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Fetch records for a REDCap project

Source: R/fetch_records.R
fetch_records.Rd

Execute an "Export Records" API request to fetch a tibble-style data frame containing records for one or more REDCap instruments.

Usage

fetch_records(
  conn,
  forms = NULL,
  events = NULL,
  records = NULL,
  records_omit = NULL,
  fields = NULL,
  id_field = TRUE,
  rm_empty = TRUE,
  rm_empty_omit_calc = FALSE,
  value_labs = TRUE,
  value_labs_fetch_raw = FALSE,
  header_labs = FALSE,
  checkbox_labs = FALSE,
  use_factors = FALSE,
  times_chron = TRUE,
  date_range_begin = NULL,
  date_range_end = NULL,
  fn_dates = parse_date,
  fn_dates_args = list(orders = c("Ymd", "dmY")),
  fn_datetimes = lubridate::parse_date_time,
  fn_datetimes_args = list(orders = c("Ymd HMS", "Ymd HM")),
  na = c("", "NA"),
  dag = TRUE,
  batch_size = 100L,
  batch_delay = 0.5,
  double_resolve = FALSE,
  double_remove = FALSE,
  double_sep = "--"
)

Arguments

conn

A REDCap API connection object (created with rconn)

forms

Character vector of forms (i.e. instruments) to fetch data for. Set to NULL (the default) to fetch all forms in the project.

events

Character vector of events to fetch. Must correspond to the selected forms. Set to NULL (the default) to fetch all events corresponding to the selected form(s).

records

Character vector of record IDs to fetch. Set to NULL (the default) to fetch all record IDs corresponding to the selected form(s).

records_omit

Character vector of record IDs to ignore. Set to NULL (the default) to not ignore any records. If a given record ID appears in both argument records and records_omit, argument records_omit takes precedence and that record will not be returned.

fields

Character vector of fields (i.e. variables) to fetch. Set to NULL (the default) to fetch all fields corresponding to the selected form(s).

id_field

Logical indicating whether to always include the 'record ID' field (defined in REDCap to be the first variable in the project codebook) in the API request, even if it's not specified in argument fields. Defaults to TRUE.

The record ID field is defined within the first form of a REDCap project, and so API requests for other forms will not include the record ID field by default (unless it's explicitly requested with argument fields). The id_field argument is a shortcut to avoid having to always explicitly request the record ID field.

rm_empty

Logical indicating whether to remove rows for which all fields from the relevant form(s) are missing. See section Removing empty rows. Defaults to TRUE.

rm_empty_omit_calc

Logical indicating whether to exclude calculated fields from assessment of empty rows. Defaults to FALSE. In some cases calculated fields can be autopopulated for certain records even when the relevant form is truly empty, which would otherwise lead to "empty" forms being returned even when rm_empty is TRUE. Defaults to FALSE.

value_labs

Logical indicating whether to return value labels (TRUE) or raw values (FALSE) for categorical REDCap variables (radio, dropdown, yesno, checkbox). Defaults to TRUE to return labels.

value_labs_fetch_raw

Logical indicating whether to request raw values for categorical REDCap variables (radio, dropdown, yesno, checkbox), which are then transformed to labels in a separate step when value_labs = TRUE. Primarily used for troubleshooting issues with the REDCap API returning fewer records than expected when given certain combinations of request parameters.

header_labs

Logical indicating whether to export column names as labels (TRUE) or raw variable names (FALSE). Defaults to FALSE to return raw variable names.

checkbox_labs

Logical indicating whether to export checkbox labels (TRUE) or statuses (i.e. "Unchecked" or "Checked") (FALSE). Defaults to FALSE to export statuses. Note this argument is only relevant when value_labs is TRUE — if value_labs is FALSE checkbox variables will always be exported as raw values (usually "0"/"1").

use_factors

Logical indicating whether categorical REDCap variables (radio, dropdown, yesno, checkbox) should be returned as factors. Factor levels can either be raw values (e.g. "0"/"1") or labels (e.g. "No"/"Yes") depending on arguments value_labs and checkbox_labs. Defaults to FALSE.

times_chron

Logical indicating whether to reclass time variables using chron::times (TRUE) or leave as character HH:MM format (FALSE). Defaults to TRUE. Note this only applies to variables of REDCap type "Time (HH:MM)", and not "Time (MM:SS)".

date_range_begin

Fetch only records created or modified after a given date-time. Use format "YYYY-MM-DD HH:MM:SS" (e.g., "2017-01-01 00:00:00" for January 1, 2017 at midnight server time). Defaults to NULL to omit a lower time limit.

date_range_end

Fetch only records created or modified before a given date-time. Use format "YYYY-MM-DD HH:MM:SS" (e.g., "2017-01-01 00:00:00" for January 1, 2017 at midnight server time). Defaults to NULL to omit a lower time limit.

fn_dates

Function to parse REDCap date variables. Defaults to parse_date, an internal wrapper to lubridate::parse_date_time. If date variables have been converted to numeric (e.g. by writing to Excel), set to e.g. lubridate::as_date to convert back to dates.

fn_dates_args

List of arguments to pass to fn_dates. Can set to empty list list() if using a function that doesn't take any arguments.

fn_datetimes

Function to parse REDCap datetime variables. Defaults to lubridate::parse_date_time.

fn_datetimes_args

List of arguments to pass to fn_datetimes. Can set to empty list list() if using a function that doesn't take any arguments.

na

Character vector of strings to interpret as missing values. Passed to readr::read_csv. Defaults to c("", "NA").

dag

Logical indicating whether to export the redcap_data_access_group field (if used in the project). Defaults to TRUE.

batch_size

Number of records to fetch per batch. Defaults to 100L. Set to Inf or NA to fetch all records at once.

batch_delay

Delay in seconds between fetching successive batches, to give the REDCap server time to respond to other requests. Defaults to 0.5.

double_resolve

Logical indicating whether to resolve double-entries (i.e. records entered in duplicate using REDCap's Double Data Entry module), by filtering to the lowest entry number associated with each unique record.

If a project uses double-entry, the record IDs returned by an "Export Records" API request will be a concatenation of the normal record ID and the entry number (1 or 2), normally separated by "–" (e.g. "P0285–1"). To resolve double entries we move the entry number portion of the ID to its own column (entry), identify all entries belonging to the same unique record, and retain only the row with the lowest entry number for each unique record.

Unique records are identified using the record ID column (after separating the entry number portion), and any of the following columns when present (accounting for argument header_labs): redcap_event_name (Redcap Event), redcap_repeat_instrument (Repeat Instrument), redcap_repeat_instance (Repeat Instance).

double_remove

Logical indicating whether to remove double-entries (i.e. records entered in duplicate using REDCap's Double Data Entry module), by filtering out records where the record ID field contains pattern double_sep (see next argument), so that only merged records remain.

double_sep

If double_resolve is TRUE, the string separator used to split the record ID field into the record ID and entry number. Defaults to "–".

Value

A tibble-style data frame containing the requested records

Removing empty rows

Depending on the database design, an "Export Records" API request can sometimes return empty rows, representing forms for which no data has been collected. For example, if forms F1 and F2 are part of the same event, and participant "P001" has form data for F2 but not F1, an API request for F1 will include a row for participant "P001" where all F1-specific fields are empty.

If argument rm_empty is TRUE (the default), fetch_records() will filter out such rows. The check for empty rows is based only on fields that are specific to the form(s) specified in argument forms — i.e. it excludes the record ID field, and generic fields like redcap_event_name, redcap_data_access_group, etc. The check for empty rows also accounts for checkbox fields, which, if argument checkbox_labs is FALSE, will be set to "Unchecked" in an empty form (rather than missing per se).

Examples

if (FALSE) { # \dontrun{
conn <- rconn(
  url = "https://redcap.msf.fr/api/",
  token = Sys.getenv("MY_REDCAP_TOKEN")
)

fetch_records(conn, forms = "my_form")
} # }