query_posts with custom taxonomy - php

Question

This is to create a custom RSS feed. I have a CPT called quotes with a Taxonomy called quote_category
I want all posts where quote_category = 'Dogs' which has ID = 115. This isn't working:
$postCount = 10; // The number of posts to show in the feed
$postType = 'quotes'; // post type to display in the feed
$catName = 'Dogs';
$posts = query_posts(array('post_type'=>$postType, 'quote_category'=>$catName, 'showposts' => $postCount));

Answer 1

Generally speaking the consensus is to avoid query_posts at all costs. The official documentation even backs this up:
Note: This function will completely override the main query and isn’t intended for use by plugins or themes. Its overly-simplistic approach to modifying the main query can be problematic and should be avoided wherever possible. In most cases, there are better, more performant options for modifying the main query such as via the ‘pre_get_posts’ action within WP_Query.
Instead, get_posts() will do everything that you want it to do. For your case, you just want to add on a tax_query with your information.
$posts = get_posts(
[
'post_type' => 'quotes',
'numberposts' => 10,
'tax_query' => [
[
'taxonomy' => 'quote_category',
'field' => 'name',
'terms' => 'Dogs',
],
],
]
)
The terms parameter also accepts an array if you need multiple:
'terms' => ['Dogs', 'Cats'],
Edit
If you are using get_template_part then you are probably also using the standard WordPress loop, too. That is actually one of the few times that you could use query_posts but I still personally just don't use it nor recommend it. In an ideal world, you'd probably use a filter just as pre_get_posts but I unfortunately I don't have time to write code to test that. You should be able to use the below code.
This code is an action that calls an anonymous function which adds a feed using another anonymous function as a callback. Your code does the exact same thing, however you are using named functions which is 100% fine, safe and common to do. I just personally prefer to keep my hooks and logic all together and not chase names down. Once again, totally personal preference.
If you still receive an internal error, make sure that both WordPress and PHP debugging is enabled so that you can see what the actual error is, and it is probably a little typo on my part.
add_action(
'init',
static function () {
add_feed(
'quotes',
static function () {
// Override the main query since the render functions wants to use the loop
global $wp_query;
$wp_query = new WP_Query(
[
'post_type' => 'quotes',
'post_count' => 10,
'tax_query' => [
[
'taxonomy' => 'quote_category',
'field' => 'name',
'terms' => 'Dogs',
],
],
]
);
get_template_part('rss', 'quotes');
}
);
}
);