+        $order = $orderClass::find()->with('itemsIndexed')->where(['id' => 1])->one();
+        $this->assertTrue($order->isRelationPopulated('itemsIndexed'));
+        $items = $order->itemsIndexed;
+        $this->assertEquals(2, count($items));
+        $this->assertTrue(isset($items[1]));
+        $this->assertTrue(isset($items[2]));
+
+        /* @var $order Order */
+        $order = $orderClass::find()->with('itemsIndexed')->where(['id' => 2])->one();
+        $this->assertTrue($order->isRelationPopulated('itemsIndexed'));
+        $items = $order->itemsIndexed;
+        $this->assertEquals(3, count($items));
+        $this->assertTrue(isset($items[3]));
+        $this->assertTrue(isset($items[4]));
+        $this->assertTrue(isset($items[5]));
+    }
 }