How to rename keys of items in an array - node.js

Question

I am very new to MongoDB and I need to do a somewhat complex Update operation on my collection.
I have this kind of collection:
[
{
"Id": 1,
"extension": [
{
"keyName": "Name",
"value": "Bob"
},
{
"keyAge": "Age",
"value": 20
}
]
},
{
"Id": 2,
"extension": [
{
"keyName": "Name",
"value": "Sam"
},
{
"key": "Name",
"value": "Sam"
}
]
},
{
"Id": 3,
"extension": [
{
"keyName": "Age",
"value": 25
},
{
"key": "Age",
"value": 25
}
]
},
{
"Id": 4
}
]
I would like to update any items in the extension array of all documents
so that when an item is found with a key property, to rename it keyAge.
Here is the expected result:
[
{
"Id": 1,
"extension": [
{
"keyName": "Name",
"value": "Bob"
},
{
"keyAge": "Age",
"value": 20
}
]
},
{
"Id": 2,
"extension": [
{
"keyName": "Name",
"value": "Sam"
},
{
"keyAge": "Name",
"value": "Sam"
}
]
},
{
"Id": 3,
"extension": [
{
"keyName": "Age",
"value": 25
},
{
"keyAge": "Age",
"value": 25
}
]
},
{
"Id": 4
}
]
I tried to use $rename in a similar way to this question:
MongoDB rename database field within array
but I get the same error $rename source may not be dynamic array
I think this solution might also apply to me, I tried using it but it's not updating anything on my side, so I guess I cannot understand how to apply that answer to me...
https://stackoverflow.com/a/49193743/215553
Thanks for the help!

Answer 1

I tried to use $rename in a similar way to this question: MongoDB rename database field within array but I get the same error $rename source may not be dynamic array
There is a note in $rename:
$rename does not work if these fields are in array elements.
You can try update with aggregation pipeline starting from MongoDB 4.2,
check condition id key field is exists
$map to iterate loop of extension array
$map to iterate loop of array that is converted from extension object to array in key-value format
$cond check condition if k is key then return keyAge otherwise return current
$arrayToObject back to convert key-value array return from above map to object original format
db.collection.update(
{ "extension.key": { $exists: true } },
[{
$set: {
extension: {
$map: {
input: "$extension",
in: {
$arrayToObject: {
$map: {
input: { $objectToArray: "$$this" },
in: {
k: {
$cond: [
{ $eq: ["$$this.k", "key"] }, // check "key" field name
"keyAge", // update new name "keyAge"
"$$this.k"
]
},
v: "$$this.v"
}
}
}
}
}
}
}
}],
{ multi: true }
)
Playground

Answer 2

Question : How to Rename or add new key for existing array object key?
Answer : Inside projection of mongodb query we have map property which will resolve this.
Solution Example :
{
parents: {
$map: {
input: "$parents",
as: "parent",
in: {
caaUserId: "$$parent._id",
email: "$$parent.email",
countryCode: "$$parent.countryCode",
mobile: "$$parent.mobile",
reportType : "single"
}
}
}
}
In this example if we want to rename $parent._id as caaUserId in parents array for each Element.
Then we can use map and define caaUserId like $$parent._id. This whole code will work in mongoose projection of Query.
It should return following :
{
"parents" : [
{
"caaUserId" : "62d17fa164057000149e283f",
"email" : "john.doe#hotmail.com",
"countryCode" : 91,
"mobile": 9876543210,
"reportType":"single",
},
{
"caaUserId" : "6195d50f15ae2b001293c486",
"email" : "akka.ash#hotmail.com",
"countryCode" : 91,
"mobile": 9876543211,
"reportType":"multi",
},
]
}

Answer 3

This is something that works in your case. Might not be the most readable though.
import json
data = json.loads(strdata)
for entry in data:
if 'extension' in entry:
for x in entry['extension']:
for k, v in x.items():
if k == 'key':
x['keyAge'] = x.pop(k)