So I understand you want to return only the helpers of some employee.
The find will always return a document from the collection, returning the document and the structure to support your projection. If you run this query:
db.teste.find(
{"funcionario.nome": "joão", "funcionario.ajudante.nome": 'manoel'},
{"funcionario.ajudante.nome": 1}
)
The return will include the array with all elements, but showing only the name of each helper. This is because in the query you are asking for a document that has an employee named "john", who has a helper named "manoel."
If you want to return only the helper in question, you need to use an aggregation:
db.teste.aggregate(
{$match: {"funcionario.nome" : "joão"}},
{$project: {"funcionario.nome" : 1, "funcionario.ajudante" : 1}},
{$unwind: "$funcionario"},
{$unwind: "$funcionario.ajudante"},
{$match: {"funcionario.ajudante.nome" : "manoel"}}
)
If you go get someone's helpers often who knows it's worth putting them in a separate collection, and save only the names or _id in an array inside the employee.
Most important : It does not make sense for you to save your company, your employees and helpers in a document only if you do not want to recover it at one time from the bank.
Gives you a look at modeling in Mongo, the most important thing is to think about how you will access / modify the data.
