Mongodb group joining two collection

[marcolinux]

 I was wondering if it possible to using group (specifically, in the keyf function) to join 2 collections.

MYCOLL.collection.group(:keyf => "function(doc) { var var2Item=db.mycoll2.find({\"_id\":doc.my_sub_id}); var2=var2Item.join_var; return {'myreturn': doc.var1 + var2 }; }",     
:initial => { :r => 0 }, 
:reduce => "function(doc,prev) { prev.r += +1; }", 
:cond => {( ...my_conditions...)})

I have also tried

var2=doc.my_sub_id.join_var    

and neither seems to work. I am using the Ruby Driver, but it is not really important, as the query is (practically) raw.

[Sam Millman]

I don't think the db object is available witin the group, does it just output an error or nothing at all?

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[marcolinux]

There is no error, but in all case it is outputting "undefined" (so it is not recognizing the query).

On Monday, April 23, 2012 9:54:00 PM UTC+9, Sammaye wrote:

I don't think the db object is available witin the group, does it just output an error or nothing at all?

[Sam Millman]

Yea you can't do that, it was a long shot to see but hey.

In order to join you'll have to find some other way join them.

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