Adding extra image field to any DCA say tl_article

I have added a new field for article teaser Image like below in my custom module-> MyMod/dca/tl_article:

Code:

---

/* article teaser image */
$GLOBALS['TL_DCA']['tl_article']['fields']['atImage'] = array
(
                        'label'                => &$GLOBALS['TL_LANG']['tl_article']['atImage'],
                        'exclude'                => true,
                        'inputType'                => 'fileTree',
                        'eval'                        => array('filesOnly'=>true, 'fieldType'=>'radio', 'tl_class'=>'clr'),
                        'sql'                    => "varchar(255) NOT NULL default ''"
);

// Augment the pallette
$GLOBALS['TL_DCA']['tl_article']['palettes']['default'] = str_replace('teaser;', 'teaser, atImage;', $GLOBALS['TL_DCA']['tl_article']['palettes']['default']);

---

In the template mod_artcle I wanted to out put this image. But doing <?php echo $this->atImage; ?> gives only the ID of an Image.
At the moment I am doing like:

Code:

---

        <?php
                $objFile = \FilesModel::findByPk($this->atImage);
                echo $objFile->path;
        ?>

---

inside the template (mod_article), which I am not satisfied. I think there is a better way of setting up template variables with real image path. Can some one suggest please.

That's the correct way to do it. If you would like to resize an image, then you would need to use

Code:

---

<?php \Image::get($objFile->path, 100, 100, 'center_center'); ?>

---

You would be able to deliver the path to the template only if you override the ModuleArticle class.

Thank your for the answer, and your blog helped me a lot too.
At the moment the correct answer is not so satisfying because I've to put lots of php code in Template file. So I think overriding the Module class might be a better option. Can you tell me a best practice how to override a core class.