Add itemprop:image Microdata to WordPress Featured Image

This code adds structured data from Schema.org to your WordPress thumbnails (a.ka. featured images). It will add the attribute itemprop:image inside the <img> tag of the featured image. This simple method doesn’t require you to add anything to your functions.php file. You just pass the parameter along in the “the_post_thumbnail” template tag. This is done directly on any template file of your WordPress child theme. Very easy!

Find your thumbnail template tag. If it’s not specifying a size, then it looks like this:

<?php the_post_thumbnail(); ?>

If it is specifying a size, then it will have the size name inside the parenthesis, like so:

<?php the_post_thumbnail( 'size' ); ?>

where ‘size’ will usually be either ‘thumbnail’, ‘post-thumbnail’, ‘medium’, ‘large’, or ‘full’.

Before we begin

Setting an attribute for “the_post_thumbnail” is done as the second parameter, so if your thumbnail template tag looks like the first example above (with empty parenthesis), please add ‘post-thumbnail’ inside the parenthesis. This is because ‘post-thumbnail’ is the default value for the first parameter of the_post_thumbnail. So, make it look like this:

<?php the_post_thumbnail( 'post-thumbnail' ); ?>

Now the code

To add the structured data “image” property (itemprop:image), you add it as the second parameter inside the parenthesis. So, the line above becomes this:

<?php the_post_thumbnail( 'post-thumbnail', array( 'itemprop' => 'image' ) ); ?>

Note that ‘post-thumbnail’ in the line above can vary depending on the size of image your theme uses.

Here are some examples of how the ‘post-thumbnail’ part will vary depending on the size of image your theme uses. The following are 5 different examples.

<?php the_post_thumbnail( 'thumbnail', array( 'itemprop' => 'image' ) ); ?>

<?php the_post_thumbnail( 'medium', array( 'itemprop' => 'image' ) ); ?>

<?php the_post_thumbnail( 'large', array( 'itemprop' => 'image' ) ); ?>

<?php the_post_thumbnail( 'full', array( 'itemprop' => 'image' ) ); ?>

<?php the_post_thumbnail( 'custom_size', array( 'itemprop' => 'image' ) ); ?>