CODEWITHSUNDEEP
rapi
Jdev
Jdev

Reputation: 110

how to retrieve data from a web server using an oauth2 token in R?

I've successfully received an access token from an oauth2.0 request so that I can start obtaining some data from the server. However, I keep getting error 403 on each attempt. APIs are very new to me and I only am entry level in using R so I can't figure out whats wrong with my request. I'm using the crul package currently, but I've tried to make the request with the httr package as well, but I can't get anything through without encountering the 403 error. I have a shiny app which in the end I'd like to be able to refresh with data imported from this other application which actually stores data, but I want to try to pull data to my console locally first so I can understand the basic process of doing so. I will post some of my current attempts. 

(x <- HttpClient$new(
url = 'https://us.castoredc.com',
opts = list( exceptions = FALSE),
headers = list())
)
res.token <- x$post('oauth/token',
body = list(client_id = "{id}",
client_secret = "{secret}",
grant_type = 'client_credentials'))

importantStuff <- jsonlite::fromJSON(res$parse("UTF-8"))

token <- paste("Bearer", importantStuff$access_token)

I obtain my token, but the following doesn't seem to work.### I'm attempting to get the list of study codes so that I can call on them in further requests to actually get data from a study.

res.studies <- x$get('/api/study',headers = list(Authorization = 
token,client_id = "{id}",
client_secret = "{secret}",
grant_type = 'client_credentials'),
body = list(
content_type = 'application/json'))

Their support team gave me the above endpoint to access the content, but I get 403 so I think i'm not using my token correctly? 

status: 403
access-control-allow-headers: Authorization
access-control-allow-methods: Get,Post,Options,Patch

Upvotes: 1

Views: 624

Answers (3)

Danny Cao
Danny Cao

Reputation: 47

This worked for me, I removed the Sys.getenv() part

library(castoRedc)
castor_api <- CastorData$new(key = "CASTOR_KEY", 
                             secret = "CASTOR_SECRET", 
                             base_url = "https://data.castoredc.com")
example_study_id <- studies[["study_id"]][1]
fields <- castor_api$getFields(example_study_id)

Upvotes: 1

Derk Arts
Derk Arts

Reputation: 3460

I'm the CEO at Castor EDC and although its pretty cool to see a Castor EDC question on here, I apologize for the time you lost over trying to figure this out. Was our support team not able to provide more assistance?

Regardless, I have actually used our API quite a bit in R and we also have an amazing R Engineer in house if you need more help.

Reflecting on your answer, yes, you always need a Study ID to be able to do anything interesting with the API. One thing that could make your life A LOT easier is our R API wrapper, you can find that here: https://github.com/castoredc/castoRedc

With that you would:

remotes::install_github("castoredc/castoRedc")
library(castoRedc)
castor_api <- CastorData$new(key = Sys.getenv("CASTOR_KEY"), 
                             secret = Sys.getenv("CASTOR_SECRET"), 
                             base_url = "https://data.castoredc.com")
example_study_id <- studies[["study_id"]][1]
fields <- castor_api$getFields(example_study_id)

etc.

Hope that makes you life a lot easier in the future.

Upvotes: 4

Jdev
Jdev

Reputation: 110

So, After some investigation, It turns out that you first have to make a request to obtain another id for each Castor study under your username. I will post some example code that worked finally.

req.studyinfo <- httr::GET(url = "us.castoredc.com/api/study"
,httr::add_headers(Authorization = token))
json <- httr::content(req.studyinfo,as = "text")
studies <- fromJSON(json)

Then, this will give you a list of your studies in Castor for which you can obtain the ID that you care about for your endpoints. It will be a list that contains a data frame containing this information. you use the same format with whatever endpoint you like that is posted in their documentation to retrieve data. Thank you for your observations! I will leave this here in case anyone is employed to develop anything from data used in the Castor EDC. Their documentation was vague to me, so maybe it will help someone in the future. Example for next step:

req.studydata <- httr::GET("us.castoredc.com/api/study/{study id obtained 
from previous step}/data-point- 
collection/study",,httr::add_headers(Authorization = 
token))
json.data <- httr::content(req.studydata,as = "text")
data <- fromJSON(json.data)

Upvotes: 1

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