Saving rmarkdown output locally from Shiny - r

Question

I have a shiny app that generates a downloadable report using rmarkdown, which works fine. I would like a copy of the report to be saved on the shiny host each time a user uploads data to generate a report. Ideally, I'd like to do this from within the downloadHandler call so that I do not have to generate the report twice.
A minimal example (adapted from this shiny article):
library(shiny)
shinyApp(
ui = fluidPage(
sliderInput("slider", "Slider", 1, 100, 50),
downloadButton("report", "Generate report")
),
server = function(input, output) {
output$report <- downloadHandler(
# For PDF output, change this to "report.pdf"
filename = "report.html",
content = function(file) {
# Copy the report file to a temporary directory before processing it, in
# case we don't have write permissions to the current working dir (which
# can happen when deployed).
tempReport <- file.path(tempdir(), "report.Rmd")
file.copy("report.Rmd", tempReport, overwrite = TRUE)
# Set up parameters to pass to Rmd document
params <- list(n = input$slider)
# Knit the document, passing in the `params` list, and eval it in a
# child of the global environment (this isolates the code in the document
# from the code in this app).
rmarkdown::render(tempReport, output_file = file,
params = params,
envir = new.env(parent = globalenv())
)
}
)
}
)
The rmarkdown file
---
title: "Dynamic report"
output: html_document
params:
n: NA
---
```{r}
# The `params` object is available in the document.
params$n
```
A plot of `params$n` random points.
```{r}
plot(rnorm(params$n), rnorm(params$n))
```

Answer 1

You basically just need to copy the generated report into another directory. Here is an example based on the code you gave.
library(shiny)
if(!dir.exists("reportDir"))
dir.create("reportDir")
shinyApp(
ui = fluidPage(
sliderInput("slider", "Slider", 1, 100, 50),
downloadButton("report", "Generate report")
),
server = function(input, output) {
output$report <- downloadHandler(
# For PDF output, change this to "report.pdf"
filename = "report.html",
content = function(file) {
# Copy the report file to a temporary directory before processing it, in
# case we don't have write permissions to the current working dir (which
# can happen when deployed).
tempReport <- file.path(tempdir(), "report.Rmd")
file.copy("report.Rmd", tempReport, overwrite = TRUE)
# Set up parameters to pass to Rmd document
params <- list(n = input$slider)
# Knit the document, passing in the `params` list, and eval it in a
# child of the global environment (this isolates the code in the document
# from the code in this app).
rmarkdown::render(tempReport, output_file = file,
params = params,
envir = new.env(parent = globalenv())
)
# copy generated report
file.copy(file, paste("reportDir/", Sys.time(), ".html"))
}
)
}
)