Mongodb: sort documents by array objects

Question

I would like to return the documents in an order sorted by which holds the lowest foo.bar value (which are array objects).

I can do db.collection

Answer 1

You can do such a sort with aggregate command from mongo version 2.2:

    db.collection.aggregate([{$unwind: "$foo"},
    {$project: {bars:"$foo.bar"}},
    {$group: {_id:"$_id",min:{$min: "$bars"}}},
    {$sort: {min:1}}])