How to add data in nested array in mongoshell - node.js

Question

I have a schema :
{
"id": String,
"username": String,
"password": String,
"email": String,
"firstName": String,
"lastName": String,
"system" : {
"item" : {type: Number},
"update_interval" : { type: Number, max: 99999 },
"reading" : [
{
"id" : { type: Number},
"adc1" : { type: Number, max: 4095 },
"adc2" : { type: Number, max: 4095 },
"pc_datestamp" :Date,
}
]
}
now i want to add values to
"reading" : [
{
"id" : { type: Number},
"adc1" : { type: Number, max: 4095 },
"adc2" : { type: Number, max: 4095 },
"pc_datestamp" :Date,
}
]
but i dont know where I am wrong I have tried to update data from mongoshell but no success till now
> db.users.update( {"email" : "test#test.com", "system.item": 1, }, {"$push": {"system.$.reading": [{"adc1" : "123", "adc2": "1245", "id":"1" }] } })
WriteResult({
"nMatched" : 0,
"nUpserted" : 0,
"nModified" : 0,
"writeError" : {
"code" : 16837,
"errmsg" : "The positional operator did not find the match needed from the query. Unexpanded update: system.$.reading"
}
> db.users.update( {"email" : "test#test.com", "system": {$elemMatch:{ item: 1}} }, {"$push": {"system.$.reading": {"adc1" : "123", "adc2": "1245", "id":"1" } } })
WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0 })
I have set the value of item as one
> db.users.find( {"email" : "test#test.com", "system.item": 1} ).pretty()
{
"_id" : ObjectId("56dd88578ff7fbd714091a4a"),
"lastName" : "test",
"firstName" : "test",
"email" : "test#test.com",
"password" : "$2a$10$wY9wr9oreza4fBX7CfXym.rPZUPrcesigYIfWd0zbM4dDjBy6k3vy",
"username" : "test",
"system" : {
"item" : 1,
"reading" : [ ]
},
"__v" : 0
}
I have followed
Mongodb $push in nested array
and this
Insert data in nested array in mongodb
and many more questions but cannot find whats wrong.

Answer 1

Since the positional $ operator acts as a placeholder for the first element that matches the query document, and the array field must appear as part of the query document, your update
operation does not satisfy these conditions hence it suffers from the error fate you are getting. In your query you are only referencing the "system.item" field which is not an array.
The other option you can do is ditch the positional $ operator in your update and just add the object to the array using $addToset which adds elements to an array only if they do not already exist in the set:
db.users.update(
{
"email": "test#test.com",
"system.item": 1
},
{
"$addToSet": {
"system.reading": {
"adc1" : "123",
"adc2": "1245",
"id":"1"
}
}
}
)