闪亮报告：试图将输入值作为参数传递给编织.RMD文档，但失败

Question

这个简单的闪亮应用程序具有各种可选选项（selectInput）的下拉列表，SelectInput中的每个选项都有一个.rmd文件匹配其名称。基于通过下拉列表选择的选项，我试图调用其各自的.RMD文件，在下面完成代码。

EventReactive（）方法似乎获得了选定的值，并将其作为输入传递，以调用相应的.RMD文件，但是代码执行但没有生成报告。

另外，请评论EventReactive（）并将所需的.RMD文件作为变量（report_name）生成带有所需内容的可下载报告。我该如何解决此问题以获得所需的功能？

app.r

library(shiny)

ui <- fluidPage(
  selectInput("select_id",
              "Select an option",
              list(
                " "=" ",
                "apples"='apples',
                "oranges"='oranges')
  ),
  radioButtons('format', 'Document format', c('HTML', 'Word'),
               inline = TRUE),
  
  downloadButton('downloadReport')
)

server <- function(input, output, session) {
  
  # download of report selectable format based on button press
  output$downloadReport <- downloadHandler(
    filename = function() {
      paste('my-report', sep = '.', switch(
        input$format, PDF = 'pdf', HTML = 'html'
      ))
    },
    
    # get selected option from dropdown and use the input value as the name to call the Rmd file
    report_name <- eventReactive(input$select_id, {
      paste(input$select_id,'Rmd', sep =".")
    }),

    # replacing report_name() with report_name [below line] generates report, but is not the desired outcome
    # report_name <- "apples.Rmd",
    
    content = function(file) { 
      cat('The selected fruit report is - - - :',report_name())
      
      src <- normalizePath(report_name())
      # temporarily switch to the temp dir, in case you do not have write
      # permission to the current working directory
      owd <- setwd(tempdir())
      on.exit(setwd(owd))
      file.copy(src, report_name(), overwrite = TRUE)
      
      out <- rmarkdown::render(report_name(),
                               switch(input$format,
                                      PDF = pdf_document(),
                                      HTML = html_document()
                               ))
      file.rename(out, file)
    } 
  ) 
}

shinyApp(ui, server)

apples.rmd

---
title: "This is a report for Apples"
output: html_document
params:
  tbl: NA
  include: NA
---

oranges.rmd

---
title: "This is a report for Oranges"
output: html_document
params:
  tbl: NA
  include: NA
---

Answer 1

要纠正的几件事：

• report_name＆lt; - ...应在下载handler之外。
• 如果输入$ select_id是“” 选择，则可能应该不是 允许下载。为此，我们req uire是其他的。
• 渲染但不是pdf_document等。

server <- function(input, output, session) {
  # get selected option from dropdown and use the input value as the name to call the Rmd file
  report_name <- eventReactive(input$select_id, {                       # MOVED
    req(input$select_id != " ")                                         # ADDED
    paste(input$select_id,'Rmd', sep =".")
  })

  # download of report selectable format based on button press
  output$downloadReport <- downloadHandler(
    filename = function() {
      paste('my-report', sep = '.', switch(
        input$format, PDF = 'pdf', HTML = 'html'
      ))
    },
    content = function(file) {
      req(nzchar(report_name()))                                        # ADDED
      cat('The selected fruit report is - - - :',report_name())

      src <- normalizePath(report_name())
      # temporarily switch to the temp dir, in case you do not have write
      # permission to the current working directory
      owd <- setwd(tempdir())
      on.exit(setwd(owd))
      file.copy(src, report_name(), overwrite = TRUE)

      out <- rmarkdown::render(report_name(),
                               switch(input$format,
                                      PDF = rmarkdown::pdf_document(),  # CHANGED
                                      HTML = rmarkdown::html_document() # CHANGED
                               ))
      file.rename(out, file)
    }
  )
}

（

• 次要）您:: -Reference 在尝试渲染报告名称之前的存在，以抢占与路径相关的问题，如果用户可能看不到相关的错误消息。 （是否不是，取决于您正确处理路径的自信心。）

• 您的模板包括参数：，但您没有在Render（。）。我假设此处省略了它，但请确保您将params = ...添加到渲染调用中。

  


• 您的输入$ select_id优惠<代码>“ html” 和“ word”，但是您的switch> switch语句正在寻找PDF和html。当选择HTML时，上述有效，但是您需要更新selectInput和switch> switch语句以确保正确引用所有候选人。