Saving time on clicking action button in shiny - shiny

Question

I have created a shiny app to save start time and and end time when I click these buttons. I have three buttons: Start, End and Download, this app is intended to save the time when I have clicked Start and End buttons and then save the file in .csv when I click Download button. But it is saving the time of Download button click. Please help me save the different time properly.
library(shiny)
shinyUI(fluidPage(
titlePanel("Header"),
sidebarLayout(
sidebarPanel(
actionButton("start", "Start"),
tags$br(),
actionButton("end", "End"),
tags$br(),
downloadButton("downloadData", "Download")
),
mainPanel(
)
)
))
shinyServer(function(input, output) {
startTime <- eventReactive(input$start,{
Sys.time()
})
endTime <- eventReactive(input$end,{
Sys.time()
})
data <- reactive({data.frame(start = startTime(),
end = endTime())})
output$downloadData <- downloadHandler(
filename = function() {
"download.csv"
},
content = function(file) {
write.csv(data(), file, row.names = F)
}
)
})

Answer 1

Use global variables would work. Example below (edited to use per-session global variable).
library(shiny)
ui <- shinyUI(fluidPage(
titlePanel("Header"),
sidebarLayout(
sidebarPanel(
actionButton("start", "Start"),
tags$br(),
actionButton("end", "End"),
tags$br(),
downloadButton("downloadData", "Download")
),
mainPanel(
)
)
))
server <- shinyServer(function(input, output) {
starttime <- NULL
endtime <- NULL
observeEvent(input$start, {
starttime <<- Sys.time()
})
observeEvent(input$end, {
endtime <<- Sys.time()
})
output$downloadData <- downloadHandler(
filename = function() {
"download.csv"
},
content = function(file) {
data <- data.frame(start=starttime, end=endtime)
write.csv(data, file, row.names = F)
}
)
})
shinyApp(ui = ui, server = server)