Retrieving Mongo Array Value into Flat Files

Assume that you have a collection with below document structure and you need to export the values in readable csv format. We can achieve this easily by using MONGOEXPORT function as stated below: 

>mongoexport --type=csv -d school -c students -f _id, name, scores.0.type, scores.0.score -o export.csv

The above command will create a export.csv file with following format:

_id	scores.0.type	scores.0.score	name
19	exam	44.51211102	Gisela Levin
20	exam	42.174398	Tressa Schwing
21	exam	46.22894763	Rosana Vales
22	exam	75.04996548	Margart Vitello

In case you want to apply any query filter, then you can use -q option in the command:
>mongoexport --type=csv -d school -c students -f _id, name, scores.0.type, scores.0.score  -q {_id:{$gte:19}} -o export.csv

Here I retrieve student data with _id >= 19.