Download file from server to local directory using Shiny - r

Question

I am not sure if I am understanding this correctly. Where should the data set that I want to download be in RStudio server? I do not want to deploy yet, so I am not using the Shiny server, but I want to use the download functionality and save the data set as a file in a local directory.
I have uploaded a file using Shiny fileInput and I have saved the file using copy.file(). I was told that the uploaded file is saved to the server. The file is called 0.tsv. Afterwards, I read that file and download it. The GUI works, but the file doe not get written to a file and saved to the local directory. My question is: is there any thing missing in my approach?
library(shiny)
ui <- fluidPage(
titlePanel('File download'),
sidebarLayout(
sidebarPanel(
selectInput("dataset", "Choose a dataset:",
choices = c("data")),
radioButtons("filetype", "File type:",
choices = c( "tsv")),
downloadButton('downloadData', 'Download')
),
mainPanel(
tableOutput('table')
)
)
)
function(input, output) {
datasetInput <- reactive({
# Fetch the appropriate data object, depending on the value
# of input$dataset.
data <- read.table("home/user/0.tsv")
switch(input$dataset,
"data" = data)
})
output$table <- renderTable({
datasetInput()
})
# downloadHandler() takes two arguments, both functions.
# The content function is passed a filename as an argument, and
# it should write out data to that filename.
output$downloadData <- downloadHandler(
# This function returns a string which tells the client
# browser what name to use when saving the file.
filename = function() {
paste(input$dataset, input$filetype, sep = ".")
},
# This function should write data to a file given to it by
# the argument 'file'.
content = function(file) {
sep <- switch(input$filetype, "tsv" = "\t")
# Write to a file specified by the 'file' argument
write.table(datasetInput(), file, sep = sep,
row.names = FALSE)
}
)
}
shinyApp(ui = ui, server = server)
ui <- fluidPage(
titlePanel('File download'),
sidebarLayout(
sidebarPanel(
selectInput("dataset", "Choose a dataset:",
choices = c("data")),
radioButtons("filetype", "File type:",
choices = c( "tsv")),
downloadButton('downloadData', 'Download')
),
mainPanel(
tableOutput('table')
)
)
)
function(input, output) {
datasetInput <- reactive({
# Fetch the appropriate data object, depending on the value
# of input$dataset.
data <- read.table("home/user/0.tsv")
switch(input$dataset,
"data" = data)
})
output$table <- renderTable({
datasetInput()
})
# downloadHandler() takes two arguments, both functions.
# The content function is passed a filename as an argument, and
# it should write out data to that filename.
output$downloadData <- downloadHandler(
# This function returns a string which tells the client
# browser what name to use when saving the file.
filename = function() {
paste(input$dataset, input$filetype, sep = ".")
},
# This function should write data to a file given to it by
# the argument 'file'.
content = function(file) {
sep <- switch(input$filetype, "tsv" = "\t")
# Write to a file specified by the 'file' argument
write.table(datasetInput(), file, sep = sep,
row.names = FALSE)
}
)
}
shinyApp(ui = ui, server = server)

Answer 1

Thanks very much for your response. Below is the correct way to do it. This works fine.
server <- function(input, output) {
# Reactive value for selected dataset ----
datasetInput <- reactive({
switch(input$dataset,
"params" = params)
})
# Table of selected dataset ----
output$table <- renderTable({
datasetInput()
})
# Downloadable csv of selected dataset ----
output$downloadData <- downloadHandler(
filename = function() {
paste(input$dataset, ".csv", sep = "")
},
content = function(file) {
write.table(datasetInput(), file, row.names = FALSE)
}
)
}