Unable to aggregate subdocuments

[andrewryno]

I'm having a problem where I can't aggregate subdocuments. The problem is that my $columns argument has columns like subdocument.key. Mongo doesn't like that and spits out this error:

exception: the group aggregate field name 'metrics.clicks' cannot be used because $group's field names cannot contain '.'

Dump of the $group pipeline looks like this:

array(2) [
    '_id' => integer 0
    'metrics.clicks' => array(1) [
        '$sum' => string (15) "$metrics.clicks"
    ]
]

I'm not sure if this is even possible to fix without deviating too much from the Laravel query builder. Could possibly add a third optional parameter to rename columns, but I don't know if that would be wise.

Possibly introduce some set of characters to denote spaces, pass that to Mongo, and then split by those characters when Mongo comes back with the aggregates?

[rms2219]

Can you use a "project" before the group to project $metric.clicks to something without a '.' in it? In my case, I have a "Order" document with an array of "Line" documents...I called $unwind on $lines and then projected "order.lines.cost" to 'cost', which I could then group:

MyModel::raw(function($collection){
               return $collection->aggregate(array(
                   array('$unwind' => '$lines'),
                   array('$project' => array(
                       'orderName' => '$orderName',
                       'cost' => array('$add' => '$lines.cost')
                   )),
                   array('$group' => array(
                       "_id" => '$orderName',
                       "lineCost" => array('$sum' => '$cost')
                   )),
               ));
            });

[andrewryno]

I'm really trying to avoid having to use a raw query, simply because I just moved away from the default PHP driver for that reason. :P

So I was able to get this working. When you use the aggregate functions, it's completely unnecessary for the highest level key (in this case metrics.clicks) to be descriptive. So I did a "hacky" str_replace to fix it.

I can provide a patch/tests if anyone wants. It doesn't change the output at all. I get my aggregations perfectly. :)

[rms2219]

I'd like to see how you did the aggregations without a raw query...I couldn't figure out what the format was for subdocuments, so I switched to raw.

[jenssegers]

What would be the best solution; replace metrics.clicks with 'metrics_clicks', or just 'clicks'?

[andrewryno]

Probably underscore, although it really doesn't matter since that key isn't used anywhere else, since the aggregate() function itself uses return $results[0][$columns[0]]; instead of a key string.

I'm working on a pull request right now.

[jenssegers]

Sweet!

[andrewryno]

Done in #29.