Unable to get all tags from specific categories

Question

Page in question.

I'm trying to use a WP_Query(); targeting specific categories and displaying all the tags used for posts within those categories.

I noticed that some tags, like truffles aren't being included in the results even though that post is categorized as a recipe and it's other category, sweets, is also included in the category array.

Any thoughts on what I'm doing wrong so as to get only some of the tags? Thanks!

    <ul class="tag-list">
    <?php

      $query = new WP_Query( 'cat=4,101,94,93,56,72,99,100,63,98,95,96,80' );

        $posttags = "";
        if (have_posts()) : while (have_posts()) : the_post();

            if( get_the_tag_list() ){
                $posttags = $posttags . get_the_tag_list('',',',',');
            }

        endwhile; endif; 

      wp_reset_postdata();  

        // Explode tags in array
        $sortedtags = explode(',', $posttags);

        // Sort array
        asort($sortedtags);            

        // Remove duplicates from array
        $sortedtags = array_unique($sortedtags);

        // Remove the blank entry due to get_the_tag_list
        $sortedtags = array_values( array_filter($sortedtags) );

        foreach ($sortedtags as $tagname) {
        echo '<li>' . $tagname . '</li>';
        }

    ?>
    </ul>

Update

I thought my used of the main loop if (have_posts)...the_post(); was screwing things up so I edited the code, but I'm still missing my my mushrooms! :P

    <ul class="tag-list">
    <?php

  $query_args = array( 'cat' => '4,101,94,93,56,72,99,100,63,98,95,96,80' );
  $query = new WP_Query( $query_args );

    $posttags = "";
    while( $query->have_posts() ) {
        $query->the_post();
    if( get_the_tag_list() ){
        $posttags = $posttags . get_the_tag_list('',',',',');
    }
    }

  wp_reset_postdata();  

    // Explode tags in array
    $sortedtags = explode(',', $posttags);

    // Sort array
    asort($sortedtags);            

    // Remove duplicates from array
    $sortedtags = array_unique($sortedtags);

    // Remove the blank entry due to get_the_tag_list
    $sortedtags = array_values( array_filter($sortedtags) );

    foreach ($sortedtags as $tagname) {
    echo '<li>' . $tagname . '</li>';
    }

    ?>
    </ul>

Answer 1

Looks like all I needed was to include 'posts_per_page' => -1 in the $query_args array.

Final, working code:

    <ul class="tag-list">
        <?php

        $query_args = array(
            // Easier to call the parent category, "recipe" instead of dealing with all these ids
            // 'cat' => '101,94,93,56,72,99,100,63,98,95,96,80,4',
            // Calling recipes (4) and ingredients (56) category ids - specific recipe types that are children of recipes get included
            'category__in' => array( 4, 56 ),
            // Grabs all posts, not just the ones on the first page
            'posts_per_page' => -1
        );
        $query = new WP_Query( $query_args );
        //  $query = new WP_Query( 'author_name=centehua' );

        $posttags = "";
        while( $query->have_posts() ) {
            $query->the_post();
          if( get_the_tag_list() ){
              $posttags = $posttags . get_the_tag_list('',',',',');
          }
        }

        wp_reset_postdata();  

        // Explode tags in array
        $sortedtags = explode(',', $posttags);

        // Sort array
        asort($sortedtags);            

        // Remove duplicates from array
        $sortedtags = array_unique($sortedtags);

        // Remove the blank entry due to get_the_tag_list
        $sortedtags = array_values( array_filter($sortedtags) );

        foreach ($sortedtags as $tagname) {
          echo '<li>' . $tagname . '</li>';
        }

        ?>
    </ul>

Answer 2

you're trying to concatenate the tag lists for all posts into a single string, which may not be the best approach and issue with how you are retrieving and concatenating the tags within your loop.

<ul class="tag-list">
    <?php
    $query = new WP_Query('cat=4,101,94,93,56,72,99,100,63,98,95,96,80');

    $all_tags = array();

    if ($query->have_posts()) : while ($query->have_posts()) : $query->the_post();
            $post_tags = get_the_tags();

            if ($post_tags) {
                foreach ($post_tags as $tag) {
                    $all_tags[] = $tag->name;
                }
            }

    endwhile;
    endif;

    wp_reset_postdata();

    // Sort and remove duplicates
    $sorted_tags = array_unique($all_tags);
    asort($sorted_tags);

    foreach ($sorted_tags as $tag_name) {
        echo '<li>' . $tag_name . '</li>';
    }
    ?>
</ul>