Fix Multiline expression calc when there is no row (#2306)

Author: mvorisek

demos/form-control/multiline-containsmany-single.php

@@ -7,7 +7,6 @@
 use Atk4\Ui\App;
 use Atk4\Ui\Form;
 use Atk4\Ui\Js\JsToast;
-use Doctrine\DBAL\Platforms\MySQLPlatform;
 
 /** @var App $app */
 require_once __DIR__ . '/../init-app.php';
@@ -20,19 +19,5 @@
     $form->entity->save();
     $form->entity->setNull($form->entity->idField);
 
-    // fix Behat for MySQL with unordered/normalized JSON
-    $data = $form->entity->get();
-    if ($form->getApp()->db->getDatabasePlatform() instanceof MySQLPlatform) {
-        assert($form->entity instanceof MultilineDelivery);
-        $itemKey = $form->entity->fieldName()->item;
-        if ($data[$itemKey] !== null) {
-            uksort($data[$itemKey], static function ($a, $b) use ($form) {
-                $fieldNamesOrder = array_flip(array_values(array_map(static fn ($v) => $v->getPersistenceName(), $form->entity->item->getFields())));
-
-                return $fieldNamesOrder[$a] <=> $fieldNamesOrder[$b];
-            });
-        }
-    }
-
-    return new JsToast($form->getApp()->encodeJson($data));
+    return new JsToast($form->getApp()->encodeJson($form->entity->get()));
 });

src/Form/Control/Multiline.php

@@ -830,7 +830,24 @@ private function getExpressionValues(Model $entity): array
             return [];
         }
 
-        $dummyModel = new Model($entity->getModel()->getPersistence(), ['table' => $entity->getModel()->table, 'idField' => false]);
+        $dummyModel = new Model($entity->getModel()->getPersistence(), [
+            'table' => new class($entity->getModel()->getPersistence()) extends Model {
+                public $table = '';
+
+                #[\Override]
+                public function action(string $mode, array $args = [])
+                {
+                    assert($mode === 'select');
+                    assert($args === []);
+
+                    $query = Persistence\Sql::assertInstanceOf($this->getPersistence())->dsql();
+                    $query->field($query->expr('[]', [1]));
+
+                    return $query;
+                }
+            },
+            'idField' => false,
+        ]);
 
         $createExprFromValueFx = static function ($v) use ($dummyModel): Persistence\Sql\Expression {
             if (is_int($v)) {
@@ -853,7 +870,6 @@ private function getExpressionValues(Model $entity): array
                 'actual' => $field->actual,
             ]);
         }
-        $dummyModel->setLimit(1); // TODO must work with empty table, no table should be used
         $values = $dummyModel->loadOne()->get();
         unset($values[$entity->idField]);