Failed to authenticate credentials using Mongolite R - r

Question

I use R and trying to use the very recent "Mongolite". However I cannot connect to MongoDB server.
The manual clearly states the following:
mongo(collection = "test", db = "test", url = "mongodb://localhost")
This is what I have tried without success, where I have a log token and the port of course.
mongodb://heroku:TOKEN#lennon.mongohq.com:PORT
and keep getting the following error:
Error in mongo_collection_new(url, db, collection) :
Failed to authenticate credentials.

Answer 1

It is tried and true that mongolite (v0.7 as of today) supports authenticated connection to a remote 3.2.x MongoDB (as opposed to localhost).
The example below jeroenooms provides himself worked:
library(mongolite)
mongo(collection = "mtcars", url = "mongodb://readwrite:test#ds043942.mongolab.com:43942/jeroen_test")
To explain:
mtcars is the name of the MongoDB "collection" (or "table" if you insist). It could be a name that does not exist yet.
readwrite is the user name of your mongodb
test is the password of the user "readwrite"
ds043942.mongolab.com is the remote host, which could be replaced by ip address, i.e. 23.20.234.21
43942 is the port number. By default in MongoDB, it is 27017
jeroen_test is the name of the database instance in use, which has to exist already
Running the commands above in R will print:
Mongo Message: SCRAM: authenticating "readwrite" (step 1)
Mongo Message: SCRAM: authenticating "readwrite" (step 2)
Mongo Message: SCRAM: authenticating "readwrite" (step 3)
Mongo Message: SCRAM: "readwrite" authenticated
...
I tried to replace it with my own remote host info. It didn't work in the beginning, which turned to be the user role issue rather than mongolite issue. After ensuring a user with correct readWrite roles, I connected to my remote 3.2.x MongoDB via mongolite package.
The following 2 sources were of great help to me in setting up users in MongoDB:
enable-authentication
Manage User and Roles

Answer 2

If you look into the source code of jeroenooms/mongolite you can see that it doesn't support authentication yet:
https://github.com/jeroenooms/mongolite/blob/master/R/mongo.R
mongo_collection_new <- function(uri = "mongodb://localhost", db = "test", collection = "test"){
stopifnot(is.character(uri))
stopifnot(is.character(db))
stopifnot(is.character(collection))
.Call(R_mongo_collection_new, uri, db, collection)
}

Answer 3

just change the order :
mongo( url = "mongodb://localhost",db = "test",collection = "test")

Answer 4

I found that the following command allowed me to connect to mongodb using mongolite and the legacy SCRAM-SHA-1 authentication mode.
library(mongolite)
mongoUrl <- "mongodb://a_username:a_password#localhost:27017/admin" #<-admin here is the mongodb database that stores the authentication info
# specify your collection
colname <- "a_collection"
# specify your database
dbname <- "a_database"
# create connection (con)
con <- mongo(collection = colname, url = mongoUrl, db=dbname)
# count how many records (fyi this is just a test)
con$count('{}')