Parse Server Aggregation using PHP SDK - php

Question

I'm trying to build an aggregation query in Parse's PHP SDK, and I'm stuck in the "lookup" area, I saw a JS example regarding this but it doesn't work in my case.
I have a table of users, which contains a "Tags" field of type Array, the array is actually an array of pointers, that point to a separate Tag class.
What I'm trying to achieve is to list most popular Tags based on their usage, so basically I need to query the users class and group the Tags that exist in the array, I already achieved this, but I'm stuck with the lookup part, the query currently returns an array of Tags pointers, what I want is to pull the object of those pointers.
Here's what I have currently:
$query = new ParseQuery('_User');
$pipeline = [
'project' => ['tags' => 1],
'unwind' => '$tags',
'group' => [
'objectId' => '$tags.objectId',
'count' => ['$sum' => 1]
],
'sort' => [ 'count' => -1],
'limit' => 10,
];
try {
return $query->aggregate($pipeline);
} catch (ParseException $ex) {
return $ex->getMessage();
}
And here's a snippet of what the _User collection looks like:
{
"_id" : "5BuBVo2GD0",
"email" : "test#test.com",
"username" : "test#test.com",
"lastname" : "Doe",
"firstname" : "John",
"_created_at" : ISODate("2017-01-23T09:20:11.483+0000"),
"_updated_at" : ISODate("2019-02-15T02:48:30.684+0000"),
"tags" : [
{
"__type" : "Pointer",
"className" : "Tag",
"objectId" : "St2gzaFnTr"
},
{
"__type" : "Pointer",
"className" : "Tag",
"objectId" : "LSVxAy2o74"
}
],
"_p_country" : "Country$4SE8J4HRBi",
}
And the Tag collection looks like this:
{
"_id" : "St2gzaFnTr",
"name" : "Music",
"_created_at" : ISODate("2018-10-22T20:00:10.481+0000"),
"_updated_at" : ISODate("2018-10-22T20:00:10.481+0000")
}
Any help would be appreciated!
Thanks in advance

Answer 1

Not sure if this is a direct answer, but here's a working aggregation on tags sorting for freq...
public function tagHistogram(Request $request, Response $response, array $args): Response {
$pipeline = [
'unwind' => '$tags' ,
'sortByCount' => '$tags',
'limit' => 1000,
];
$query = new ParseQuery('Product');
$result = $query->aggregate($pipeline);
$result = array_map(
function ($e) {
$e['name'] = $e['objectId'];
unset($e['objectId']);
return $e;
},
$result
);
return $response->withJson($result);
}