wp_dropdown_categories() uses $term->id instead of $term->name for taxonomies that are not categories

[mfields]

I was excited to discover that wp_dropdown_categories() had been extended to support custom taxonomies but when I tried to implement it, the navigation failed because it always uses the $term->ID in the value attribute of the option tag for each term.

<option class="level-0" value="13">A Category</option>

This makes sense because WordPress category requests uses the term id: /?cat=13

But in the case of tags, we get this code:

<option class="level-0" value="3">My Tag</option>

which pulls a 404 when you request: /?tag=3

wp_dropdown_categories() only returns HTML. I imagine you're referring to the default widget in particular?

Replying to nacin:

wp_dropdown_categories() only returns HTML. I imagine you're referring to the default widget in particular?

I actually just finished up a plugin ​http://wordpress.mfields.org/2010/screenshot-of-the-new-taxonomy-widget-plugin/ that is a fork of the categories widget. It would have been simple to create except for the bug in wp_dropdown_categories(). To fix the bug, I had to rewrite functionality of wp_dropdown_categories(), walk_category_dropdown_tree() and the Walker_CategoryDropdown class.

The reported bug is in the html outputed by the Walker_CategoryDropdown class mainly this line:

$output .= "\t<option class=\"level-$depth\" value=\"".$category->term_id."\"";

Which works great for categories by does not work at all for other taxonomies.

/?cat=14

/?tag=my-tag-name

/?taxonomy=my-taxonomy-term-name

Categories are the only post taxonomy queried by id number, all others use slug. I reported this as a bug because I was looking through core and saw that wp_dropdown_categories() now allows the user to pass taxonomy as a key in the $args array.

This would be awesome to have fixed in core. Hopefully I have explained the issues well enough. You can see the changes that I needed to make to get my plugin functioning correctly here ​http://wordpress.pastebin.com/scckuBhp.

Thanks for your attention!

I want to move this to 3.1. I'm not really sure the best way to do restructure this. Ultimately, the categories widget still only takes categories. Ideally, we'd allow either a walker override, or the ability to use the slug instead of the ID.

The slug instead of the ID should probably be default for non-category taxonomies, which makes me want to revert taxonomy support for 3.0 from wp_dropdown_categories, or at least force a check in the walker to use the slug instead of the ID if it's a category. Then again, there are plenty of use cases (the JS functionality of the widgets not one of them) for the ID.

This bug also applies if a person wants to add a custom filter for taxonomies to edit.php . WP is expecting custom-taxes to have a slug as the query_var rather than the term_id and this means that the existing wp_dropdown_categories won't work for the custom filter. Like mfields, I have to create a custom dropdown function for the custom filter.

Viper007Bond is going to try to cook up a patch for this.

No patch. Punting.

Please patch this very old bug, 2 years old you postponed to 3.1, but it is not even in 3.4 - tons of people got problem with this (​http://wordpress.org/tags/wp_dropdown_categories)

and the solution is IMO very simple - just use

$output .= "\t<option class=\"level-$depth\" value=\"".$category->term_slug."\"";

instead of

$output .= "\t<option class=\"level-$depth\" value=\"".$category->term_id."\"";

on wp-includes/category-template.php row 953 for all other taxonomies then $category (or even for category and change the default select name to category instead of cat), or add another option to wp_dropdown_categories e.g. 'values' with default 'term_id' and then do something like

$output .= "\t<option class=\"level-$depth\" value=\"".$category->{$values}."\"";

Adds an optional 'value' argument to specify what should be used as for the value of the option (slug or ID). If unspecified reverts to ID for categories and slug otherwise.

In the meantime, its possible to replicate this by passing a custom walker which extends the Walker_CategoryDropdown class and replaces the start_el method. See this gist: ​https://gist.github.com/2902509

I just ran into this issue in a different context.

I use wp_dropdown_categories in a meta box to let the user pick a "primary" term from a custom taxonomy for a related custom post. Then, I filter get_posts in a shortcode to insert a list custom posts with that meta value. Only the dropdown still has the id values, so my shortcode query would by dependent on the order the custom terms were entered in the database.

I will have to use the custom walker (which is in use in the wild: ​http://stackoverflow.com/questions/14078572/how-to-change-value-for-options-and-select-in-wp-dropdown-categories), but why hasn't stephen1988's patch made it into core yet?