How to insert data properly in Joomla article with content plugin?

Question

I have created a content plugin which adds extra field on Joomla default article editor window and everything working as expected.

But the problem is with existing/old articles created before installing the plugin.

Here what I added on template/html/com_content/article/default.php

$checkPlugin = JPluginHelper::getPlugin('content', 'customdata');

<?php if ($checkPlugin && !empty($attributes->subtitle) : ?>
    <div><?php echo $attributes->subtitle; ?></div>
<?php endif; ?>

It's working perfectly when I add new article, but with existing articles showing below error:

Notice: Undefined property: stdClass::$subtitle in .......\html\com_content\article\default.php on line 41

What I'm doing wrong?

Answer 1

Try using isset() to check if the object property is actualy set, like so:

<?php if (!empty($attributes->subtitle) && isset($attributes->subtitle)) : ?>
    <div><?php echo $attributes->subtitle; ?></div>
<?php endif; ?>