通过闪亮编织文档的进度条

Question

我试图在我闪亮的 downloadHandler() 周围放置一个进度条。进度条应该显示 rmarkdown HTML 的渲染状态

我在 GitHub (https://github.com/rstudio/shiny/issues/1660) 上找到了此信息，但无法使其正常工作。如果我没有定义环境，则无法编织文件。

app.R

library(shiny)
library(rmarkdown)

ui <-  fluidPage(
  sliderInput("slider", "Slider", 1, 100, 50),
  downloadButton("report", "Generate report"),
  textOutput("checkrender")
)
server <-  function(input, output, session) {
  output$checkrender <- renderText({
     if (identical(rmarkdown::metadata$runtime, "shiny")) {
       TRUE
     } else {
       FALSE
     }
  })

  output$report <- downloadHandler(
    filename = "report.html",
    content = function(file) {

      tempReport <- file.path(tempdir(), "report.Rmd")
      file.copy("report.Rmd", tempReport, overwrite = TRUE)

      params <- list(n = input$slider)

      rmarkdown::render(tempReport, 
                        output_file = file,
                        params = params,
                        envir = new.env(parent = globalenv())
      )
    }
  )
}

shinyApp(ui = ui, server = server)

report.Rmd

---
title: "Dynamic report"
output: html_document
params:
  n: NA
---

```{r}
params$n
```

A plot of `params$n` random points.

```{r}
 plot(rnorm(params$n), rnorm(params$n))
```

Answer 1

您的解决方案非常接近！

我看到你的代码有两个问题：

• 您在 downloadHandler 代码中遗漏了 withProgress 调用
• 测试您是否在闪亮的环境中运行，if (identical(rmarkdown::metadata$runtime, "shiny"))，需要进入您的 .Rmd 文件。您在此测试中包含任何增加/设置进度条的调用，否则 .Rmd 代码将产生类似 Error in shiny::setProgress(0.5) : 'session' is not a ShinySession object. 的错误

下面的代码修改应该可以工作：

app.R

library(shiny)
library(rmarkdown)

ui <-  fluidPage(
  sliderInput("slider", "Slider", 1, 100, 50),
  downloadButton("report", "Generate report"),
  textOutput("checkrender")
)
server <-  function(input, output, session) {
  output$checkrender <- renderText({
    if (identical(rmarkdown::metadata$runtime, "shiny")) {
      TRUE
    } else {
      FALSE
    }
  })

  output$report <- downloadHandler(
    filename = "report.html",
    content = function(file) {
      withProgress(message = 'Rendering, please wait!', {
        tempReport <- file.path(tempdir(), "report.Rmd")
        file.copy("report.Rmd", tempReport, overwrite = TRUE)

        params <- list(n = input$slider)

        rmarkdown::render(
          tempReport,
          output_file = file,
          params = params,
          envir = new.env(parent = globalenv())
        )
      })
    }
  )
}

shinyApp(ui = ui, server = server)

report.Rmd

---
title: "Dynamic report"
output: html_document
params:
  n: NA
---

```{r}
params$n

if (identical(rmarkdown::metadata$runtime, "shiny"))
  shiny::setProgress(0.5)  # set progress to 50%
```

A plot of `params$n` random points.

```{r}
plot(rnorm(params$n), rnorm(params$n))

if (identical(rmarkdown::metadata$runtime, "shiny"))
  shiny::setProgress(1)  # set progress to 100%
```

Answer 2

另一个版本的答案。

对于rmarkdown 1.14 版，jsavn 的回答似乎不起作用。因为 rmarkdown::metadata 没有 $runtime。 （我试图在rmarkdown::render 渲染期间将rmarkdown::metadata$runtime 的值保存为.rds，但它只有YAML 的值，而metadata$runtime 的值是NULL。

因此，为了允许setProgress 使用“非闪亮”渲染，从闪亮应用传递参数可能是更好的解决方案，因为这将不依赖于元数据的值（可能会随着 rmarkdown 版本的变化而变化）。

app.R

library(shiny)
library(rmarkdown)

ui <-  fluidPage(
  sliderInput("slider", "Slider", 1, 100, 50),
  downloadButton("report", "Generate report")
)
server <-  function(input, output, session) {

  output$report <- downloadHandler(
    filename = "report.html",
    content = function(file) {
      withProgress(message = 'Rendering, please wait!', {
        tempReport <- file.path(tempdir(), "report.Rmd")
        file.copy("report.Rmd", tempReport, overwrite = TRUE)

        params <- list(n = input$slider,
                       rendered_by_shiny = TRUE)

        rmarkdown::render(
          tempReport,
          output_file = file,
          params = params,
          envir = new.env(parent = globalenv())
        )
      })
    }
  )
}

shinyApp(ui = ui, server = server)

report.Rmd

---
title: "Dynamic report"
output: html_document
params:
  n: 10
  rendered_by_shiny: FALSE
---

```{r}
params$n

if (params$rendered_by_shiny)
  shiny::setProgress(0.5)  # set progress to 50%
```

A plot of `params$n` random points.

```{r}
plot(rnorm(params$n), rnorm(params$n))

if (params$rendered_by_shiny)
  shiny::setProgress(1)  # set progress to 100%
```