The download_link() provides a standard way to provide a download link,
which facilitates important accessible / positive user experience elements,
namely:
file type
file size
These are necessary in order for users to understand what they are downloading, both in terms of being able to decide if they are comfortable with downloading the file over their current connection and if it's in a form they're able to deal with once it is downloaded. If the exact file size is not easily determined, then it may be acceptable to provide an estimate or an upper limit.
Arguments
- outputId
The name of the output slot that the
shiny::downloadHandler()is assigned to.- link_text
Text that will appear describing the download action. Vague text like 'click here' or 'here' will cause an error, as will ending in a full stop. Leading and trailing white space will be automatically trimmed. If the string is shorter than 7 characters a console warning will be thrown. There is no way to hush this other than providing more detail.
- file_type
The file type to be download (default: CSV)
- file_size
The file size if known. Needs to be a string ending in one of KB, MB, GB or rows.
Examples
if (interactive()) {
ui <- shiny::fluidPage(
gov_text("Choose a data set to download."),
select_Input(
"dataset",
"Data set",
select_text = c("Car road tests", "New York air quality"),
select_value = c("mtcars", "airquality")
),
gov_text(
download_link(
"download_data",
"Download selected data set",
file_size = "4 KB"
)
)
)
server <- function(input, output) {
# The requested data set
data <- reactive({
get(input$dataset)
})
output$download_data <- downloadHandler(
filename = function() {
# Use the selected dataset as the suggested file name
paste0(input$dataset, ".csv")
},
content = function(file) {
# Write the dataset to the `file` that will be downloaded
write.csv(data(), file)
}
)
}
shiny::shinyApp(ui, server)
}