Mongolite and R

Question

I have the code below, why it is not working? Thanks.

library(mongolite)
library(jsonlite)

id <- c('35325073','35325078')

id_list_JSON <- toJSON(id)

test3 <- m1$find('{"_id": {"$in": id_list_JSON}}', fields = '{"_id" : 1, "f.fid" : 1, "ud" : 1}')

Error: Invalid JSON object: {"_id": {"$in": id_list_JSON}}

Answer 1

@Marc B is correct in that you have to build the string to use the values contained in id_list_JSON.

In R you can use paste0 to do this

test3 <- m1$find(paste0('{"_id": {"$in": ', id_list_JSON, '}}'), 
                 fields = '{"_id" : 1, "f.fid" : 1, "ud" : 1}')

Where the paste0 line gives

paste0('{"_id": {"$in": ', id_list_JSON, '}}')

# "{\"_id\": {\"$in\": [\"35325073\",\"35325078\"]}}"

Which should then work in your query.