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There are several objects in WordPress that we use all the time, namely $post, $comment and categories/tags. If you’re like me though, you never remember everything that’s in there, or the names of the values you want.

This cheat sheet will be a reference which you (and I) can refer to the next time you’re using one of the WordPress objects.

Quick Primer on Using Objects

If you haven’t used objects before or aren’t familiar with the syntax, there are 3 simple things to know:

1 – Objects store details about a particular “thing”, e.g. the $post object will store details like the date and author of the post.

2 – To access a value, you use the following syntax:

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$object->property

e.g. If we wanted to print out the post’s ID, we’d write:

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echo $post->ID;

3 – If you need to see everything that’s in your object, use the following to get a nicely laid out view of it:

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<pre>
<?php print_r($object); ?>
</pr>

(Add in the extra ‘e’ in </pre>. I’ve just taken it out so my syntax highlighter plugin still works!)

The $post Object

Let’s start with the one you will use the most. In every WordPress loop, a global $post variable is set containing everything about that post/page.

This is a global variable, so you can access it outside of the loop. To do that, add this to your PHP before you use it:

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global $post;

Array
 (
       [0] => 61
       [1] => 57
 )

For simplicity sake, I’ve referred to certain values as being used for Pages only. Of course, if you’ve defined a custom post type that uses those attributes (e.g. post_parent), then it will be used there too.

Tag and Category Objects

Each individual category or tag can be represented as an object. We’ll start with a quick look at the 3 main functions for getting tag and category objects.

The get_term_by() function is fantastic for finding a single tag or category. You can tell it to search by name, ID, or slug, and whether it’s a tag (post_tag), category or custom taxonomy you’re after, e.g.

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$term = get_term_by('slug', 'featured', 'post_tag');

To get all the tags on a post, you would use the get_the_tags() function, e.g.

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$tags = get_the_tags();
foreach($tags as $term) {
    echo "$term->name | "; 
}

And similarly, to get all of the categories on a post, we’ll use get_the_category():

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$tags = get_the_category();
foreach($tags as $term) {
    echo "$term->name | "; 
}

For backwards compatibility, the $category object returned stores many of these values under other names as well, e.g. term_id and cat_ID both return the category ID.

To make things easier on yourself though, forget the category-specific versions and use the ones above instead. That way, you won’t have to remember the difference between the tag and category versions.

The $comment Object

Last of all, we’re going to look at the $comment object. During your comments loop, you can access this object to get specific information about the comment.

And that finishes up our look at the main WordPress objects. There are functions for getting directly at a lot of this information, but at times, it’s far easier to simply take what you need from these objects without worrying about all the different function names.

If you’d like to see examples of how these can be put to use, let me know in the comments and I’ll share some of the ways I’ve used them! And of course, feel free to share your own!