Moved key serialization from data provider to data viewers.

framework/yii/data/ActiveDataProvider.php

@@ -138,9 +138,9 @@ class ActiveDataProvider extends BaseDataProvider
 				foreach ($models as $model) {
 					$kk = [];
 					foreach ($pks as $pk) {
-						$kk[] = $model[$pk];
+						$kk[$pk] = $model[$pk];
 					}
-					$keys[] = json_encode($kk);
+					$keys[] = $kk;
 				}
 			}
 			return $keys;

framework/yii/grid/GridView.php

@@ -373,7 +373,7 @@ class GridView extends BaseListView
 		} else {
 			$options = $this->rowOptions;
 		}
-		$options['data-key'] = $key;
+		$options['data-key'] = is_array($key) ? json_encode($key) : $key;
 		return Html::tag('tr', implode('', $cells), $options);
 	}
 

framework/yii/widgets/ListView.php

@@ -88,7 +88,7 @@ class ListView extends BaseListView
 		$options = $this->itemOptions;
 		$tag = ArrayHelper::remove($options, 'tag', 'div');
 		if ($tag !== false) {
-			$options['data-key'] = $key;
+			$options['data-key'] = is_array($key) ? json_encode($key) : $key;
 			return Html::tag($tag, $content, $options);
 		} else {
 			return $content;