Question

I’m having an issue in my mongo group query: (this is PHP code)

$conditions = array(
                 'user' => array(
                      '$ne' => $uid
                 )
            );

            $group = $db->words->group(
                array("word" => true),
                array("count" => 0),
                "function(obj, prev) { prev.count += 1 }",
                $conditions
            );

Imagine the following documents in words collection

{
_id: 3,
word: "hello",
user: "test"
}
{
_id: 2,
word: "world",
user: ""
}
{
_id: 1,
word: "test",
user: ""
}

What I needed to be returned from the group command was:

{
    word: "world",
    count: 1
    }

I need to have only the words that have no user associated in any document. Currently I get:

{
    word: "test",
    count: 2
    }
{
    word: "world",
    count: 1
    }

Does this make sense? I’m still starting with mongo…

Thanks

Answer 1

I do not think you can filter the count directly within the group().

You will need to filter it out client side. I suspect this is prolly what you want anyway since you will wish to sort on count in one way or another (I know I would). So yea you will need to go through each doc taking out the count field.

I believe the aggregation framework will be nicer with this:

http://docs.mongodb.org/manual/reference/aggregation/#_S_group

You could use it as a pipe and then replace the field in another pipe after $sort or whatever.

Hope this helps,