mongodb date aggregation operators timezone adjustments with php

aggregation-framework, date, mongodb, php, timezone

Solution

You can use `$project` with $subtract operator to make a -7 hour adjustment to a Date field:

{
    $project : { 
        ts : { $subtract : [ "$signs.timestamp", 25200000 ] }
    }
}

// 25200000 == 1000 milis x 60 sec x 60 mins x 7 h

The projected field `ts` is a Date that's offset by -7 hours.

Edit

This is the correct PHP syntax when using $subtract.

array(
    '$project' => array( 
        'ts' => array('$subtract' => array('$signs.timestamp', 25200000))
    )
)

Subtract accepts an array of values, not a key=>value pair.

Problem

I'm trying to adjust the timezone with date aggregation operators. I need to make -7 hours adjustment on the `$signs.timestamp` field. This is my code: ``` function statsSignatures() { $cursor = $this->db->collection->users->aggregate( array('$unwind' => '$signs'), array('$project'=>array( 'signs'=>'$signs', 'y'=>array('$year'=>'$signs.timestamp'), 'm'=>array('$month'=>'$signs.timestamp'), 'd'=>array('$dayOfMonth'=>'$signs.timestamp'), 'h'=>array('$hour'=>'$signs.timestamp') )), array('$group'=>array( '_id'=>array('year'=>'$y','month'=>'$m','day'=>'$d','hour'=>'$h'), 'total'=>array('$sum'=>1) )), array('$sort'=>array( '_id.year'=>1, '_id.month'=>1, '_id.day'=>1, '_id.hour'=>1 )) ); return $cursor['result']; } ``` I'm using MongoDB version 2.6.3. Thank you a lot !

Original source