NODE JS + Mongodb aggregation pipelines from MongoCharts - mongodb

Question

Currently can't figure out why one pipeline works and the other doesn't. I got both pipelines from MongoDB charts and they both returned something and displaying charts on MongoDBCharts. However, when I use them in my code, only the first pipeline returns something. I used the same data for all cases. Any suggestions would be greatly appreciated!
The first one doesn't filter the last 30 days (hard coded by Mongo), both pipelines are copied from Mongodb charts and are not altered.
[
{
"$addFields": {
"trigger_time": {
"$convert": {
"input": "$trigger_time",
"to": "date",
"onError": null
}
}
}
},
{
"$match": {
"event_type": {
"$nin": [
null,
"",
"AC Lost",
"Device Lost",
"logged into Database",
"logged into Nexus Database",
"logged out of Nexus Database",
"Low Battery"
]
}
}
},
{
"$addFields": {
"trigger_time": {
"$cond": {
"if": {
"$eq": [
{
"$type": "$trigger_time"
},
"date"
]
},
"then": "$trigger_time",
"else": null
}
}
}
},
{
"$addFields": {
"__alias_0": {
"hours": {
"$hour": "$trigger_time"
}
}
}
},
{
"$group": {
"_id": {
"__alias_0": "$__alias_0"
},
"__alias_1": {
"$sum": 1
}
}
},
{
"$project": {
"_id": 0,
"__alias_0": "$_id.__alias_0",
"__alias_1": 1
}
},
{
"$project": {
"y": "$__alias_1",
"x": "$__alias_0",
"_id": 0
}
},
{
"$sort": {
"x.hours": 1
}
},
{
"$limit": 5000
}
]
The second one
[
{
"$addFields": {
"trigger_time": {
"$convert": {
"input": "$trigger_time",
"to": "date",
"onError": null
}
}
}
},
{
"$match": {
"event_type": {
"$nin": [
null,
"",
"AC Lost",
"Device Lost",
"logged into Database",
"logged into Nexus Database",
"logged out of Nexus Database",
"Low Battery"
]
},
"trigger_time": {
"$gte": {
"$date": "2021-03-29T08:35:47.804Z"
}
}
}
},
{
"$addFields": {
"trigger_time": {
"$cond": {
"if": {
"$eq": [
{
"$type": "$trigger_time"
},
"date"
]
},
"then": "$trigger_time",
"else": null
}
}
}
},
{
"$addFields": {
"__alias_0": {
"hours": {
"$hour": "$trigger_time"
}
}
}
},
{
"$group": {
"_id": {
"__alias_0": "$__alias_0"
},
"__alias_1": {
"$sum": 1
}
}
},
{
"$project": {
"_id": 0,
"__alias_0": "$_id.__alias_0",
"__alias_1": 1
}
},
{
"$project": {
"y": "$__alias_1",
"x": "$__alias_0",
"_id": 0
}
},
{
"$sort": {
"x.hours": 1
}
},
{
"$limit": 5000
}
]

Answer 1

I end up solving my own problem. After a bit of digging and asking.
Node.js does some funny things with Mongodb when it comes to using '$date', that's why the pipeline didn't work.
The resolve was to remove '$date' and pass in a date object. For my case,
"trigger_time": {
"$gte": new Date("2021-03-29T08:35:47.804Z")
}