Forms 使用映射列表以symfony（推进）形式保存时无法执行insert语句

在doSave（）函数的表单中，我试图保存文章类别（它是树中的一个节点），然后将文章分配给这个类别（多对多关系）。 我在

$this->saveWaArticleNewsCategoryMapList（$con）中遇到错误行。（项目基于symfony 1.4.16）将文章分配到现有类别时没有错误。

public function doSave($con = null) {

$scope = $this->getValue('tree_scope');
$toEdit = $this->getObject();
if ($toEdit->isNew()) {
    $node = new ArticleCategory();
    $node->setBrandId($this->getValue('brand_id'));
    $node->setName($this->getValue('name'));
    $node->setTreeScope($scope);

    $root = ArticleCategoryQuery::create()->findRoot($scope);
    if ($root == null) {
        $root = new ArticleCategory();
        $root->setName('Root');
        $root->setTreeScopeIdValue($scope);
        $root->makeRoot();
        $root->save($con);

        $node->insertAsLastChildOf($root);
        $node->save($con);
        return;
    }
    $parent = ArticleCategoryQuery::create()->findPk($this->getValue('parent_id'));
    $node->insertAsLastChildOf($parent);
} else {
    $node = ArticleCategoryQuery::create()->findOneByArticleCategoryId($toEdit->getArticleCategoryId());
    $node->setBrandId($this->getValue('brand_id'));
    $node->setName($this->getValue('name'));
    if ($toEdit->getParent()->getArticleCategoryId() != $this->getValue('parent_id')) {
        $parent = ArticleCategoryQuery::create()->findPk($this->getValue('parent_id'));
        $node->moveToLastChildOf($parent);
    }
}
$node->save($con);
$this->saveArticleNewsCategoryMapList($con); <--Error
$this->saveArticleHelpCategoryMapList($con);
}

更新对象中的
ArticleCategoryId
解决了以下问题：

$node->save($con);
$this->getObject()->setArticleCategoryId($node->getArticleCategoryId());
...

$node->save($con);
$this->getObject()->setArticleCategoryId($node->getArticleCategoryId());
...