R shiny: display "loading..." message while function is running
I use Shiny GUI R package. I'm looking for a way to display a message like "loading..." after the actionButton was pressed. The function takes several minutes to execute, so I need to inform the user somehow that the button actually triggered some event. Now the server.R code looks like this:
DATA <- reactive({
if(input$DownloadButton>0) {
RunDownload()
} else {
NULL
}
})
output$Download <- renderText({
if(NROW(DATA())>0) {
paste0(Sys.time(),": ",NROW(DATA()), " items downloaded")
} else {
''
}
})
actionButton()
is a function that downloads data from internet. input$DownloadButton
is actionButton. So after the button was pressed the user waits for several minutes and only then sees a message saying that download was successful. I would like to show a message "Loading..." just after the actionButton was pressed and then another message like paste0(Sys.time(),": ",NROW(DATA()), " items downloaded")
when execution ends.
I'm already using a simpler and more reliable way than the one I posted before.
A combination of
tags$style(type="text/css", "
#loadmessage {
position: fixed;
top: 0px;
left: 0px;
width: 100%;
padding: 5px 0px 5px 0px;
text-align: center;
font-weight: bold;
font-size: 100%;
color: #000000;
background-color: #CCFF66;
z-index: 105;
}
")
with
conditionalPanel(condition="$('html').hasClass('shiny-busy')",
tags$div("Loading...",id="loadmessage")
)
Example:
runApp(list(
ui = pageWithSidebar(
headerPanel("Test"),
sidebarPanel(
tags$head(tags$style(type="text/css", "
#loadmessage {
position: fixed;
top: 0px;
left: 0px;
width: 100%;
padding: 5px 0px 5px 0px;
text-align: center;
font-weight: bold;
font-size: 100%;
color: #000000;
background-color: #CCFF66;
z-index: 105;
}
")),
numericInput('n', 'Number of obs', 100),
conditionalPanel(condition="$('html').hasClass('shiny-busy')",
tags$div("Loading...",id="loadmessage"))
),
mainPanel(plotOutput('plot'))
),
server = function(input, output) {
output$plot <- renderPlot({ Sys.sleep(2); hist(runif(input$n)) })
}
))
tags$head() is not required, but it's a good practice to keep all the styles inside head tag.
Very simply, you can use built-in shiny functions showModal()
at the start of the function and removeModal()
at the end. If you remove the footer, said modal cannot be clicked out of.
Example:
observeEvent(input$button, {
showModal(modalDialog("Doing a function", footer=NULL))
#Do the stuff here....
#...
#...
#Finish the function
removeModal()
})