Update a field in database via model

This loads the specified model , which you want update .

public function execute()
    {
        $post = $this->$postFactory->create();
        $id_post_update = 19; //Example

        $postUpdate = $post->load($id_post_update);
        $postUpdate->setSlidePosition(2);
        $postUpdate->setId(22);
        $postUpdate->save();
    }