Archive button in R shiny, activate only once - r

Question

I have the following code which runs perfectly!. However, I want to restrict the archiving of the data by pushing the "Export All" button to only once per day. I tried to use if statements and not successful. Another fact is the code is running over Shiny-Server pro and different browser sessions will be created. Any Suggestions?.
library(shiny)
library(shinyBS)
library(XLConnect)
library(lubridate)
cData <- '
Candidate,Party,Province,Age,Gender
"L, L",NDP,Quebec,22,Female
"M, M",Bloc Quebecois,Quebec,43,Female
"M, S",Bloc Quebecois,Quebec,34,Female
"S, D",NDP,Quebec,,Female
"S, L",NDP,Quebec,72,Female
"F, H",Liberal,British Columbia,71,Female
"T, N",NDP,Quebec,70,Female
"S, J",Liberal,Ontario,68,Female
"R, Francine",NDP,Quebec,67,Female
"D, Patricia",Conservative,Ontario,66,Female
"S, Joy",Conservative,Manitoba,65,Female
"W, Alice",Conservative,British Columbia,64,Female
"O, Tilly",Conservative,New Brunswick,63,Female
"A, Diane",Conservative,Alberta,63,Female
"D, Linda",NDP,Alberta,63,Female
"B, Carolyn",Liberal,Ontario,62,Female
"N, Peggy",NDP,Ontario,61,Female
"M, Irene",NDP,Ontario,61,Female
"S, Jinny",NDP,British Columbia,60,Female
"F, Judy",Liberal,Newfoundland,60,Female
"C, Jean",NDP,British Columbia,60,Female
"D, Libby",NDP,British Columbia,59,Female
"Y, Lynne",Conservative,Saskatchewan,59,Female
"D, Anne",NDP,Quebec,58,Female
"M, Elizabeth",Green,British Columbia,58,Female
"M, Joyce",Liberal,British Columbia,58,Female
"F, Kerry",Conservative,British Columbia,57,Female
"B, Lois",Conservative,Ontario,57,Female
"B, Marj",NDP,Quebec,57,Female
"C, Joan",Conservative,Alberta,56,Female
"C, Olivia",NDP,Ontario,55,Female
"M, Cathy",Conservative,British Columbia,55,Female
"F, Diane",Conservative,Ontario,55,Female
"L, Helene",NDP,Quebec,54,Female
"G, Nina",Conservative,British Columbia,54,Female
"H, Carol",NDP,Ontario,54,Female
"P, Gail",Conservative,Prince Edward Island,53,Female
"T, Susan",Conservative,Ontario,53,Female
"Y, Wai",Conservative,British Columbia,52,Female'
con <- textConnection(cData)
cEl <- read.csv(con, header=TRUE, stringsAsFactors = FALSE)
cEl$votes <- round(runif(nrow(cEl), min=500, max=15000))
TheDataDF <- cEl
ui <- fluidPage(
titlePanel("Archive Data Post on Stack Overflow"),
# Button and Alert, we use the alert to control only onetime Archive
sidebarLayout(
sidebarPanel(
bsAlert("alert"),
downloadButton("ArchiveBtn", "Archive All")
),
# Show the table
mainPanel(
DT::dataTableOutput('TheData')
)
)
)
server <- function(input, output,session) {
output$TheData <- DT::renderDataTable(DT::datatable(TheDataDF,options = list(pageLength = 25,scrollX = TRUE),
rownames = FALSE,class = 'cell-border stripe')
%>% formatStyle(c(2:ncol(TheDataDF)),
color = styleInterval(55, c('red', 'black'))))
output$ArchiveBtn <- downloadHandler(
filename = function() {
paste("ArchiveData-", ymd(Sys.Date()), ".xlsx", sep="")
},
content = function(file) {
fname <- paste(file,"xlsx",sep=".")
wb <- loadWorkbook(fname, create = TRUE)
#creating sheets within the Excel workbook
createSheet(wb, name = "The Arc Data")
#writing into sheet within the Excel workbook :
writeWorksheet(wb, TheDataDF, sheet = "The Arc Data", startRow = 1, startCol = 1)
saveWorkbook(wb)
file.rename(fname,file)
# Create the message for the complition of the archive
createAlert(session, "alert", "exampleAlert", style="success",title = "Archive Complete!",
content = "Data archived", append = FALSE)
}
)
}
# Run the application
shinyApp(ui = ui, server = server)