Save DT table with additional information (Shiny) - shiny

Question

I was wondering if it is possible to save DT table content together with some additional information which is not part of the data frame/table like app version number, date of execution, sliderInput value etc.
Thank you!
Reprex below:
library(shiny)
library(DT)
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
sliderInput(inputId = "range", "Set range", 1, 10, 5, 1)
),
mainPanel(
DT::dataTableOutput("table")
)
)
)
server <- function(input, output) {
dfr <- data.frame(var1 <- c(1,2,3),
var2 <- c(11, 22, 33))
output$table <- DT::renderDataTable(
datatable(dfr, extensions = 'Buttons',
class="cell-border stripe",
rownames = FALSE, colnames = c("var1", "var2"),
options = list(dom = "Blfrtip",
buttond = list("copy", list(extend = "collection",
buttons = c("csv", "excel", "pdf"),
text = "Download")), pageLength=10, autoWidth = TRUE,
searchHighlight = TRUE, filter = "top"))
)
}
shinyApp(ui = ui, server = server)

Answer 1

You could save the contents of the data frame and the other information in a list and then save the list.
Or, any R object can have attributes which are completely arbitrary and under your control. You could set attributes of the data frame to record the information you want.
Personally, I'd use the list approach, purely because I don't like attributes.
Here's a suggestion in response to OP's request below.
library(shiny)
library(DT)
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
sliderInput(inputId = "range", "Set range", 1, 10, 5, 1),
actionButton("saveRds", "Save to Rds"),
actionButton("loadRds", "Load from Rds")
),
mainPanel(
DT::dataTableOutput("table"),
wellPanel(h4("Current data"), verbatimTextOutput("text")),
wellPanel(h4("File data"), verbatimTextOutput("loadedData"))
)
)
)
server <- function(input, output) {
dfr <- data.frame(var1 <- c(1,2,3),
var2 <- c(11, 22, 33))
output$table <- DT::renderDataTable(
datatable(dfr, extensions = 'Buttons',
class="cell-border stripe",
rownames = FALSE, colnames = c("var1", "var2"),
options = list(dom = "Blfrtip",
buttond = list("copy", list(extend = "collection",
buttons = c("csv", "excel", "pdf"),
text = "Download")), pageLength=10, autoWidth = TRUE,
searchHighlight = TRUE, filter = "top"))
)
listInfo <- reactive({
list("data"=dfr, "version"="WebApp Version 1.0", "runDate"=date(), "sliderValue"=input$range)
})
output$text <- renderPrint({
listInfo()
})
observeEvent(input$saveRds, {
saveRDS(listInfo(), "data.Rds")
})
fileData <- reactive({
req(input$loadRds)
readRDS("data.Rds")
})
output$loadedData <- renderPrint({
fileData()
})
}
shinyApp(ui = ui, server = server)
The way you implement "save to file" will depend on the file format: Excel files will clearly have different requirements to PDF files, for example. As a minimum effort demonstation, I've created "Save to Rds" and "Load from RDS" buttons in the sidebar and added a verbatimTextOutput to display the contents of the file when it's loaded. [I'm not sufficiently familiar with DT to know how to add the buttons in the table toolbar.]
OP's effort was pretty close: it's just that writing a list to CSV file takes a little more effort than just calling write.csv...