How to customize downloadHandler-button in Rmarkdown document-CodePudding

In shiny a downloadHandler is combined with an actionButton/downloadButton in the UI-Part. Thus you easily can change the buttons label by typing:

downloadButton("btn_export", "Export")

Here is a little shinyapp with just one button to export some example data:

library(shiny)

ui <- fluidPage(
    downloadButton("btn_export", "Export")
)

server <- function(input, output) {
    data <- mtcars
    
    output$btn_export <- downloadHandler(
        filename = function() {
            paste0("shiny_", Sys.Date(), ".csv")
        },
        content = function(file) {
            write.csv(data, file)
        }
    )
}

shinyApp(ui, server)

In Rmarkdown the downloadHandler is added directly to a code chunk:

```{r, echo=FALSE}
downloadHandler(
  filename = function() {
    paste0("rmd_", Sys.Date(), ".csv")
  },
  content = function(file) {
    write.csv(data, file)
  }
)
```

How can I change the label of the download button?

A complete example:

---
title: "test"
runtime: shiny
output: html_document
---

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

```{r data_prep, include=FALSE}
data <- mtcars
```

```{r download, echo=FALSE}
downloadHandler(
  filename = function() {
    paste0("rmd_", Sys.Date(), ".csv")
  },
  content = function(file) {
    write.csv(data, file)
  }
)
```

Edit:

The upper reproducible minimal example might be too minimal. The downloadHandler in my real Rmarkdown document is rendering a static Rmd-report for download:

downloadHandler(filename = function() {
    return("CaRe.html")
  }, content = function(file) {
     rmarkdown::render(input = "CaRe_static.Rmd", 
                       output_file = file,
                       params = list(in_rohdaten = input$in_rohdaten$datapath,
                                     in_kunde = input$in_kunde,
                                     in_kampagne = input$in_kampagne,
                                     in_auftrag = input$in_auftrag,
                                     in_datum = input$in_datum
     ))
  }, contentType = "text/html"
)

Just in case that is relevant for the solution.

CodePudding user response：

Not sure how to do it using downloadHandler() but you can try downloadthis package.

---
title: "test"
runtime: shiny
output: html_document
---

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

```{r, include=FALSE}
library(downloadthis)

data <- mtcars
```

```{r, echo=FALSE}
download_this(mtcars,
  output_name = "mtcars data set",
  output_extension = ".csv",
  button_label = "Download mtcars",
  button_type = "warning",
  has_icon = TRUE,
  icon = "fa fa-save"
)

CodePudding user response：

Argh, it's so simple if you carefully read the manual. Sorry for wasting your time.

You can use the outputArgs parameter of downloadHandler to change the label of the download-button:

---
title: "test"
runtime: shiny
output: html_document
---

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

```{r data_prep, include=FALSE}
data <- mtcars
```

```{r download, echo=FALSE}
downloadHandler(
  filename = function() {
    paste0("rmd_", Sys.Date(), ".csv")
  },
  content = function(file) {
    write.csv(data, file)
  },
  outputArgs = list(label = "Export")  # <--- That's it!
)
```