Unnecessary boxing of objects making mongolite queries invalid

[nimame]

@jeroen suggested the following approach to build a mongolite query using jsonlite here:

query <- list(TIMESTAMP = list("$gte" =  as.POSIXct("2015-01-01")))
str <- jsonlite::toJSON(query, auto_unbox=TRUE, POSIXt = "mongo")

However, I get the follwing for str: {"TIMESTAMP":{"$gte":[{"$date":1420070400000}]}} (using jsonlite 1.5 on R 3.4.0) and the brackets around the "$date" object make the query invalid. I don't see a way of getting rid of them using jsonlite::toJSON. Is this a bug?

[yutannihilation]

fromJSON() also seems weird when there's only one $date object (though this is a rare case.)

library(jsonlite)

fromJSON('{"a": 1}')
#> $a
#> [1] 1
fromJSON('{"a": {"$date": 1549446556000}}')
#> [1] "2019-02-06 18:49:16 JST"
fromJSON('{"a": {"$date": 1549446556000}, "b": 2}')
#> $a
#> [1] "2019-02-06 18:49:16 JST"
#> 
#> $b
#> [1] 2

^{Created on 2019-02-06 by the reprex package (v0.2.1.9000)}