Change link in get_terms if there is only one post in the category

Question

I created a shortcode that will list the categories in my custom taxonomy and will return a list of all the categories that have at least 1 post (not empty).

The result is that when someone clicks on my links it takes them to an archive page of that category.

My question is if it's possible that when there is only one post in that category, that i can send the user directly to the post instead of to the archive wiht only a single post on it?

this is my code:

// Creates a list of eval specialties
function doc_categories() {
$tax = 'team_group';  // slug of taxonomy to list

$terms = get_terms($tax, array('hide_empty' => 1 ));
$specials = '<div>';
foreach ($terms as $term) {
        $slug = $term->slug;
        $description = $term->description;
        $link = "<a href='/?$tax=$slug' ><h5> $term->name </h5></a>";
        $imglink ="<a href='/?$tax=$slug' ><img src='".z_taxonomy_image_url($term->term_id)."'></a>";

$specials .='<div class="flex_column av_one_third specialty flex_column_div">';
$specials .='<div class="specialty-name"'.$link.'</div>';
$specials .= $imglink;
$specials .= '</div>';
        }
$specials .= '</div>';
return $specials;
}
add_shortcode( 'evalspecialties', 'doc_categories' );

Answer 1

This could be done in the template that displays your archive page when only one post is returned by wp_query for a given category. Something like this:

if ( $wp_query->post_count == 1 && $wp_query->max_num_pages == 1 ) {
    wp_redirect( get_permalink( $wp_query->posts['0']->ID ) );
    exit;
}

Answer 2

FINAL EDIT

From comments

Unfortunately when I try method one, all links go back to the homepage

As I stated, everything works on my test install. I actually forgot that your code works for you, because you have hardcoded the URL

<a href='/?$tax=$slug' ><h5> $term->name </h5></a>

What this tells me is that get_term_link() is not returning the expected URL which 404's which gets redirected to the home page. This is caused, in all probability, because you did not flush your permalinks after you have created your taxonomy, or you have a permalink issue. You should sort that out first, and use my code in option 1 as benchmark. As I said, my code is now tested and everything is working as expected, so it should work for you as well

Just a tip, if something does not work, don't hide an issue the way you did, fix it. Simply hiding an issue can cause other unexpected stuff later on ;-)

ORIGINAL ANSWER

There are basically two ways to do this

• Inside your shortcode where you check the post count for the term and then query the single post and then showing that link instead of the category link

• Using the template_redirect hook to redirect the term page to the single post when $wp_query->found_posts returns 1

Just a note before I start. You should not create your own static links, they can cause issues when your permalink structure changes. Let get_term_link() handle the link building. In your context, you can simply pass the complete term object to get_term_link(). This does not cause extra db call, and you have a reliable link to the term page

NOTE: All code is untested

OPTION 1

You can try the following in your shortcode

add_shortcode( 'evalspecialties', 'doc_categories' );
function doc_categories()
{
    $tax      = 'team_group';  // slug of taxonomy to list
    $specials = ''; //Define $specials as a empy string

    // Get all the terms belonging to the team_group taxonomy
    $terms = get_terms( $tax );

    // IMPORTANT, make sure we have terms and also if we do not have a WP_Error
    if (    !$terms
         || is_wp_error( $terms )
    )
        return $specials;

    // Ok, everything checks out, lets continue
    $specials .= '<div>';
    foreach ( $terms as $term ) {
        // Just in case we somehow set hide_empty to false through a filter
        if ( 0 == $term->count )
            continue;

        $description = $term->description;
        $term_link   = get_term_link( $term );

        // If we have more than one post, show term link, otherwise show post permalink
        if ( 1 == $term->count ) {
            $args = [
                'posts_per_page' => 1,
                'fields'         => 'ids', //Just get postID
                'tax_query'      => [
                    [
                        'taxonomy' => $term->taxonomy,
                        'terms'    => $term->term_id,
                    ]
                ],
                // Add any extra parameter
            ];
            $q = get_posts( $args );
            $term_link = get_permalink( $q[0] );
        }

        $link        = '<a href="' . esc_url( $term_link ) . '"><h5>' . $term->name . '</h5></a>';
        $imglink     = '<a href="' . esc_url( $term_link ) . '"><img src="' . z_taxonomy_image_url($term->term_id) . '"></a>';

        $specials .= '<div class="flex_column av_one_third specialty flex_column_div">';
        $specials .= $link;
        $specials .= $imglink;
        $specials .= '</div>';
    } //endforeach

    $specials .= '</div>';
    return $specials;
}

OPTION 2

This is the better cleaner way to do it. Here you basically just chect the value of $found_posts, then redirect to the single post page if the value is 1. We will use template_redirect here.

First quickly modify your shortcode

add_shortcode( 'evalspecialties', 'doc_categories' );
function doc_categories()
{
    $tax      = 'team_group';  // slug of taxonomy to list
    $specials = ''; // Define $specials as a empy string

    // Get all the terms belonging to the team_group taxonomy
    $terms = get_terms( $tax );

    // IMPORTANT, make sure we have terms and also if we do not have a WP_Error
    if (    !$terms
         || is_wp_error( $terms )
    )
        return $specials;

    // Ok, everything checks out, lets continue
    $specials .= '<div>';
    foreach ( $terms as $term ) {
        // Just in case we somehow set hide_empty to false through a filter
        if ( 0 == $term->count )
            continue;

        $description = $term->description;
        $term_link   = get_term_link( $term );
        $link        = '<a href="' . esc_url( $term_link ) . '"><h5>' . $term->name . '</h5></a>';
        $imglink     = '<a href="' . esc_url( $term_link ) . '"><img src="' . z_taxonomy_image_url($term->term_id) . '"></a>';

        $specials .= '<div class="flex_column av_one_third specialty flex_column_div">';
        $specials .= $link;
        $specials .= $imglink;
        $specials .= '</div>';
    } //endforeach

    $specials .= '</div>';
    return $specials;
}

This will be the redirect action

add_action( 'template_redirect', function ()
{
    global $wp_query;

    // Check if found_posts is 1, if not, bail
    if ( 1 != $wp_query->found_posts )
        return;

    // Only target or taxonomy page
    if ( !is_tax( 'team_group' ) )
        return;

    // We only have one post, redirect to the single post page
    $single_post = $wp_query->post;
    $permalink   = get_permalink( $single_post );

    wp_redirect( esc_url( $permalink ) );
    exit;
});

EDIT

The code above is now tested and working