MongoDB aggregate query using PHP driver - php

Question

I have a working MongoDB aggregate query which I can run via the MongoDB shell. However, I am trying to convert it to work with the official PHP Mongo driver (http://php.net/manual/en/mongocollection.aggregate.php).
Here is the working raw MongoDB query:
db.executions.aggregate( [
{ $project : { day : { $dayOfYear : "$executed" } } },
{ $group : { _id : { day : "$day" }, n : { $sum : 1 } } } ,
{ $sort : { _id : -1 } } ,
{ $limit : 14 }
] )
Here is my attempt (not working) in PHP using the Mongo driver:
$result = $c->aggregate(array(
'$project' => array(
'day' => array('$dayOfYear' => '$executed')
),
'$group' => array(
'_id' => array('day' => '$day'),
'n' => array('$sum' => 1)
),
'$sort' => array(
'_id' => 1
),
'$limit' => 14
));
The error from the above PHP code is:
{"errmsg":"exception: wrong type for field (pipeline) 3 != 4","code":13111,"ok":0}
Any ideas? Thanks.

Answer 1

The parameter in your Javascript is an array of 4 objects with one element each, in your PHP it's an associative array (object) with 4 elements. This would represent your Javascript:
$result = $c->aggregate(array(
array(
'$project' => array(
'day' => array('$dayOfYear' => '$executed')
),
),
array(
'$group' => array(
'_id' => array('day' => '$day'),
'n' => array('$sum' => 1)
),
),
array(
'$sort' => array(
'_id' => 1
),
),
array(
'$limit' => 14
)
));
In addition, if you have at least PHP5.4, you can use simpler array syntax. Transformation to PHP is then trivial, you simply replace curly braces with square brackets and colons with arrows:
$result = $c->aggregate([
[ '$project' => [ 'day' => ['$dayOfYear' => '$executed'] ] ],
[ '$group' => ['_id' => ['day' => '$day'], 'n' => ['$sum' => 1] ] ],
[ '$sort' => ['_id' => 1] ],
[ '$limit' => 14 ]
]);

Answer 2

You can also use the JSON array directly:
$json = [
'{ $project : { day : { $dayOfYear : "$executed" } } },
{ $group : { _id : { day : "$day" }, n : { $sum : 1 } } } ,
{ $sort : { _id : -1 } } ,
{ $limit : 14 }'
];
$pipeline = [];
foreach ($json as $stage) {
array_push($pipeline, toPHP(fromJSON($stage)));
}
$result = $c->aggregate($pipeline);
You can also use combination like this:
use function MongoDB\BSON\toRelaxedExtendedJSON;
use function MongoDB\BSON\fromPHP;
use function MongoDB\BSON\toPHP;
use function MongoDB\BSON\fromJSON;
$operator = '$dayOfYear';
$json = [];
array_push($json, toRelaxedExtendedJSON(fromPHP(
array('$project ' => array('day' => array($operator => '$executed')))
)));
array_push($json,
'{ $group : { _id : { day : "$day" }, n : { $sum : 1 } } } ,
{ $sort : { _id : -1 } } ,
{ $limit : 14 }'
);
$pipeline = [];
foreach ($json as $stage) {
array_push($pipeline, toPHP(fromJSON($stage)));
}
$result = $c->aggregate($pipeline);
or
$operator = '$dayOfYear';
$json = [];
array_push($json,
'{ $group : { _id : { day : "$day" }, n : { $sum : 1 } } } ,
{ $sort : { _id : -1 } } ,
{ $limit : 14 }'
);
$pipeline = [];
array_push($pipeline, array('$project ' => array('day' => array($operator => '$executed'))));
foreach ($json as $stage) {
array_push($pipeline, toPHP(fromJSON($stage)));
}
$result = $c->aggregate($pipeline);
If your aggregation query is dynamic or based on user-input be aware of NoSQL-Injection!
https://www.acunetix.com/blog/web-security-zone/nosql-injections/