MongoDB - Modify the field name in a nested list of lists - mongodb

Question

As the title says, the field I need to modify is nested like this:
basicData.owners.relatedJson.basicData.devices.equipmentID
which owners and devices are both lists.
The object looks like this:
{
"basicData": {
"owners": [
{
"relatedJson": {
"basicData": {
"devices": [
{
"equipmentID": "abcd",
"type": "camera"
}
],
"otherFieldsBasicData": "other values",
"evenMoreFieldsBasicData": "other values"
},
"otherFieldsRelatedJson": "other values",
"evenMoreFieldsRelatedJson": "other values"
}
}
]
}
}
I want to rename equipmentID to equipmentId.
I've also asked this question, and I've been trying to create a query using that as a starting point, but with no success.
I was able to build a query that could get as far down as the devices list, but. then I wanted to call $set on that list, and I get an error because you can't call set inside $mergeObjects.
I thought there was some way I could use $[] to help iterate through the first array, but I can't get it to work. I think this approach is wrong.
This is what I've ended up with, which doesn't work:
db.myCollection.updateMany({"basicData.owners.relatedJson.basicData.devices.equipmentID": {$exists: true}},
[
{
$set: {
"basicData.owners$[].relatedJson.basicData.devices": {
$map: {
input: "$basicData.owners$[].relatedJson.basicData.devices", in: {
$mergeObjects: ["$$this",
{equipmentId: "$$this.equipmentID",}]
}
}
}
}
},
{
$unset: "basicData.owners.relatedJson.basicData.devices.equipmentID"
}
])
Any advice would be greatly appreciated.

Answer 1

Think you need two $map (with nested) operators.
First $map to iterate basicData.owners array while another $map is used to iterate relatedJson.basicData.devices array.
db.collection.updateMany({
"basicData.owners.relatedJson.basicData.devices.equipmentID": {
$exists: true
}
},
[
{
$set: {
"basicData.owners": {
$map: {
input: "$basicData.owners",
in: {
$mergeObjects: [
"$$this",
{
"relatedJson": {
$mergeObjects: [
"$$this.relatedJson",
{
"basicData": {
$mergeObjects: [
"$$this.relatedJson.basicData",
{
"devices": {
$map: {
input: "$$this.relatedJson.basicData.devices",
in: {
$mergeObjects: [
"$$this",
{
equipmentId: "$$this.equipmentID",
}
]
}
}
}
}
]
}
}
]
}
}
]
}
}
}
}
},
{
$unset: "basicData.owners.relatedJson.basicData.devices.equipmentID"
}
])
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