Ivan.Srb questions

Ivan.Srb answers

• "errmsg" : "exception: $unwind: value at end of field path must be an array"
• Mongodb aggregate match array item with child array item
• Reverse array field in MongoDB
• Unwind empty array in mongodb
• MongoDB aggregate return count of 0 if no results
• MongoDB setOnInsert and push if already existent
• Mongodump with Replica Set : how to force on secondary?
• MongoDB, update collection field if new value is not null