Creating a notiftication when function is initiated in a Shiny Application - r

Question

I have the following R Shiny Application:
library(shiny)
shinyApp(
ui = dashboardPage(
dashboardHeader(
title = "Tweetminer",
titleWidth = 350
),
dashboardSidebar(
width = 350,
sidebarMenu(
menuItem("Menu Item")
)
),
dashboardBody(
fluidRow(
tabBox(
tabPanel("Select tweets",
numericInput("tweet_amount", "Amount of tweets:", 10, min = 1, max = 100),
div(style="display:inline-block",numericInput("tweet_long", "Longitude:", 10, min = 1, max = 100)),
div(style="display:inline-block",numericInput("tweet_lat", "Latitude:", 10, min = 1, max = 100)),
#selectInput("tweet_name", "Account name", choices = c("#realDonaldTrump","#GorgeNails"), width = NULL, placeholder = NULL),
selectInput("tweet_name", "Account name", choices = c("#realDonaldTrump","#Yankees"), selected = NULL, multiple = FALSE,
selectize = TRUE, width = NULL, size = NULL),
actionButton("get_tweets", "Fetch the tweets"),
hidden(
div(id='text_div',
verbatimTextOutput("text")
)
)
)
)
)
)
),
server = function(input, output) {
test_list <- c(1,2,3)
run_function <- reactive({
for(i in test_list){
Sys.sleep(2)
}
})
observeEvent(input$get_tweets, {
run_function()
toggle('text_div')
output$text <- renderText({"You're now connecting to the API"})
})
}
)
This application should allow users to input parameters after which tweets will be scraped. However - because it will take some time Im looking for a way to inform users this will take a while.
Using this function:
observeEvent(input$get_tweets, {
run_function()
toggle('text_div')
output$text <- renderText({"You're now connecting to the API"})
})
I inform the user that the function (run_function() in this example, a mockup but just for reproducing purposes) is ready. However Im looking for a notice after you initiate the function and when its done.
So after you press the first time it should say something like - function initiated and after the function is ready -> "You .. api".
Any thoughts on what I should change to get this working?

Answer 1

You can use withProgress function, check this example:
output$plot <- renderPlot({
withProgress(message = 'Calculation in progress', detail = 'This may take a while...', value = 0, {
for (i in 1:15) {
incProgress(1/15)
Sys.sleep(0.25)
}
})
plot(cars)
})
More info
EDIT: New example:
library(shiny)
ui <- fluidPage(
actionButton(inputId = 'DoSomething', label = 'Do something'),
verbatimTextOutput('t1')
)
server <- function(input, output, session) {
output$t1 <- renderPrint('Doing nothing...')
run_function <- reactive({
withProgress(message = "Starting...", max = 60, value = 0, {
for (i in 1:25) {
incProgress(1)
Sys.sleep(0.25)
}
setProgress(message = "Connected..")
for (i in 1:25) {
incProgress(1)
Sys.sleep(0.25)
}
setProgress(message = "Doing Stuffs...")
for (i in 1:10) {
incProgress(1)
Sys.sleep(0.25)
}
setProgress(message = "Disconecting...")
})
return('Finish')
})
observeEvent(input$DoSomething, {
output$t1 <- renderPrint(run_function())
})
}
shinyApp(ui, server)