Updated `yii\grid\DataColumn::getHeaderCellLabel()` to extract attribute label from the `filterModel` of Grid

Closes #9950

framework/CHANGELOG.md

@@ -5,7 +5,8 @@ Yii Framework 2 Change Log
 2.0.9 under development
 -----------------------
 
-- Enh #4146: Added `yii\data\ArrayDataProvider::$modelClass` property to specify a model used to provide column labels even when data array is empty (PowerGamer1)
+- Enh #11490: Added `yii\data\ArrayDataProvider::$modelClass` property to specify a model used to provide column labels even when data array is empty (PowerGamer1)
+- Bug #9950: Updated `yii\grid\DataColumn::getHeaderCellLabel()` to extract attribute label from the `filterModel` of Grid (silverfire)
 - Enh #11428: Speedup SQL query in `yii\db\oci\Schema::findColumns()` (SSiwek)
 - Enh #11414: Files specified as `null` in `yii\web\AssetBundle` won't be registered (Razzwan)
 - Enh #11432: Added HTTP status 421 "Misdirected Request" to list of statuses in `yii\web\Response` (dasmfm)

framework/grid/DataColumn.php

@@ -148,6 +148,8 @@ class DataColumn extends Column
                 /* @var $model Model */
                 $model = new $provider->modelClass;
                 $label = $model->getAttributeLabel($this->attribute);
+            } else if ($this->grid->filterModel !== null && $this->grid->filterModel instanceof Model) {
+                $label = $this->grid->filterModel->getAttributeLabel($this->attribute);
             } else {
                 $models = $provider->getModels();
                 if (($model = reset($models)) instanceof Model) {

tests/framework/grid/DataColumnTest.php

@@ -20,7 +20,7 @@ class DataColumnTest extends \yiiunit\TestCase
         $this->mockApplication();
     }
 
-    public function testColumnLabelsOnEmptyProvider()
+    public function testColumnLabelsOnEmptyArrayProvider()
     {
         $grid = new GridView([
             'dataProvider' => new ArrayDataProvider([
@@ -41,4 +41,26 @@ class DataColumnTest extends \yiiunit\TestCase
 
         $this->assertEquals(['Customer', 'Invoice Total'], $labels);
     }
+
+    public function testColumnLabelsOnEmptyArrayProviderWithFilterModel()
+    {
+        $grid = new GridView([
+            'dataProvider' => new ArrayDataProvider([
+                'allModels' => [],
+                'totalCount' => 0,
+            ]),
+            'columns' => ['customer_id', 'total'],
+            'filterModel' => new Order
+        ]);
+
+        $labels = [];
+        foreach ($grid->columns as $column) {
+            $method = new \ReflectionMethod($column, 'getHeaderCellLabel');
+            $method->setAccessible(true);
+            $labels[] = $method->invoke($column);
+            $method->setAccessible(false);
+        }
+
+        $this->assertEquals(['Customer', 'Invoice Total'], $labels);
+    }
 }