Check for an already existing JOIN could be buggy

Hello,
I’m implementing an additional filter on the author page, that if is set, filter the posts on a custom taxomy. I’m doing this using a pre_get_posts and setting tax_query accordingly.

// A custom query var for the author page
function multi_tags( $query ) {
	$m_tag = $_GET['m_tag'];

    if ( $query->is_author() && !empty($m_tag) && $query->is_main_query()) {
		$taxquery = array(
	        array(
	            'taxonomy' => 'multi-tag',
	            'field' => 'id',
	            'terms' => array(259),
	        )
	    );
		    $query->set( 'tax_query', $taxquery );
    }
	}
add_action( 'pre_get_posts', 'multi_tags' );

Unfortunatly this wasn’t working, because I was getting the following SQL error:
Not unique table/alias: 'wp_term_relationships'
The point was that my tax_query was adding a JOIN that co authors already added. I found that in your code there’s already implemented a control against a JOIN (circa row 614 of co-authors-plus.php), but that control check for an INNER JOIN.
In order to solve my problem I had to check against LEFT JOIN, instead.

Probably that piece of code need to be revised. I’m avaialable if you need further details.

Thank you,

• This topic was modified 8 years, 3 months ago by llago.
• This topic was modified 8 years, 3 months ago by llago.