Foreach in foreach [PHP] - php

Question

Actually I work with PHP framework Codeigniter and I want to compare value from first foreach to second one, but I'm getting an error. Example here:
<?php foreach($posts->result() as $post): ?>
(html content)
<?php foreach($tags->result() as $tag) {
if($tag->id_users == $post->id_users) echo $tag->tag_name;
} ?>
(html content)
<?php endforeach; ?>
When I compare $post->id_users inner second foreach I'm getting error, how can I get around this?

Answer 1

Its better to avoid loop inside a loop
$tag_ids = array();
foreach($tags->result() as $tag) {
$tag_ids[] = $tag->id_users;
}
foreach ($posts->result() as $key => $post) {
if(in_array($post->id_users, $tag_ids)) {
}
}

Answer 2

You don't close the second foreach. For eg
<?php foreach($posts->result() as $post): ?> foreach1
(...some html)
<?php foreach($tags->result() as $tag) { if($tag->id_users == $post->id_users) echo $tag->tag_name; } ?> //foreach2
(...some html)
<?php endforeach; ?>
<?php endforeach; ?>

Answer 3

You should not use $posts->result() and $tags->result() inside foreach loop. Because it will go to check for every time while foreach is live.
Overall it decrease the performance of script.
<?php
$posts = $posts->result();
$tags = $tags->result();
foreach($posts as $post) {
?>
<< Other HTML code goes here >>
<?php
foreach($tags as $tag) {
if($tag->id_users == $post->id_users) {
echo $tag->tag_name;
}
?>
<< Other HTML code >>
<?php
}
}