在R Shiny中实现将编织临时文件附加至邮件的功能

Got it, let's get this working smoothly for you! The core idea is to first generate your RMarkdown report to a temporary file when the email button is clicked, then include that file as an attachment in your Mailgun API request. Here's the complete implementation:

Step 1: Required Packages #

First, make sure these packages are installed and loaded—they handle Shiny interactions, report rendering, API calls, and MIME type detection:

install.packages(c("shiny", "rmarkdown", "httr", "mime"))

Step 2: UI Code (No Major Changes) #

Your existing UI works perfectly; I’ve included it here for completeness:

library(shiny)

shinyUI(fluidPage(
  sliderInput("slider", "Slider", 1, 100, 50),
  downloadButton("report", "Generate report"),
  actionButton("mail", "Send Email"),
  textOutput('mailStatus')
))

Step 3: Full Server Logic with Attachment Support #

Here’s the updated server.R code that ties report generation and email sending together. Replace the placeholder values (like YOUR_MAILGUN_API_KEY) with your actual Mailgun credentials:

library(shiny)
library(rmarkdown)
library(httr)
library(mime)

shinyServer(function(input, output) {
  
  # Reusable function to generate the report (works for both download and email)
  generate_report <- function() {
    # Create a unique temporary file to hold the report (use .html for HTML reports)
    temp_report <- tempfile(fileext = ".pdf")
    
    # Render the RMarkdown report, passing the slider value as a parameter
    render("report.Rmd", 
           output_file = temp_report,
           params = list(slider_value = input$slider))
    
    return(temp_report)
  }
  
  # Existing download handler for standalone report downloads
  output$report <- downloadHandler(
    filename = function() {
      paste0("report_", Sys.Date(), ".pdf")
    },
    content = function(file) {
      file.copy(generate_report(), file)
    }
  )
  
  # Email sending logic with attachment
  observeEvent(input$mail, {
    # Generate the report first
    report_path <- generate_report()
    
    # Mailgun API configuration - replace these with your own details!
    mailgun_api_key <- "YOUR_MAILGUN_API_KEY"
    mailgun_domain <- "YOUR_MAILGUN_DOMAIN" # e.g., "mg.yourdomain.com"
    from_email <- "Your Shiny App <noreply@yourdomain.com>"
    to_email <- "recipient@example.com"
    email_subject <- "Your Requested Report"
    email_body <- "Attached is the report generated from the Shiny app."
    
    # Send POST request to Mailgun API with the attachment
    response <- POST(
      url = paste0("https://api.mailgun.net/v3/", mailgun_domain, "/messages"),
      authenticate("api", mailgun_api_key),
      body = list(
        from = from_email,
        to = to_email,
        subject = email_subject,
        text = email_body,
        attachment = upload_file(report_path, type = mime::guess_type(report_path))
      )
    )
    
    # Update status message for the user
    if (http_status(response)$category == "Success") {
      output$mailStatus <- renderText("Email sent successfully!")
    } else {
      output$mailStatus <- renderText(paste("Failed to send email. Error:", content(response)$message))
    }
    
    # Clean up the temporary file (good practice to avoid clutter)
    file.remove(report_path)
  })
  
})

Key Details to Note: #

• Reusable Report Logic: The generate_report() function is shared between the download button and email button, so you don’t duplicate code.
• Temporary Files: tempfile() creates a unique, isolated file for each report, preventing conflicts and getting cleaned up after sending.
• Mailgun Setup: Ensure your Mailgun domain is verified and your API key has permission to send emails with attachments.
• RMarkdown Params: Your report.Rmd needs a params section to accept the slider value. Here’s a quick example of the top of your .Rmd file:

  ---
  title: "Generated Report"
  params:
    slider_value: NA
  ---
  
  ## Report Details
  Slider value at generation: **`r params$slider_value`**
  

• MIME Type Detection: mime::guess_type() ensures Mailgun correctly identifies the attachment format (PDF, HTML, etc.).

内容的提问来源于stack exchange，提问作者eflores89