Shiny modal dialog in response to multiple buttons - r

Question

Consider the following app:
ui <- basicPage(
actionButton('button1', 'click one'),
actionButton('button2', 'click two')
)
server <- function(input, output){
popup <- function(){
modalDialog(easyClose = T,
'popup window triggered')
}
}
shinyApp(ui=ui, server=server)
My goal is that the modal window is triggered once either of the buttons is clicked. I realise that I can create an observeEvent for each button, but in the full application there will be many buttons on different navbar pages. So in order to avoid a whole bunch of code duplication, I would like to gather them in a single observeEvent. I tried some of the suggestions from here.
Adding
observeEvent({
input$button1
input$button2
}, {
showModal(popup())
})
to server() doesn't really work, because for some odd reason button2 needs to be clicked before button1 is responsive.
Instead, adding
observeEvent(c(input$button1, input$button2), {
showModal(popup())
})
causes the modal window to appear on startup already, which should not happen.
So is there a way to capture multiple action buttons into a single observe event without these undesirable behaviours?

Answer 1

You need to set ignoreInit = TRUE for observeEvent:
ui <- basicPage(
actionButton('button1', 'click one'),
actionButton('button2', 'click two')
)
server <- function(input, output){
popup <- function(){
modalDialog(easyClose = T,
'popup window triggered')
}
observeEvent(c(input$button1, input$button2), {
showModal(popup())
}, ignoreInit = TRUE)
}
shinyApp(ui=ui, server=server)