R : Updating an entry in mongodb using mongolite - r

Question

I have a mongo database with information that I am passing to some R scripts for analysis. I am currently using the mongolite package to pass the information from mongo to R.
I have a field in each mongo entry called checkedByR, which is a binary that indicates whether the entry has been analysed by the R scripts already. Specifically, I am collecting a mongo entry by its respective mongo ID, running the scripts on the entry, assigning the checkedByR field with a 1, and then moving on.
For completeness, I am querying the database with the following request:
library(mongolite)
mongoID <- "1234abcd1234abcd1234"
m <- mongolite::mongo(url = "mongodb://localhost:27017",
collection = "collection",
db = "database")
rawData <- m$find(query = paste0('{"_id": { "$oid" : "',mongoID,'" }}'),
fields = '{"_id" : 1,
"checkedByR" : 1,
"somethingToCheck" : 1}')
checkedByR <- 1
However, I am having trouble successfully updating the mongo entry with the new checkedByR field.
I realise that an update function exists in the mongolite package (please consider : https://cran.r-project.org/web/packages/mongolite/mongolite.pdf), but I am having trouble gathering relevant examples to help me complete the updating process.
Any help would be greatly appreciated.

Answer 1

the mongo$update() function takes a query and a update argument. You use the query to find the data you want to update, and the update to tell it which field to update.
Consider this example
library(mongolite)
## create some dummy data and insert into mongodb
df <- data.frame(id = 1:10,
value = letters[1:10]
)
mongo <- mongo(collection = "another_test",
db = "test",
url = "mongodb://localhost")
mongo$insert(df)
## the 'id' of the document I want to update
mongoID <- "575556825dabbf2aea1d7cc1"
## find some data
rawData <- mongo$find(query = paste0('{"_id": { "$oid" : "',mongoID,'" }}'),
fields = '{"_id" : 1,
"id" : 1,
"value" : 1}'
)
## ...
## do whatever you want to do in R...
## ...
## use update to query on your ID, then 'set' to set the 'checkedByR' value to 1
mongo$update(
query = paste0('{"_id": { "$oid" : "', mongoID, '" } }'),
update = '{ "$set" : { "checkedByR" : 1} }'
)
## in my original data I didn't have a 'checkedByR' value, but it's added anyway
Update
the rmongodb library is no longer on CRAN, so the below code won't work
And for more complex structures & updates you can do things like
library(mongolite)
library(jsonlite)
library(rmongodb) ## used to insert a non-data.frame into mongodb
## create some dummy data and insert into mongodb
lst <- list(id = 1,
value_doc = data.frame(id = 1:5,
value = letters[1:5],
stringsAsFactors = FALSE),
value_array = c(letters[6:10])
)
## using rmongodb
mongo <- mongo.create(db = "test")
coll <- "test.another_test"
mongo.insert(mongo,
ns = coll,
b = mongo.bson.from.list(lst)
)
mongo.destroy(mongo)
## update document with specific ID
mongoID <- "5755f646ceeb7846c87afd90"
## using mongolite
mongo <- mongo(db = "test",
coll = "another_test",
url = "mongodb://localhost"
)
## to add a single value to an array
mongo$update(
query = paste0('{"_id": { "$oid" : "', mongoID, '" } }'),
update = '{ "$addToSet" : { "value_array" : "checkedByR" } }'
)
## To add a document to the value_array
mongo$update(
query = paste0('{"_id": { "$oid" : "', mongoID, '" } }'),
update = '{ "$addToSet" : { "value_array" : { "checkedByR" : 1} } }'
)
## To add to a nested array
mongo$update(
query = paste0('{"_id": { "$oid" : "', mongoID, '" } }'),
update = '{ "$addToSet" : { "value_doc.value" : "checkedByR" } }'
)
rm(mongo); gc()
see mongodb update documemtation for further details