How do I translate a MongoDB aggregation pipeline to PHP? - php

Question

I am using the following MongoDB query (and it's working with RoboMongo), returning an array with 30 elements, one for each day of the date range specified on $match element:
db.alcobaca.aggregate( [
{ $project:
{ time:1,
temp:1,
frio:
{
$cond:
[{ $lte: [ "$temp", 7.2 ] }, 0.25, 0 ]}}},
{
$match: {
time: {
$gte: new Date('11/01/2011'),
$lt: new Date('11/30/2011')
}
}
},
{
$group: {
_id: {
ord_date: {
day: {$dayOfMonth: "$time"},
month: {$month: "$time"},
year: {$year: "$time"}
}
},
horasFrio: { $sum: '$frio' }
}
},
{ $sort: { '_id.ord_date': 1} }
])
When I translate to PHP, working on the Laravel framework, after a successful connection to the database (I have already tested it with another, simpler query):
$c->aggregate (
[
['$project' =>
['time' => 1,
'temp' => 1,
'frio' =>
['$cond' =>
[['$lte' => ['$temp', 7.2]], 0.25, 0]]]],
['$match' => [
'time' => [
'$gte' => new DateTime('11/01/2011'),
'$lt' => new DateTime('11/03/2011')
]
]
],
[
'$group' => [
'_id' => [
'ord_date' => [
'day' => ['$dayOfMonth' => '$time'],
'month' => ['$month' => '$time'],
'year' => ['$year' => '$time']
]
],
'horasFrio' => ['$sum' => '$frio']
]
],
['$sort' => ['_id.ord_date' => 1]]
]
);
It returns an empty array. Am I missing some syntax issue?
Thank you