Learn R Programming

redcapAPI (version 2.0)

exportArms: Export the Arms for a Project

Description

This function allows you to export the Arms for a project Note: this only works for longitudinal projects

Usage

exportArms(rcon, ...)

# S3 method for redcapDbConnection exportArms(rcon, ...)

# S3 method for redcapApiConnection exportArms(rcon, arms = NULL, ..., error_handling = getOption("redcap_error_handling"))

Arguments

rcon

A REDCap connection object as generated by redcapConnection.

...

Arguments to be passed to other methods.

arms

A numeric vector or arm numbers to retrieve. In REDCap 6.5.0, using this argument results in an empty data frame being returned.

error_handling

An option for how to handle errors returned by the API. see redcap_error

Value

Returns a data frame with two columns

  • arm_num The arm number

  • name The arm's descriptive name

REDCap API Documentation

This function allows you to export the Arms for a project

NOTE: this only works for longitudinal projects.

REDCap Version

5.8.2+

Known REDCap Limitations

In versions earlier than 5.9.15, providing a value to the arms argument had no effect and the entire data frame of arms is returned.

This was fixed in version 5.9.15. Sometime before 6.5.0, using the arms argument resulted in empty data frames being returned.

In most cases, the number or arms is fairly small, so there is no real performance benefit to only selecting a subset of the arms. The safest course of action is to export all of the arms (the default behavior)

Details

It is not sufficient to make the project a longitudinal project. The project must satisfy one of two conditions: 1) have at least two arms and one event defined in each arm; or 2) have one arm and at least two events defined. If neither of these conditions are satisfied, the API will return a message such as ERROR: You cannot export arms for classic projects, an error message that isn't as descriptive of the nature of the problem as we might like.

References

Please refer to your institution's API documentation.

Additional details on API parameters are found on the package wiki at https://github.com/nutterb/redcapAPI/wiki/REDCap-API-Parameters