Provides the core Shiny server and UI hooks for collecting and downloading student answers
from a learnr tutorial. submission_server() should be called in an Rmd code chunk with
context="server".
This function was modified from Colin Rundel's learnrhash package (https://github.com/rundel/learnrhash).
UI block to include a download button and simple instructions for students.
Value
No return value; called for side effects in a Shiny/learnr session.
An object of class shiny.tag
Details
The server function uses a Shiny downloadHandler to let students download their answers.
All main logic must be wrapped in local() with parent.frame() to ensure access to the live
learnr session and objects created in the parent environment.
The session object (created by Shiny) is only available inside the downloadHandler$content
function, so any test-case extraction or answer writing must happen there.
For reference: the file argument in content is a temporary file path created by Shiny,
and your handler's job is to write the downloadable file there.
If you want to generate test fixtures, insert browser() inside the content function,
then use functions like get_submissions_from_learnr_session(session) at the prompt.
See also: https://mastering-shiny.org/action-transfer.html#downloading-reports
Examples
if(interactive()){
submission_server()
}
if(interactive()){
submission_ui
}