Add Model support for TreeItemSelector control source data

demos/form-control/tree-item-selector.php

@@ -50,6 +50,12 @@
 $control = $form->addControl('tree1', [Form\Control\TreeItemSelector::class, 'treeItems' => $items, 'allowMultiple' => false, 'caption' => 'Single selection:']);
 $control->set(502);
 
+$model = new File($app->db);
+$control = $form->addControl('tree2', [Form\Control\TreeItemSelector::class, 'allowMultiple' => false, 'caption' => 'Selection from tree in Atk4/Model:',
+    'parentIdField' => $model->fieldName()->parent_folder_id]);
+
+$control->setModel($model);
+
 // $control->onItem(function (int $value) {
 //    return new JsToast('Received ' . $value);
 // });
@@ -58,6 +64,7 @@
     $response = [
         'multiple' => $form->model->get('tree'),
         'single' => $form->model->get('tree1'),
+        'model' => $form->model->get('tree2'),
     ];
 
     $view = new Message('Items: ');

src/Form/Control/TreeItemSelector.php

@@ -4,6 +4,7 @@
 
 namespace Atk4\Ui\Form\Control;
 
+use Atk4\Data\Model;
 use Atk4\Ui\Form;
 use Atk4\Ui\HtmlTemplate;
 use Atk4\Ui\Js\Jquery;
@@ -39,6 +40,13 @@ class TreeItemSelector extends Form\Control
      */
     public $loaderCssName = 'atk-tree-loader';
 
+    /**
+     * The field name which includes the parent node's id.
+     *
+     * @var string
+     */
+    public $parentIdField = 'parent_id';
+
     /** @var bool Allow multiple selection or just one. */
     public $allowMultiple = true;
 
@@ -112,6 +120,46 @@ public function setTreeItems(array $treeItems)
         return $this;
     }
 
+    /**
+     * Recursive function to return sub-node for a given parent.
+     *
+     * @param $model : Model
+     * @param $nodes: array
+     * @param $parentId : int|string|null
+     *
+     * @return array|null
+     */
+    protected function addNodes(Model $model, array $nodes, $parentId = null)
+    {
+        // return an array of items with parent = $parentId
+        $result = [];
+        foreach ($nodes as $node) {
+            if ($node[$this->parentIdField] === $parentId) {
+                $newNode = [];
+                $newNode['name'] = $node[$model->titleField];
+                $newNode['id'] = $node[$model->idField];
+                $newNode['parent_id'] = $node[$this->parentIdField];
+                $newNode['nodes'] = $this->addNodes($model, $nodes, $newNode['id']);
+                $result[] = $newNode;
+            }
+        }
+
+        if (count($result) > 0) {
+            return $result;
+        }
+
+        return null;
+    }
+
+    public function setModel(Model $model): void
+    {
+        parent::setModel($model);
+
+        $nodes_array = (clone $this->model)->export();
+        $this->treeItems = $this->addNodes($model, $nodes_array);
+        unset($nodes_array);
+    }
+
     /**
      * Returns <input ...> tag.
      *