parsing mongoDB arrays

Take the following structure as an example:

db.greg1.save ( { 'name' : 'Rasheed Wallace', socialLinks : [ { 'id' : 'xyz', 'network' : 'Twitter' }
                                                             ,{ 'id' : 'qrs', 'network' : 'Facebook'}
                                                            ]
                }
)

Resolution:

• In mongoDB versions 2.2 and higher you can use the unwind command: http://docs.mongodb.org/manual/reference/aggregation/unwind/

  To unwind the array from the sample above, try the following as your MongoDBQuery in iReport Designer:

  { runCommand : { aggregate : 'greg1'
                              , pipeline : [ { $project : { name : 1, socialLinks : 1 }}
                                            ,{ $unwind  : '$socialLinks'}
                                           ]
                 }
  }
  

  This runcommand returns three fields: name, socialLinks.network, socialLinks.id .

• In mongoDB versions prior to 2.2 you can treat the array as a java.util.Collection object and pass it to a "net.sf.jasperreports.engine.data.JRMapCollectionDataSource" for use as a table or lists components dataset (other ideas like this here http://mdahlman.wordpress.com/2012/02/03/collections-in-reports-on-mongodb/)

• Finally a more difficult option is to create your own map-reduce functions. For shell syntax see: http://docs.mongodb.org/manual/core/map-reduce/. We have samples for calling the map-reduce function within iReport Designer here: Jaspersoft MongoDB Query Language (Map Reduce) & (Map Reduce Sample Query)

Ref. Case #00035314