Question

我有一个RMarkdown模板，template.Rmd：

---
title: "Template"
output: tufte_handout
params:
    data: !r data.frame()
---

```{r setup, include=FALSE}
library(ggplot2)
knitr::opts_chunk$set(echo = TRUE)
```

# Title

## Another Title

```{r echo=FALSE}
ggplot(data = params$data, mapping = aes(x=params$data$X, y=params$data$Y)) +
  geom_point()
```

然后我有了这个R Shiny应用程序，app.R：

library(shiny)
library(rmarkdown)

data <- data.frame(X = 1:10, Y = 11:20)

ui <- fluidPage(fluidRow(column(
  width = 6,
  actionButton("actionButton", "PDF"),
  downloadButton("downloadButton", "PDF")
)))

server <- function(input, output) {
  observeEvent(input$actionButton, {
    renderedFile <- render(
      input = "template.Rmd",
      output_format = "tufte::tufte_handout",
      params = list(data = data),
      output_file = "output.pdf"
    )
    browseURL(renderedFile)


  })
  output$downloadButton <-
    downloadHandler(filename <- "output.pdf",
                    content <-
                      function(file) {
                        renderedFile <- render(
                          input = "template.Rmd",
                          output_format = "tufte::tufte_handout",
                          params = list(data = data),
                          output_file = "output.pdf"
                        )
                        file.copy(renderedFile, file)
                      })
}

shinyApp(ui = ui, server = server)

有一个actionButton和一个downloadButton。它们都应该或多或少地做同样的事情：渲染PDF（准确地说是Tufte讲义），并分别打开下载它。虽然browseURL在我的计算机上运行示例时效果很好，但在＆＃34;真实＆＃34;中运行应用程序时我需要downloadHandler。服务器

actionButton效果很好，但downloadButton失败了：

"C:/PROGRA~2/Pandoc/pandoc" +RTS -K512m -RTS template.utf8.md --to latex --from markdown+autolink_bare_uris+ascii_identifiers+tex_math_single_backslash --output pandoc7146d9cfc5.pdf --template "C:\Users\paedubucher\Documents\R\win-library\3.4\tufte\rmarkdown\templates\tufte_handout\resources\tufte-handout.tex" --highlight-style pygments --latex-engine pdflatex --variable "documentclass:tufte-handout" 
! Undefined control sequence.
<argument> C:\temp 
                   \RtmpAtAlbM \file 714614f62c3_files
l.78 ...62c3_files/figure-latex/unnamed-chunk-1-1}

pandoc.exe: Error producing PDF
Warning: running command '"C:/PROGRA~2/Pandoc/pandoc" +RTS -K512m -RTS template.utf8.md --to latex --from markdown+autolink_bare_uris+ascii_identifiers+tex_math_single_backslash --output pandoc7146d9cfc5.pdf --template "C:\Users\paedubucher\Documents\R\win-library\3.4\tufte\rmarkdown\templates\tufte_handout\resources\tufte-handout.tex" --highlight-style pygments --latex-engine pdflatex --variable "documentclass:tufte-handout"' had status 43
Warning: Error in : pandoc document conversion failed with error 43
Stack trace (innermost first):
    53: pandoc_convert
    52: convert
    51: render
    50: download$func [C:\Users\paedubucher\Documents\R\pdf-download/app.R#28]
     1: runApp
Error : pandoc document conversion failed with error 43

编辑：现在有正确的错误消息。 Pandoc失败（错误43），但在actionButton上下文中运行时一切正常。

Answer 1

GitHub上友好的R Shiny人pointed out the problem。 output_file不应该以这种方式使用。它只是中间的LaTeX文件。 PDF文件的位置从render返回。只需将此文件移动到file参数指向的位置：

  output$downloadButton <-
    downloadHandler(
      filename = "output.pdf",
      content =
        function(file) {
          output <- render(
            input = "template.Rmd",
            output_format = "tufte::tufte_handout",
            params = list(data = data)
          )
          file.copy(output, file)
        }
    )

R Shiny / R Markdown：render（）在downloadHandler中失败

1 个答案: