Hi all,
I have the following query, which has multiple $cond and $ne functions:
db.collection.updateMany({
"basicData.owners.relatedJson.basicData.devices.equipmentID": {
$exists: true
}
},
[
{
$set: {
"basicData.owners": {
$map: {
input: "$basicData.owners",
in: {
$mergeObjects: [
"$$this",
{
$cond: [
{
$ne: [
"$$this.relatedJson",
undefined
]
},
{
"relatedJson": {
$mergeObjects: [
"$$this.relatedJson",
{
$cond: [
{
$ne: [
"$$this.relatedJson.basicData",
undefined
]
},
{
"basicData": {
$mergeObjects: [
"$$this.relatedJson.basicData",
{
$cond: [
{
$ne: [
"$$this.relatedJson.basicData.devices",
undefined
]
},
{
"devices": {
$map: {
input: "$$this.relatedJson.basicData.devices",
in: {
$mergeObjects: [
"$$this",
{
equipmentId: "$$this.equipmentID",
}
]
}
}
}
},
{},
]
}
]
}
},
{},
]
}
]
}
},
{},
]
}
]
}
}
}
}
},
{
$unset: "basicData.owners.relatedJson.basicData.devices.equipmentID"
}
])
This query works mostly as expected. However, I noticed that if an object exists but has a value of null, say relatedJson in the above example then this update will create an empty relatedJson value instead of leaving it null.
This situation can arise if for example there is one owner in the owners list that satisfies the query filter, but there are others that don’t.
How can I modify the $cond functions to exclude undefined and null objects?
I was thinking I could use the $in function somehow, but I can’t get it to work.
Anyone got any ideas?
Many thanks,
Paul.