wordpress - display list of posts excluding a specific tag

Question

I want to display a list of posts that have a certain tag but don't have another specific tag. For examples, I have tried the following to display a list of posts which have 'animal' tag.

<?php 
    $args = array(
        'numberposts' => 1,
        'tag' => 'animal',
        'showposts' => 8
         );
    $query = new WP_Query($args);
    if($query->have_posts()):
        echo '<table>';
        while($query->have_posts()): $query->the_post();
             the_title(); ?> </a></td>

        endwhile;

    endif;
    wp_reset_query();                     

?>

How do we display a list of posts in 'animal' tag but not in 'cat' tag for example? I am very new with wordpress and just learned to create the custom page.

Answer 1

You are going to have to make use of a tax_query here to make this work. The normal tag parameters won't do the job.

Just a few notes on your original code

• showposts is depreciated in favor of posts_per_page

• numberposts is not valid in WP_Query

• Use wp_reset_postdata() for WP_Query, wp_reset_query() is used with query_posts which should never ever be used

• You need to call wp_reset_postdata() before endif just after endwhile

You will need something like this

$args = array(
    'posts_per_page' => '8',
    'tax_query' => array(
        'relation' => 'AND',
        array(
            'taxonomy' => 'post_tag',
            'field'    => 'slug', //Can use 'name' if you need to pass the name to 'terms
            'terms'    => 'animal', //Use the slug of the tag
        ),
        array(
            'taxonomy' => 'post_tag',
            'field'    => 'slug',
            'terms'    => 'cat',
            'operator' => 'NOT IN',
        ),
    ),
);
$query = new WP_Query( $args );