Question

I’m trying to do a group query on a mongoDB but I get a wrong result and with all the tweaks it doesn’t solve my problem.

I have a collection with the following schema (action_ is a counter)

"_id": ObjectId(""),
"action_1": 3,
"action_2": 2,
"action_4": 0,
"shop": ObjectId(""),
"user": ObjectId(""),
"action_3": 33 

I need for each user to sum all counters from all shops, and I’ve did this:

$keys = array("action_1"=>1, "action_2"=>1, "action_3"=>1, "action_4"=>1); 
$initial = array("action_1"=>0, "action_2"=>0, "action_3"=>0, "action_4"=>0); 
$reduce = "function (obj, prev) { 
    prev.action_1 += obj.action_1; 
    prev.action_2 += obj.action_2; 
    prev.action_3 += obj.action_3; 
    prev.action_4 += obj.action_4; 
}";
$condition = array('user' => $user_id);
$g = $collection->group($keys, $initial, $reduce, $condition);

The result I get is an array of documents that extract the values. I need an array of associative arrays, and for every user to have something like:

array ("user") {
    action_1 => sum, //integer
    action_2 => sum,
    action_3 => sum,
    action_4 => sum
}

Answer 1

You will want to group by the user key instead then:

$keys = array("user"=>1);