MongoDB: Search by field with date and update it by condition - mongodb

Question

Please tell me how can I fulfill the following condition - if the time in the info.startDate field is not equal to 00 hours, increase the date (2021-05-27) by 1 day ahead, set the time to 00:00:00.000Z. I tried to do it clumsily, through Mongock, getting all the elements of the collection and doing a check through LocalDateTime, but my heap overflowed, which is logical because the collection is large. How can I do this through Mongock or at least a manual request to MongoDB. So far I've only written this:
db.getSiblingDB("ervk_core").getCollection("supervision").updateMany(
{},
[
{
"$set": {
"info.startDate": {
"$cond": {
if: {
$eq: [
"$info.startDate",
(there should be a condition at midnight)
]
},
then: (here the day should be added to full and the time should be set to midnight)
}
}
}
}
])
I would like to use dateToString to do a partial search by hour, but as I understand it, this function can only be used in an aggregation.
I would be grateful for your help :)

Answer 1

If you're using Mongo version 5.0+ then you can use $dateTrunc and $dateAdd to achieve this quite easily, like so:
db.collection.updateMany(
{},
[
{
$set: {
"info.startDate": {
$cond: [
{
$ne: [
{
$hour: "$info.startDate"
},
0
]
},
{
$dateTrunc: {
date: {
$dateAdd: {
startDate: "$info.startDate",
unit: "day",
amount: 1
}
},
unit: "day",
}
},
"$info.startDate"
]
}
}
}
])
For older Mongo versions this is slightly messier, you should use $dateFromParts to create the new date object, like so:
db.collection.updateMany(
{},
[
{
$set: {
"info.startDate": {
$cond: [
{
$ne: [
{
$hour: "$info.startDate"
},
0
]
},
{
$dateFromParts: {
"year": {
$year: {
$add: [
"$info.startDate",
86400000
]
}
},
"month": {
$month: {
$add: [
"$info.startDate",
86400000
]
}
},
"day": {
$dayOfMonth: {
$add: [
"$info.startDate",
86400000
]
}
},
"hour": 0,
"minute": 0,
"second": 0,
"millisecond": 0,
}
},
"$info.startDate"
]
}
}
}
])
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