Insert object in nested array mongodb nodejs - arrays

Question

So I am trying to insert an object in parameters and have been unsuccessful. My mongodb structure looks like this:
[
{
"_id": "04",
"name": "test service 4",
"id": "04",
"version": "0.0.1",
"title": "testing",
"description": "test",
"protocol": "test",
"operations": [
{
"_id": "99",
"oName": "test op 52222222222",
"sid": "04",
"name": "test op 52222222222",
"oid": "99",
"parameters": {},
"description": "testing",
"returntype": "test"
},
{
"_id": "58",
"oName": "test op 52222222222",
"sid": "04",
"name": "test op 52222222222",
"oid": "58",
"parameters": {},
"description": "testing",
"returntype": "test"
}
]
}
]
I want to be able to add an object into parameters with basic details such as name, id, and type. I am not entirely sure how to tackle this as I have all other CRUD operations implemented up until the parameters part. How should I go about to complete this? I know mongodb has issues when trying to insert something into an array inside an array, so if anyone has any suggestions as to how I can complete this I would really appreciate it. Thanks.
One of the problems is I do not have access to the _id of the root object, but I do have the _id for the operation where I am inserting the parameter. Hence I was trying to insert the parameter using this code:
collection.update({"operations":{"$elemMatch": {"oid": oid}}}, {'$addToSet':{"operations.parameters": {name: "test"} }}, {safe:true}, function(err, result) {
if (err) {
res.send({'error':'An error has occurred'});
} else {
res.send(result[0]);
}
});
This does not work though.

Answer 1

I was able to complete the insert by using the following code:
collection.update({ "operations": {$elemMatch: {_id:oid}}}, {$addToSet: { "operations.$.parameters" : parameter}}, function(err, result) {
if (err) {
res.send({'error':'An error has occurred'});
} else {
res.send(result[0]);
}
});
Just in case anyone needed it.

Answer 2

This is because you need to use positional operator, The example I am copying from the link is almost the same as in your case:
db.students.update(
{ _id: 4, "grades.grade": 85 },
{ $set: { "grades.$.std" : 6 } }
)