Change order of elements in query results array - php

Question

[edited] I need to display posts from database sorted in a kinda specific way.
There is a page which at set time interval query database via ajax to pull 180 latest post. Each post in db has column "source" which can be "instagram" or "twitter". Ajax returns 30 sets (or less) x 6 posts each (less if there is not enough posts). Than with help of js all sets are hidden and only one set (6 posts) is displayed at a time. After few seconds set is hidden and next one is shown. Think of it like a typical slideshow but with posts instead of images on infinite loop.
At the begining it wasn't important what kind of post were in sets. It could be all 6 posts from twitter or instagram or mixed. But as usual when project was scheduled to finish, I was asked to change the way sets are generated. Now client wants to have only 2 types of sets with posts in particular order (described below).
So my question is how change this (simplified example from my ajax file):
DB details for ref.: table POSTS: id / source / user / date etc.
$sql="SELECT * FROM posts ORDER BY id DESC LIMIT 180";
...
$stmt->setFetchMode(PDO::FETCH_OBJ);
$set=1;
while($row = $stmt->fetch()) {
if($set==1){
echo '<!--start set--><div class="set">';
}
if($row->source="twitter"){
echo '<div class="post twitter">';
echo '{all stuff related to this twitter post}';
echo '</div>';
} else if($row->source="instagram") {
echo '<div class="post instagram">';
echo '{all stuff related to this instagram post}';
echo '</div>';
}
if($set==6) {
echo '</div> <!--//END set-->';
$set=0;
}
}
$set++
}
into something what let me generate those 30 sets but with posts distributed among them using this pattern:
<!--First set should has post in order: --
<div class="set>
<div class="post twitter">{stuff}</div> {instagram post} {instagram post}
{instagram post}{instagram post}{twitter post}
</div> <!--//END set-->
<!--Second set order:-->
<div class="set">
{instagram} {instagram} {twitter}
{twitter} {instagram} {instagram}
</div>
etc.
Of course there is no guarantee that there would be enough post to create all 30 sets with those patterns so I need to create as many sets following those two patterns and leftovers put in sets as before simply in order they are pulled from db.
Thats all.
Thanks in advance for any suggestions / ready solutions ;) etc.

Answer 1

You could try something with a split between the two kind of posts using array_filter.
$posts = $stmt->fetchAll();
$twitterPosts = array_filter($posts, function($post){
return $post->source == "twitter";
});
$instagramPosts = array_filter($posts, function($post){
return $post->source == "instagram";
});
$set=1;
while(!empty($twitterPosts) && !empty($instagramPosts))
{
if($set%2 == 1)
{
$instagramPost1 = array_shift($instagramPosts);
$instagramPost2 = array_shift($instagramPosts);
$twitterPost1 = array_shift($twitterPosts);
}
else
{
$instagramPost1 = array_shift($instagramPosts);
$twitterPost1 = array_shift($twitterPosts);
$twitterPost2 = array_shift($twitterPosts);
}
/* display them */
if($set==6) {//your condition
echo '</div> <!--//END set-->';
$set=0;
}
$set++;
}
/* now one of them is empty, you can just display the other one */
if(!empty($twitterPosts))
/* Display all remaining twitter posts */
elseif(!empty($instagramPosts))
/* Display all remaining instagram posts */
Of course you should add validation that there is still something in the array between 2 array_shift.
I hope this helps !
EDIT : sorry I missed the condition for only 3 item per row, adding it now.