library(shiny)
ui <- fluidPage(
downloadButton('download')
)
server <- function(input, output) {
output$download <- downloadHandler(
filename = "listing.pdf",
content = function(f) {
# Create a new empty environment
# This allows us to pass in only the relevant variables into the report
e <- new.env()
# Pass two data sets into our template
e$datasets <- list(mtcars, iris)
# Render the document
rmarkdown::render('template.Rmd',
output_format = rmarkdown::pdf_document(),
output_file=f,
envir = e)
}
)
}
shinyApp(ui = ui, server = server)TL;DR here is an example application. See the explaination below.
A common issue I have run into is dynamically generating reports. In particular, during my summer at Novartis there was lots of demands for report listings that could be generated on the fly from a Shiny application. Using the great rmarkdown package makes it really easy to do this. My approach is to create a template R markdown file and dynamically generate it using rmarkdown::render in a download handler.
The full application is available here: https://github.com/stefaneng/Shiny-Dynamic-Report-Generation
We first need a R markdown template that we can use for the report generation. We want to print out some data set using the pander package to make nicer formatted tables.
---
title: "Example Template"
author: "Stefan Eng"
date: "8/7/2019"
output: pdf_document
---
```{r setup, include=FALSE}
library(knitr)
library(pander)
knitr::opts_chunk$set(echo = FALSE)
```
```{r, results='asis'}
panderOptions('knitr.auto.asis', FALSE)
for(d in datasets) {
pander::pander(d, split.table=120)
}
```To generate the report from Shiny, we use a downloadHandler and render the template using rmarkdown::render. This is called each time the user clicks the download button. In the full example on github, the user can select a data set to include in the report which is more realistic. The example given is the simplest to get you going on generating your own dynamic reports.
Reproducibility
─ Session info ───────────────────────────────────────────────────────────────────────────────────────────────────────
setting value
version R version 4.2.1 (2022-06-23)
os macOS Catalina 10.15.7
system x86_64, darwin17.0
ui X11
language (EN)
collate en_US.UTF-8
ctype en_US.UTF-8
tz America/Los_Angeles
date 2022-12-11
pandoc 2.19.2 @ /Applications/RStudio.app/Contents/MacOS/quarto/bin/tools/ (via rmarkdown)
─ Packages ───────────────────────────────────────────────────────────────────────────────────────────────────────────
! package * version date (UTC) lib source
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P rprojroot 2.0.3 2022-04-02 [?] CRAN (R 4.2.0)
P rstudioapi 0.14 2022-08-22 [?] CRAN (R 4.2.0)
P sessioninfo * 1.2.2 2021-12-06 [?] CRAN (R 4.2.0)
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P xfun 0.35 2022-11-16 [?] CRAN (R 4.2.0)
P yaml 2.3.6 2022-10-18 [?] CRAN (R 4.2.0)
[1] /Users/stefaneng/personal_devel/stefanengineering.comV3/renv/library/R-4.2/x86_64-apple-darwin17.0
[2] /Users/stefaneng/personal_devel/stefanengineering.comV3/renv/sandbox/R-4.2/x86_64-apple-darwin17.0/84ba8b13
P ── Loaded and on-disk path mismatch.
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