CODEWITHSUNDEEP
scalaplayframeworkreactivemongo
schub
schub

Reputation: 932

Problems executing reactivemongo aggregation framework query getting a DefaultJSONCommandError

I'm using reactivemongo with play framework. I used to have a query which uses the aggregation framework and it worked as expected. Since updated to version 0.13.0 I get errors executing the query.

The class looks like this:

class Foo(
  id: Option[UUID],
  obj: UUID,
  lm: Date
)

I want to give the query a list of UUIDs which match the obj property but only the latest according to lm property.

The result of that query should be mapped to a list of class Bar which looks like this:

class Bar(
  obj: UUID,
  ts: Date
)

The query looks like this (assuming col is a JSONCollection of the entity Foo and ids is a list of UUIDs.

import col.BatchCommands.AggregationFramework._

col
    .aggregate(
      Match(Json.obj("obj" -> Json.obj("$in" -> ids.map(_.toString)))),
      List(
        Sort(Descending("lm")),
        Group(JsString("$obj"))("obj" -> FirstField("obj"), "ts" -> FirstField("lm")),
        Project(Json.obj("_id" -> 0, "obj" -> "$obj", "ts" -> "$ts"))
      )
    )
    .map(_.head[Bar])

This worked as expected until the upgrade to 0.13.0. To be more precise I use the reactivemongo play plugin 0.13.0-play26

The error now looks like this:

play.api.http.HttpErrorHandlerExceptions$$anon$1: Execution exception[[DefaultJSONCommandError: CommandError[code=<unknown>, errmsg=<unknown>, doc: {"obj":"a797ec90-80d7-4b5e-b144-2454436f2b16","ts":1526390247074}]]]

Unfortunately, I could not find documentation on the reactivemongo website, it seems the docs have not been updated since 0.11.x

Using the mongo cli the query looks like this:

db.Foo.aggregate([{ $match: { obj: { $in: ["<uuid>", "<uuid>"] } } },{ $sort: { lm: -1 } },{ $group: { _id: "$obj", ts: { $first: "$ts" } } }]); and it gives me the correct result.

Can someone give me a hint, what I'm doing wrong here?

Upvotes: 2

Views: 371

Answers (1)

schub
schub

Reputation: 932

use col.aggregatorContext instead of col.aggregate

col
    .aggregatorContext[Bar](
      Match(Json.obj("obj" -> Json.obj("$in" -> ids.map(_.toString)))),
      List(
        Sort(Descending("lm")),
        Group(JsString("$obj"))("obj" -> FirstField("obj"), "ts" -> FirstField("lm")),
        Project(Json.obj("_id" -> 0, "obj" -> "$obj", "ts" -> "$ts"))
      )
    )
    .prepared
    .cursor
    .collect[List](-1, reactivemongo.api.Cursor.FailOnError[List[Bar]]())

Upvotes: 2

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