One challenge in WordPress is saving meta data on a taxonomy. For instance imagine you want to save additional data on a category or tag. Currently there is no wp_termmeta database table to store taxonomy meta data. In this tutorial I’m going to show you how to save a single ID against every category in WordPress. I’m going to save that meta data (the ID in this case) as a single array of options in the WordPress options table.
First we need to add a form field to the Edit Category screen. To do this we’ll use the edit_category_form_fields action hook available in WordPress:
<?php
add_action ( 'edit_category_form_fields', 'tme_cat_featured');
function tme_cat_featured( $tag ) {
//check for existing featured ID
$cat_featured = get_option( 'category_featured' );
$featured_id = '';
if ( is_array( $cat_featured ) && array_key_exists( $tag->term_id, $cat_featured ) ) {
$featured_id = $cat_featured[$tag->term_id] ;
}
?>
<tr class="form-field">
<th scope="row" valign="top"><label for="category_featured"><?php _e('Featured Post ID') ?></label></th>
<td>
<input type="text" name="category_featured" id="category_featured" size="3" style="width:5%;" value="<?php echo $featured_id; ?>"><br />
<span class="description">The post ID that will be the featured post when viewing this category.</span>
</td>
</tr>
<?php
}
?>
The above code will add a single text field (Featured Post ID) to the Edit Category screen as shown in the screenshot below:
Now that we’ve added a text field to our Edit Category page we need to save the input to our option array. To capture the ID when a category is updated we’ll use the edited_category action hook like so:
<?php
add_action ( 'edited_category', 'tme_save_featured');
function tme_save_featured( $term_id ) {
if ( isset( $_POST['category_featured'] ) ) {
//load existing category featured option
$current_featured = get_option( 'category_featured' );
//set featured post ID to proper category ID in options array
$current_featured[$term_id] = intval( $_POST['category_featured'] );
//save the option array
update_option( 'category_featured', $current_featured );
}
}
?>
As you can see we are saving the Category ID and Featured Post ID as a single associative array option value in WordPress named category_featured. As you add Featured Post ID values to each of your categories they will be added to this array and saved in WordPress. One thing to consider when using this method is scalability. If you plan on storing thousands of meta data values for your taxonomies this isn’t the method for you.
I packaged this example into a stand alone plugin so you can easily install on your WordPress website and test it out: Download the Taxonomy Meta Data plugin example.
hi,
awesome tip ! thanx a lot for sharing this ! i was looking for something like that for ages
never thougth saving the taxonomies meta datas to wp_options table in association with the term id…
as i need this kind of feature in many projects (till now i was doing horrible twiks to achive that sort of things…) i’m just playing with it right now
so i thought i should share with your other readers (for sure you’re already aware of what i’m going to say
that to clean up the data base on terms deletion you may use something like that :
http://pastie.org/1027996
Thanxs again !
Séb.
Hi Brad,
I’m trying to do something like this for taxonomy terms… but with more meta data… do you have any ideas how to pull that one off? I’d like to add at least 4 new fields and an image for each taxonomy term…
So how would we actually USE the values that we store like this, in say, a WordPress post or page?
actually, if you could enhance the sample plugin with code on how to do this for more than one additional option per category (stored in wp_options as an array) I would be over the moon.
Thanks For the tip Brad,
Just a quick note, I saw this implemented in WP e-Commerce for product Categories in 3.8, and noticed the alignment was off we fixed it by removing the and td’s and replacing it with
Could just be something we did, but thought I’ll leave a note..
best
jeff
thanks brad!
This tutorial has been very helpful for me… Thank you so much!
Brad, with your very helpful example, I was able to get started on a helper class to aid developers with adding meta data to taxonomies and other useful features. Early release on github … WPAlchemy_Taxonomy.
Hi, thanx for this tipp, you saved my life. I found out, that the code and the plugin you provide did not work with my theme on wordpress 3.0.4.:
Its because you use “edit_category_form_fields” instead of ” category_add_form_fields”
Great post! Really helps since the codex currently doesn’t have documentation on the form_fields hooks, or the edited_term hooks. Thanks again for the solution!
Is it possible to store letters as well as numbers using this? When I try to input anything but a number, it doesn’t store the data.