Rendering files in temporary environments inside Shiny applications

[jzkindness]

I'm trying to build a Shiny app which allows users to generate parameterised .Rmd documents based on their inputs. To generate the report, I first copy the report file to a temporary directory, before rendering the file in a new environment. My issue is that my Rmd document relies on other files - images and an .Rda file, which cannot be accessed in these empty environments and I have not found a way to copy them to the temporary directory or new environment. I need these files to be available when the .Rmd document is rendered with render(). Any suggestions?

 output$generate <- downloadHandler(filename = "examplereport.html",
    content = function(file) {
     tempReport <- file.path(tempdir(), "report.Rmd")
     file.copy("examplereport.Rmd", tempReport, overwrite = TRUE)
  
     params <- list(parameter1 = input$1, parameter2 = input$2, parameter3 = input$3)
      rmarkdown::render(tempReport, 
        output_file = file,
                      params = params,
                        envir = new.env(parent = globalenv())
      )
    }
  )```

[AlexisW]

Wouldn't it work to create the tempdir and copy the required files?

my_tempdir <- tempdir()

path_report <- paste0(my_tempdir, "/examplereport.Rmd")
path_rda <- paste0(my_tempdir, "/file_we_need.rda")

file.copy("examplereport.Rmd", path_report)
file.copy("templates/file_we_need.rda", path_rda)

initial_dir <- getwd()
setwd(my_tempdir)

rmarkdown::render(path_report, 
        output_file = file,
                      params = params,
                        envir = new.env(parent = globalenv())

setwd(initial_dir)

And same way, you could define the environment beforehand, manipulate it as needed, then pass it to render().