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  1. Core Server
  2. SERVER-14876

support $elemMatch in aggregation $project operator

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Details

    • Improvement
    • Status: Closed
    • Major - P3
    • Resolution: Duplicate
    • 2.6.4
    • None
    • Aggregation Framework
    • None

    Description

      Why can't $elemMatch be used in the $project phase? It would allow me to easily select an element out of an array.

      Example:

      db.person.aggregate([
        { "$project": {'main_event' :
          {'$events_array': {'$elemMatch' : {
            'event_status' : 'main'
          }}}
        }}
      ]);

      Basically what I'm looking for is an easier way to convert an array into a scalar without having to $unwind and then re-$group, which is taxing for proc time.

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              Unassigned Unassigned
              nefiga Ben Rotz
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                Updated:
                Resolved: