我正在按照https://github.com/RLesur/chrome_print_shiny的示例构建一个Shiny应用程序，它将从.Rmd文件生成.pdf输出。我可以让示例应用程序.R在本地运行（对于大多数选择），但修改最终将使用render(params())的.Rmd并不成功。

ReportGenerator.Rmd

---
title: "Test Report"
output:
  pagedown::html_paged:
    includes:
    number_sections: false
    self_contained: true
    css:
       - default

params:
  gonna: "a"
  have: "b"
  some: "c"
  later: "d"
#knit: pagedown::chrome_print # commented out for use in Shiny
---

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

Summary

summary(cars)

Plot

plot(pressure)

字符串

**app.R**

library(pagedown)
library(promises)
library(rmarkdown)
library(shiny)
library(shinybusy)

chrome_extra_args <- function(default_args = c("--disable-gpu")) {
args <- default_args

Test whether we are in a shinyapps container

if (identical(Sys.getenv("R_CONFIG_ACTIVE"), "shinyapps")) {
args <- c(args,
"--no-sandbox", # required because we are in a container
"--disable-dev-shm-usage") # in case of low available memory
}
args
}

send the .Rmd to temp

tempReport <- tempfile(fileext=".Rmd")
file.copy("ReportGenerator.Rmd", tempReport, overwrite=TRUE)

ui <- fluidPage(
actionButton( # build the report
inputId="buildBtn",
label="Build Report"
),
uiOutput("downloadBtn") # download the report
)

server <- function(input, output) {
observeEvent(input$buildBtn, {
output$downloadBtn <- renderUI({
show_modal_spinner()
# generate PDF
chrome_print(
render(tempReport,
# will have params here later
envir = new.env(parent = globalenv())
),
output=tempfile(fileext=".pdf"),
extra_args=chrome_extra_args(),
verbose=1,
async=TRUE
)$then(
onFulfilled=function(value){
showNotification("PDF file successfully generated", type="message")
output$downloadBtn <- downloadHandler(
filename="Report.pdf",
content=function(file){
file.copy(value, file) # I think the problem is here?
},
contentType="application/pdf"
)
downloadButton(
outputId="downloadBtn",
label="Download Report"
)
},
onRejected=function(error){
showNotification(
error$message,
duration=NULL,
type="error"
)
HTML("")
}
)$finally(remove_modal_spinner)
})

})

}

shinyApp(ui = ui, server = server)

型
单击“Build Report”按钮确实生成了.pdf文件--使用`tempdir()`，我可以导航到会话的临时目录，看到.Rmd文件已经被绑定，.pdf文件就在那里，用通常的临时文件哈希命名，打开时看起来和预期的一样。然而，单击“Download Report”按钮并不提供. pdf文件。相反，我得到一个.html文件的对话框，它不包括`downloadHandler`中指定的文件名。打开它会产生一个.html窗口，看起来与原始的Shiny应用程序页面相似。
x1c 0d1x的数据
考虑到.pdf * 确实 * 生成了，我猜问题出在`downloadHandler(content)`的某个地方，但是我不太熟悉`chrome_print(async=TRUE)`如何与`library(promises)`、`$then()`和临时文件一起工作，以便将.pdf从Temp目录中拉出并将其插入处理程序。