Ivan “CLOVIS” Canet
@ivcanet.bsky.social
413 followers 348 following 1.3K posts
Kotlin developer & teacher @ 4SH, learn more about me: ivan.canet.dev Open source at opensavvy.dev • @opensavvy.techhub.social.ap.brid.gy Organizing the Kotlin Bordeaux User Group at bordeauxkt.io
 method which returns intermediate results:
```kotlin
users.aggregate()
.match { User::age gte 18 }
.sort { ascending(User::age) }
.limit(1)
.also { println(it.debug()) } // Temporarily add when debugging, or call using the debugger
.toList()
```
```terminaloutput
Pipeline debug (first 10 resulting documents after each stage):
Stage: {}
{"_id": {"$oid": "6aa304b526a3e786897e397a"}, "name": "Alice", "age": 30}
{"_id": {"$oid": "6aa304b526a3e786897e397b"}, "name": "Bob", "age": 17}
{"_id": {"$oid": "6aa304b526a3e786897e397c"}, "name": "Charlie", "age": 22}
Stage: {"$match": {"age": {"$gte": 18}}}
{"_id": {"$oid": "6aa304b526a3e786897e397a"}, "name": "Alice", "age": 30}
{"_id": {"$oid": "6aa304b526a3e786897e397c"}, "name": "Charlie", "age": 22}
Stage: {"$sort": {"age": 1}}
{"_id": {"$oid": "6aa304b526a3e786897e397c"}, "name": "Charlie", "age": 22}
{"_id": {"$oid": "6aa304b526a3e786897e397a"}, "name": "Alice", "age": 30}
Stage: {"$limit": 1}
{"_id": {"$oid": "6aa304b526a3e786897e397c"}, "name": "Charlie", "age": 22}
```
If a stage throws an exception, the debug method will say which one explicitly.](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:v5d32e7ctst5trrzjaztzuyo/bafkreifcasujwmr62xlabzrhminknmmw226yig4q5jnfh5r7mtle3qkkdq)
![pipeline.aggregate()
.set {
User::profiles[0] set User::profiles[1]
}
This writes the profile at index 1 into the profile at index 0, for every user
you'd think this symmetry would remain in BSON, but nooooo
[
{
$set: {
"profiles.0": {
$arrayElemAt: {
"$profiles",
{ $literal: 1 }
}
}
}
}
]](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:v5d32e7ctst5trrzjaztzuyo/bafkreiguk2rzwl5isbqnivy5eyrr2ama7m6glbpmsrb2pwnibzascvlh4a)
![// {
// $lookup: {
// from: "comments",
// localField: "_id",
// foreignField: "movie_id",
// let: { movie_year: "$year" },
// pipeline: [
// { $match: { $expr: { $gt: [ { $year: "$date" }, "$$movie_year" ] } } },
// ],
// as: "post_release_comments"
// }
// },
.lookup {
into(Movie::post_release_comments)
val movieYear = let(Movie::year)
from(
allComments
.matchExpr { Comment::year gt movieYear }
)
on(Movie::_id, Comment::movieId)
}](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:v5d32e7ctst5trrzjaztzuyo/bafkreifwtzvciyfe2k6hadyong6emtjb4fy7ydbp2hxjnaayxn76sheeju)
![The image shows garbled terminal output:
INFO - [07:41:56] Serving on http://0.0.0.0:8000/
2026-07-11T07:42:06.181474582Z WARNING - [07:42:06] " üé¡ 7óÈ@a?¥dÖòÂä<XüNëËÞZ}}+ Väû1ø" code 400
2026-07-11T07:42:06.182325954Z WARNING - [07:42:06] " üæ EÀÇwíÂhÖ2&:`Æë¤dq·¶7 ·Q!T s}@ð¿Çõ=¸Ñp" code 400](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:v5d32e7ctst5trrzjaztzuyo/bafkreiemwyiuqay7zzvngmaozkneheutyz7vzid62re3ckbnxqq3avaxii)
