Attach a knitted tempfile to email in R shiny - r

Question

I have a working shiny app that uses Mailgun to send an email when a button is clicked and also produces a rmarkdown report when another button is clicked.
Here is working code, obviously without the working email authentication:
ui.R
library(shiny)
# Define UI for application that draws a histogram
shinyUI(fluidPage(
sliderInput("slider", "Slider", 1, 100, 50),
downloadButton("report", "Generate report"),
actionButton("mail", "send email"),
textOutput('mailo')
)
)
server.R
library(shiny)
sendEmail <- function(email = "xxx#you.org",
mail_message = "Hello"){
url <- "https://api.mailgun.net/v3/sandboxxxxxxxxx.mailgun.org/messages"
## username:password so api_key is all after the api:
api_key <- "key-0xxxxxxxxxxxx"
the_body <-
list(
from="Mailgun Sandbox <postmaster#sandboxxxxxxxxxxxxxxxx.mailgun.org>",
to=email,
subject="Mailgun from R test",
text=mail_message
)
req <- httr::POST(url,
httr::authenticate("api", api_key),
encode = "form",
body = the_body)
httr::stop_for_status(req)
TRUE
}
# Define server logic required to draw a histogram
shinyServer(function(input, output) {
event <- observeEvent(input$mail,{
sendEmail()
}, ignoreInit = TRUE)
output$mailo <- renderText({print("EMAIL SENT!")})
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())
)
}
)
})
I want to do both things in one step. That is, generate the report, attach it to the email and send it to the given address. I am just not sure how to treat a tempfile() when referencing the file.
I also currently have the app deployed on Shinyapps.io, so saving to file and then retrieving won't work.
Any ideas?

Answer 1

This is the code you need. I tested this and it worked, although my gmail did give me huge bright yellow warnings that the email contains an unverified file that may be dangerous. I also simplified the app a bit and removed some unnecessary code.
library(shiny)
ui <- fluidPage(
sliderInput("slider", "Slider", 1, 100, 50),
actionButton("mail", "send email")
)
sendEmail <- function(email = "RECIPIENT#gmail.com",
mail_message = "Hello",
file = NULL) {
url <- "https://api.mailgun.net/v3/sandboxxxxxxxxxxxxxxxxxxxxxxxx.mailgun.org/messages"
## username:password so api_key is all after the api:
api_key <- "XXXXXXXXXXXXXXXXXX-XXXXXXXXX-XXXXX"
the_body <-
list(
from = "Mailgun Sandbox <postmaster#sandboxXXXXXXXXXXXXXXXXXXX.mailgun.org>",
to = email,
subject = "Mailgun from R test",
text = mail_message
)
if (!is.null(file)) {
the_body$attachment = httr::upload_file(file)
}
req <- httr::POST(url,
httr::authenticate("api", api_key),
encode = "multipart",
body = the_body)
httr::stop_for_status(req)
TRUE
}
server <- function(input, output, session) {
observeEvent(input$mail, {
# 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).
file <- rmarkdown::render(tempReport,
output_file = file.path(tempdir(), "report.html"),
params = params,
envir = new.env(parent = globalenv())
)
sendEmail(file = file)
})
}
shinyApp(ui, server)
By the way, there's also an IMmailgun package in case you're interested, but it achieves essentially what you do with this code.