[PHP] About $size operator in aggregate $project

[張瀚文]

Hi:

I use php aggregate method to calculate group result, when I use $size operator in $project, 

like the following code 

array(

         '$project' => array(

                    "action_sum" => array('$size'=>'$action')

        )

),

the result as following

exception: invalid operator '$size'

I don't know what happened to my code, does any one know?

thanks a lot

PHP version is 5.5.9

reference: http://docs.mongodb.org/manual/reference/operator/aggregation/size/

[Rhys Campbell]

What version of MongoDB are you running? The docs state $size in new in v2.6

[張瀚文]

Thank you, your reply helps me a lot, the problem was found, our version of MongoDB is v2.4, I haven't noticed this situation.

Rhys Campbell於 2015年8月5日星期三 UTC+8下午4時46分31秒寫道：