Take the 2-minute tour ×
WordPress Development Stack Exchange is a question and answer site for WordPress developers and administrators. It's 100% free, no registration required.

I've build a custom post type for a calendar and created a structure like this:

  • 2012 (general parent)
    • January-2012
      • 1-January-2012 -2-January-2012
      • ...
      • ...
    • Februar-2012
      • 1-February-2012
      • 2-February-2012
      • ...
      • ...
    • March-2012
      • 1-March-2012
      • 2-March-2012
      • ...
      • ...

If I am now on the side for the whole month, I want to display a link to the pages for the previous and next month.

example: January <-- February --> March

I tried *get_previous_posts_link()* and get NULL, then I set global $post and get NULL too.

Another question, is this in general the right way? Maybe then I get the post data / link for 31st January? I'm not sure if *get_previous_posts_link()* considers the hierarchy.

share|improve this question
    
How is this "hierarchy" built? Is this a menu? A post type? How are the dates set? –  s_ha_dum Jul 3 '13 at 14:35
    
It's a custom post type. The dates are the titles of the posts. To achieve this hierarchy, I used a parent-child-relationship like standard-pages: a year-post is the parent, it has the month as children, each month has children again, the days of a month. –  skamander Jul 7 '13 at 15:04
add comment

2 Answers

up vote 1 down vote accepted

Well... I don't think get_previous_posts_link would help you. It only return link to the previous set of posts within the current query. (see previous_posts_link it prints this link, and get_previous_posts_link returns it).

And quote from Codex:

Prints a link to the previous set of posts within the current query.

If you need the values for use in PHP, use get_previous_posts_link().

Because post queries are usually sorted in reverse chronological order, next_posts_link() usually points to older entries (toward the end of the set) and previous_posts_link() usually points to newer entries (toward the beginning of the set).

You could try with these plugins:

But I'm not sure if they will work correctly.

I always do it with my custom SQL query - it's more efficient, because you don't have to select all pages (and all info about these pages).

function my_get_next_page_link($post_id =null) {
    global $post, $wpdb;
    if ( $post_id === null )
        $p = $post;
    else
        $p = get_post($post_id);

    $res_id = $wpdb->get_var(
        $wpdb->prepare("SELECT ID FROM {$wpdb->posts} WHERE post_type='page' AND post_status='publish' AND post_parent = %d AND menu_order > %d ORDER BY menu_order ASC, ID ASC LIMIT 1", $p->post_parent, $p->menu_order)
    );

    if ( !$res_id )
        return null;
    return get_permalink($res_id);
}

Of course you should write your own SQL query inside this function (it depends on your query params). You can write same function for previous page link.

PS. Probably it's not the easiest way of doing it, but it is efficient and very customizable (if you know SQL).

share|improve this answer
    
menu_order is not set ( set to 0 ) for most posts and post types so I'd worry that this won't sort by date the way the OP need. –  s_ha_dum Jul 3 '13 at 14:10
    
@s_ha_dum: WordPress sorts posts by menu_order and then by ID (when you use menu_order) and I think he is - he somehow build this hierarchy (page_parent and menu_order is what I would bet on). –  Krzysiek Dróżdż Jul 3 '13 at 18:12
    
Yes, this definitely might work depending on how this is constructed. (I am waiting on clarification on that point from the OP.) It is just not guaranteed to work except under limited circumstances. –  s_ha_dum Jul 3 '13 at 18:21
    
Yes, you're right - this solution is based on assumption, that this structure is defined using parents and menu_order. –  Krzysiek Dróżdż Jul 3 '13 at 18:28
add comment

I agree with @Krzysiek, if you are up to it, you can and probably should do it yourself.

Otherwise you can go with the following two plugins:

They are very much customizable in terms of link options. I have very good experience using them up to WP 3.5.

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.