使用 rmongodb 时，在 mongoDB 中无法看到集合

Question

I am having the same issue as in this thread: Unable to see collections in mongo DB when connected through R

I am successfully connected to mongoDB.

> mongo.is.connected(mongo)
[1] TRUE

If I run the following code, I see the correct db.

> mongo.get.databases(mongo)
[1] "FF"
> 

But, when I try to view the collections, it returns character(0)

> mongo.get.database.collections(mongo , db = "FF")
character(0)
>

If I connect from the shell I can see all the collections, so I know they exist.

> use FF
switched to db FF

> show collections
kelp_classifications
kelp_groups
kelp_subjects
kelp_users

Answer 1

Update 2017-09-25

rmongodb is no longer supported and removed from CRAN

Reference: https://github.com/dselivanov/rmongodb

---

This function is working correctly for me in v1.8.0 :

mongo <- mongo.create()
mongo.is.connected(mongo)
# [1] TRUE
db <- "test"
mongo.get.database.collections(mongo, db = db)
[1] "test.test"

Answer 2

The following code seems to work in situations where mongo.get.database.collections(mongo, db = db) results in character(0)

mongo = mongo.create(host = "127.0.0.1:9997", db = "restaurant")

# Create a mongo.bson object with header as "listCollections", which is 
# a mongo DB command
command = list(listCollections = "") 
command = mongo.bson.from.list(command)
command
>listCollections : 2     

# calling mongo DB server to return collections as mongo.bson object
collections = mongo.command(mongo, "restaurant", command)

# convert mongo.bson object to a list 
collections = mongo.bson.to.list(collections)