looping error in alert generation with shinyalert - r

Question

Good days, I am programming in Rstudio, using shiny, and I wanted to generate an alert that is activated only when I want to leave a tabPanel without completing a condition, but not if I do not enter the tabPanel before, this is the way I found. The problem is that every time that I leave the Panel 1 without fulfilling the condition of completing text, alerts are generated that are accumulating (1 alert the first time, two the second, three the third, etc.) I wanted to consult if somebody knows why it is this and how to avoid it.
thank you very much
library(shiny)
library(ggplot2)
library(shinyalert)
ui <- fluidPage(
tabsetPanel(
id = "tabselected",
tabPanel("Tab2",""),
tabPanel("Tab1", textInput("requiredText", "Required Text"))
))
server <- function(input, output, session) {
observe({
req(input$tabselected == "Tab1")
observeEvent(
input$tabselected,
if (input$tabselected != "Tab1" & !isTruthy(input$requiredText)) {
shinyalert(title = "Save your work before changing tab",
type = "warning",
showConfirmButton = TRUE
)
updateTabsetPanel(session, inputId = "tabselected", selected = "Tab1")
}
)
}
)
}
shinyApp(ui = ui, server = server)

Answer 1

Is this the behavior you desire? Your example was recursive so you had reoccurring popup event. We can create a reactiveValues variable to keep track of the events, like so:
library(shiny)
library(ggplot2)
library(shinyalert)
ui <- fluidPage(
tabsetPanel(
id = "tabselected",
tabPanel("Tab2",""),
tabPanel("Tab1", textInput("requiredText", "Required Text"))
))
server <- function(input, output, session) {
v <- reactiveValues(to_alert = FALSE)
observeEvent(input$tabselected,{
if (input$tabselected != "Tab1" & !isTruthy(input$requiredText)) {
v$to_alert <- TRUE
}else{
v$to_alert <- FALSE
}
},ignoreInit = TRUE)
observeEvent(v$to_alert,{
if (v$to_alert){
shinyalert(title = "Save your work before changing tab", type = "warning",showConfirmButton = TRUE)
updateTabsetPanel(session, inputId = "tabselected", selected = "Tab1")
}
})
}
shinyApp(ui = ui, server = server)