Querying REDCap database fails in targets pipeline

[Scott-Coggeshall]

I have data in a REDCap database that I want to pull into R via the REDCap API using the redcap_read function from the REDCapR package. If I run something like the following in a normal R session it works fine:

my_data <- REDCapR::redcap_read(redcap_uri = "https://fakeredcapdb.com/api/", token = "mytoken")

(with values for redcap_uri and token replaced by the actual uri and API token).

I want to do this within a targets plan like the following

library(targets)

tar_option_set(packages = c("REDCapR"))

list(
  tar_target(my_uri, "https://fakeredcapdb.com/api/", format = "url"),
  tar_target(my_token, "mytoken"),
  tar_target(data, redcap_read(redcap_uri = my_uri, token = my_token)))
)

However, running tar_make() results in the following error:

Error : HTTP response status code 501
Could not access url:
  https://fakeredcapdb.com/api/
HTTP response headers:
  cache-control = no-store, no-cache, must-revalidate
  pragma = no-cache
  content-length = 0
  content-type = text/xml; charset=utf-8
  expires = 0
  server = Microsoft-IIS/8.5
  x-xss-protection = 1; mode=block
  x-content-type-options = nosniff
  access-control-allow-origin = *
  x-powered-by = ASP.NET
  date = Thu, 02 Sep 2021 18:47:38 GMT

Do you have any idea why I'm able to access the url outside of a targets plan but not inside of one?

[wlandau]

format = "url" is for when you have a specific file in mind at a URL, e.g. https://raw.githubusercontent.com/wlandau/targets-minimal/main/data/raw_data.csv. For APIs, I would recommend something like:

tar_target(
  name = data,
  command = redcap_read(token = Sys.getenv("YOUR_TOKEN")),
  format = "feather" # assuming data frame format
  cue = tarchetypes::tar_cue_force(redcap_changed(Sys.getenv("YOUR_TOKEN")))
)

where redcap_changed() is a function you write to check if the remote database changed (using the last modified time stamp or hash of the database table). tarchetypes has a bunch of alternatives for this sort of thing, such as tar_change(), tar_age(), and tar_cue_age().

[Scott-Coggeshall]

Sorry for the late reply. This solved the issue, thanks!