Syntax help needed: Taxonomy Query

Question

I have a template called taxonomy-book_style.php to handle all the terms in book_style. On it I just have a simple loop

<?php if (have_posts()) : while (have_posts()) : the_post();?>

I would like to order my posts by the meta key value found in the meta_key tf_book_sort

So far I've tried these but they do not work:

<?php 
query_posts( $query_string . 'orderby=meta_value&meta_key=tf_book_sort&order=ASC' );?>
<?php if (have_posts()) : while (have_posts()) : the_post();?>

<?php if (have_posts()) : while (have_posts()) : the_post('meta_key=tf_book_sort&orderby=meta_value&order=ASC'); ?>

<?php 
$args = array(
'tax_query' => array(array('taxonomy' => 'book_style')),
'meta_key' => 'tf_book_sort',
'orderby' => 'meta_value',
'order' => 'DESC'
);?>
<?php query_posts ($args);?>
<?php if (have_posts()) : while (have_posts()) : the_post(); ?>

The nested arrays are confusing, can someone please suggest a proper synatx to accomplish sorting these posts by a meta key value?

Thank You.

Answer 1

first of all, let's just forget query_posts exists. there's no good reason to use it, ever.

the best way to do this is via the pre_get_posts action in your theme's functions.php. you don't have to set any taxonomy parameters, those are already set on a taxonomy archive page, you just need meta key and orderby:

function wpa65258_tax_meta_orderby( $query ) {
    if ( is_tax( 'book_style' ) && is_main_query() ) : // edit -> added is_main_query()
        $query->set( 'meta_key', 'tf_book_sort' );
        $query->set( 'orderby', 'meta_value_num' );
    endif;
}
add_action( 'pre_get_posts', 'wpa65258_tax_meta_orderby' );

This assumes your meta value is numeric. if it's not, change orderby to meta_value instead of meta_value_num.

Then in your template, just do the normal loop:

if (have_posts()) : while (have_posts()) : the_post();

etc..