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.
MongoDB's update() and save() methods are used to update document into a collection. The update() method updates the values in the existing document while the save() method replaces the existing document with the document passed in save() method.
MongoDB Update method is used to update the document from the collection, and the update method will update the value of the existing document. We have used a $set operator at the time of updating the document. We can update a single document by using an update or updateOne method.
the mongo$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
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
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