In wordpress foreach loop, return current row id and next/prev row id

Question

In wordpress, I am trying to get current id of a row and a next id of upcoming row.

Example database:

    -----------------------------
    |   id  |   book  | orderby |
    -----------------------------
    |    3  |    b    |     1   |
    -----------------------------
    |    1  |    f    |     2   |
    -----------------------------
    |    2  |    g    |     3   |
    -----------------------------

code:

$entries = $wpdb->get_results( "SELECT * FROM ".$wpdb->prefix."_books" ORDER BY orderby ASC );
foreach ( $entries as $print ){
    $prev = //on second row this would be 3
    $current = $print->id  //on second row this would be 1
    $next =  //on second row this would be 2
}

I think in none Wordpress way you would just increase or decrease array key in loop. It is prolly simple fix.

Is there a reason why you are using `$wpdb->get_results` instead of the `WP_Query` or even `get_posts`? — Frits, Apr 13 '17 at 09:44
I have learned, that if you want to make query to custom database table you use get_results() for all rows and get_row() for single row and I have been using these methods. — user1203497, Apr 13 '17 at 09:50

score 2 · Accepted Answer · answered Apr 13 '17 at 09:49

You could use something like the following:

<?php

$entries = $wpdb->get_results("SELECT * FROM ".$wpdb->prefix."_books ORDER BY orderby ASC");
$entries = array_values($entries); //shouldn't be needed, but used just in case wordpress returns a non-incrementing key structure for whatever reason

foreach ($entries as $k=>$v) {
    if (isset($entries[$k - 1])) {
        $prev = $entries[$k - 1]->id;
    }
    else {
        $prev = null;
    }

    $current = $v->id;

    if (isset($entries[$k + 1])) {
        $next = $entries[$k + 1]->id;
    }
    else {
        $next = null;
    }
}

?>

+1 - this is almost exactly what I wanted to achieve, but you beat me to it. Type a little slower next time maybe ;) good job! — Frits, Apr 13 '17 at 10:02

In wordpress foreach loop, return current row id and next/prev row id

1 Answers1