Export Arms of a REDCap project

  verbose = TRUE,
  config_options = NULL,
  handle_httr = NULL



The uri/url of the REDCap server typically formatted as "https://server.org/apps/redcap/api/". Required.


The user-specific string that serves as the password for a project. Required.


A boolean value indicating if messages should be printed to the R console during the operation. The verbose output might contain sensitive information (e.g. PHI), so turn this off if the output might be visible somewhere public. Optional.


A list of options passed to httr::POST(). See details at httr::httr_options(). Optional.


The value passed to the handle parameter of httr::POST(). This is useful for only unconventional authentication approaches. It should be NULL for most institutions. Optional.


Currently, a list is returned with the following elements:

  • has_arms: a logical value indicating if the REDCap project has arms (i.e., "TRUE") or is a classic non-longitudinal project (i.e., "FALSE").

  • data: a tibble::tibble() with one row per arm. The columns are arm_number (an integer) and arm_name (a human-friendly string).

  • success: A boolean value indicating if the operation was apparently successful.

  • status_code: The http status code of the operation.

  • outcome_message: A human readable string indicating the operation's outcome.

  • elapsed_seconds: The duration of the function.

  • raw_text: If an operation is NOT successful, the text returned by REDCap. If an operation is successful, the raw_text is returned as an empty string to save RAM.


The official documentation can be found on the 'API Help Page' and 'API Examples' pages on the REDCap wiki (i.e., https://community.projectredcap.org/articles/456/api-documentation.html and https://community.projectredcap.org/articles/462/api-examples.html). If you do not have an account for the wiki, please ask your campus REDCap administrator to send you the static material.


Will Beasley


# \dontrun{
uri            <- "https://bbmc.ouhsc.edu/redcap/api/"

# Query a classic project with 3 arms
token_1  <- "CDF9F3767E413FDBAA31D92E9F36730A"
result_1 <- REDCapR::redcap_arm_export(redcap_uri=uri, token=token_1)
#> The list of arms was retrieved from the REDCap project in 0.1 seconds. The http status code was 200.
#> [1] TRUE
#> # A tibble: 3 × 2
#>   arm_number arm_name
#>        <int> <chr>   
#> 1          1 Arm 1   
#> 2          2 Arm 2   
#> 3          3 Arm 3   

# Query a classic project without arms
token_2  <- "D70F9ACD1EDD6F151C6EA78683944E98"
result_2 <- REDCapR::redcap_arm_export(redcap_uri=uri, token=token_2)
#> A 'classic' REDCap project has no arms.  Retrieved in 0.1 seconds. The http status code was 400.
#> [1] FALSE
#> # A tibble: 0 × 2
#> # ℹ 2 variables: arm_number <int>, arm_name <chr>
# }