#' @title
#' Enumerate the exported variables
#'
#' @description
#' This function calls the 'exportFieldNames' function of the
#' REDCap API.
#'
#' @param redcap_uri The
#' [uri](https://en.wikipedia.org/wiki/Uniform_Resource_Identifier)/url
#' of the REDCap server
#' typically formatted as "https://server.org/apps/redcap/api/".
#' Required.
#' @param token The user-specific string that serves as the password for a
#' project. Required.
#' @param verbose A boolean value indicating if `message`s 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.
#' @param config_options A list of options passed to [httr::POST()].
#' See details at [httr::httr_options()]. Optional.
#' @param handle_httr 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.
#'
#' @return
#' Currently, a list is returned with the following elements,
#' * `data`: A [tibble::tibble()] where each row represents one column
#' in the REDCap dataset.
#' * `success`: A boolean value indicating if the operation was apparently
#' successful.
#' * `status_code`: The
#' [http status code](https://en.wikipedia.org/wiki/List_of_HTTP_status_codes)
#' 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.
#'
#' @details
#' As of REDCap version 6.14.2, three variable types are *not* returned in
#' this call: calculated, file, and descriptive. All variables returned are
#' writable/uploadable.
#'
#' @author
#' Will Beasley
#'
#' @references
#' 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.
#'
#' @examples
#' \dontrun{
#' uri <- "https://bbmc.ouhsc.edu/redcap/api/"
#' token <- "9A81268476645C4E5F03428B8AC3AA7B"
#' ds_variable <- REDCapR::redcap_variables(redcap_uri=uri, token=token)$data
#' }
#' @export
redcap_variables <- function(
redcap_uri,
token,
verbose = TRUE,
config_options = NULL,
handle_httr = NULL
) {
checkmate::assert_character(redcap_uri, any.missing=FALSE, len=1, pattern="^.{1,}$")
checkmate::assert_character(token , any.missing=FALSE, len=1, pattern="^.{1,}$")
token <- sanitize_token(token)
verbose <- verbose_prepare(verbose)
post_body <- list(
token = token,
content = "exportFieldNames",
format = "csv"
)
# This is the important call that communicates with the REDCap server.
kernel <-
kernel_api(
redcap_uri = redcap_uri,
post_body = post_body,
config_options = config_options,
handle_httr = handle_httr
)
if (!kernel$success) {
if (is.null(kernel$raw_text)) {
# nocov start
rlang::abort(
message = "REDCapR::redcap_variables() encountered an error communicating with the server."
)
# nocov end
} else {
# nocov start
rlang::abort(
message = kernel$raw_text
)
# nocov end
}
} else {
try(
{
# Convert the raw text to a dataset.
ds <-
readr::read_csv(
file = I(kernel$raw_text),
show_col_types = FALSE
)
},
silent = TRUE
# Don't print the warning in the try block. Print it below, where
# it's under the control of the caller.
)
if (exists("ds") && inherits(ds, "data.frame")) {
outcome_message <- sprintf(
"%s variable metadata records were read from REDCap in %0.1f seconds. The http status code was %i.",
format(nrow(ds), big.mark = ",", scientific = FALSE, trim = TRUE),
kernel$elapsed_seconds,
kernel$status_code
)
kernel$raw_text <- ""
# If an operation is successful, the `raw_text` is no longer returned
# to save RAM. The content is not really necessary with httr's status
# message exposed.
} else {
# nocov start
kernel$success <- FALSE # Override the 'success' http status code.
ds <- tibble::tibble() # Return an empty data.frame
outcome_message <- sprintf(
"The REDCap variable retrieval failed. The http status code was %i. The 'raw_text' returned was '%s'.",
kernel$status_code,
kernel$raw_text
)
# nocov end
}
}
# } else {
# ds <- tibble::tibble() # Return an empty data.frame
# outcome_message <-
# if (any(grepl(kernel$regex_empty, kernel$raw_text))) {
# "The REDCapR read/export operation was not successful. The returned dataset (of variables) was empty." # nocov
# } else {
# sprintf(
# "The REDCapR variable retrieval was not successful. The error message was:\n%s",
# kernel$raw_text
# )
# }
# }
if (verbose)
message(outcome_message)
list(
data = ds,
success = kernel$success,
status_code = kernel$status_code,
outcome_message = outcome_message,
elapsed_seconds = kernel$elapsed_seconds,
raw_text = kernel$raw_text
)
}
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