List category posts alphabetically on archive.php

Question

I have a bunch of categories with sub-categories and sub-sub-categories that I want to list on my archive.php. The titles of the sub-categories are listed on the archive page of its parent category.

Just list the linked titles of the categories and/or posts, nothing more. Everything works perfectly, but on the last step I'd like to order the actual posts alphabetically.

So I have this code in my archive.php

<?php
if (is_category()) {
    $this_category = get_category($cat);
}

$this_category = wp_list_categories('orderby=name&depth=1&show_count=0&title_li=&use_desc_for_title=1&child_of='.$this_category->cat_ID."&echo=0");

if ($this_category && $catlvl !=0) { ?> 
    <ul class="cat_options">
<?php 
if ($catlvl !=3){
    if ($catlvl == 1){
        // Do stuff
    }
    if ($catlvl == 2){
        // Do stuff
    }
} else {
    // Do stuff
    $wpex_count = 0;
    while ( have_posts() ) : the_post();
        $wpex_count++;

        // Get entry title ?>
        <li>
        <a href="<?php wpex_permalink(); ?>" title="<?php wpex_esc_title(); ?>" rel="bookmark"><?php the_title(); ?></a>
        </li> <?php                            

        // Reset counter to clear floats
        if ( wpex_blog_entry_columns() == $wpex_count ) {
            $wpex_count=0;
        }

    endwhile;
}
?>
</ul>
<?php }

How do I make it so it lists the posts alphabetically on the last step? On the pages where it lists categories they are in alphabetical order.

Can I use

$args = array( 'posts_per_page' => -1, 'orderby'=> 'title', 'order' => 'ASC' );

from https://codex.wordpress.org/Alphabetizing_Posts here somehow? How? Or do I need to get my posts in some other way?

Only posts in the current category should be listed. When I use the method in the link above it lists ALL posts in ALL categories.

Answer 1

I suggest you use the pre_get_posts action hook provided by WordPress.

Then, in your functions.php add the following code below:

function custom_pre_get_posts($query) {
    // validate
    if(!is_admin() && $query->is_main_query()) {

        if(is_archive()) {
            $query->set('orderby', 'title'); // order posts by title
            $query->set('order', 'ASC'); // and in ascending order
        }
    }
}
add_action('pre_get_posts', 'custom_pre_get_posts');

You can learn more about pre_get_posts in here