Adding next & previous links for same node type, translation-aware

description

This snippet adds a custom next_prev_same_type function to your theme template.php.
This allows you to insert Next and Previous links in your *.tpl.php file.

This function selects previous/next items depending on the time the node was created with a single query.
Only published nodes of the same node type like the current node are selected.

If the next/previous node id retrieved from the database is one of the current nodes' translations,
next_prev_same_type runs again to skip that node. In this case, there will be a new sql query.

Step 1 of 2

Insert this code into your template.php

<?phpfunction next_prev_same_type($nid=null, $path=null, $direction=null)
{
  if($nid){
    // gather some node information
    $node = node_load($nid);
    $type = $node->type;
    $created = $node->created;
   
    // retrieve all node ids of this nodes' translations
    $translation_ids = array();
    foreach($node->translation as $translation) {
      if($translation->status == 1){
        $translation_ids[$key] = $translation->nid;
      }
    }
   
    // switch some vars depending on direction
    switch ($direction){
      case 'next':
        $modifier = ">";
        $order = "ASC";
        $link_str = "Next project ›";
        break;
      case 'prev':
      default:
        $modifier = "<";
        $order = "DESC";
        $link_str = "‹ Previous project";
    }
   
    // get next / prev element from database
    $query = db_query('select nid from {node} where type=\'%s\' AND status=1 AND nid!=%d AND created'.$modifier.'%d ORDER BY created %s, nid %s Limit 1',$type,$nid,$created,$order,$order);
    while ($item = db_fetch_object($query)){
      if($item->nid!=$nid && !in_array($item->nid,$translation_ids)){
        $nav_nid = $item->nid;
      }else{
        // skip element, if it is a translation of the current node
        return next_prev_same_type($item->nid,$path,$direction);
      }
    }
    if($nav_nid){
      return l(t($link_str),$path."/".$nav_nid);;
    }
  }
}?>

Step 2 of 2

Insert the code below somewhere in your *.tpl.php file (node.tpl.php, view_xyz.tpl.php, ...)

<?php
  $next = next_prev_same_type($node->nid, "your/path/here", "next");
  $prev = next_prev_same_type($node->nid, "yout/path/here", "prev");
  if($prev!= FALSE){
    $links[] = $prev;
  }
  if($next!= FALSE){
    $links[] = $next;
  }
  print theme_links($links, $delimiter = ' ')?>

OR

<?php
  print next_prev_same_type($node->nid, "your/path/here", "next");
  print next_prev_same_type($node->nid, "yout/path/here", "prev");?>

Format as desired.

function variables

next_prev_same_type($nid=null, $path=null, $direction=null)
$nid is the current node
$path is the path to be used in the link
$direction is either 'next' or 'prev'