r - How to create a login page in shiny?

The goal is to have a shiny module ui1.R that loads a second module ui2.R when the button confirm is clicked. I think the issue is that is.null(input$confirm) is always invalidated. What I need instead, is to invalidate the expression only once confirm is clicked.

The question is very close to Starting Shiny app after password input, but I am trying to modularize the solution.

ui.R

library(shiny)
library(shinyjs)
htmlOutput("page")

server.R

rm(list = ls())
library(shiny)
library(dplyr)
library(shinyjs)
Logged <-  FALSE

shinyServer(function(input, output) {

  source('ui1.R') #login page

  source('ui2.R')


  observeEvent(!is.null(input$confirm), {
    Logged <<- T
  })

  observe({
    if (Logged == FALSE) {
      output$page <- renderUI({ 

        ui1Output('ui1Output') 
      })
      output$lsuId <- renderText({ input$lsuId })
    }
    if (Logged == TRUE) 
    {
      output$page <- renderUI({ ui2 })
    }
  })
  callModule(ui1,'ui1') 

})

ui1.R

library(shinyjs)

ui1Output <-  function(id, label = "ui1") {
  ns <- NS(id)
  shinyUI(fluidPage(

    useShinyjs(),
    titlePanel("Form"),
    div(textInput(ns("lsuId"), "This has to be filled", ""),
      actionButton(ns("confirm"), "Submit", class = "btn-primary")
    )
  ))
}

ui1 <- function(input, output, session) {
  observe({

    LSUID <- reactive({ input$lsuId })
    shinyjs::toggleState(id = "confirm", condition = LSUID())
  })
}

ui2.R

ui2<-  shinyUI(fluidPage(
 div("well done!")

))

global.R

source('ui1.R') #login page
source('ui2.R')

Answer

I think you have two issues here:

First your confirm button value is stored here: input$"ui1Output-confirm" and not here: input$confirm

I would suggest to replace:

observeEvent(is.null(input$confirm), {
  Logged <<- F
})

By:

observeEvent(input$"ui1Output-confirm", {
    Logged <<- T
})

Then your observe function does not contain any reference to the button so it is not executed when the user clicks on it. I don't have a proper solution for this but a simple hack would be to add:

tmp <- input$"ui1Output-confirm"

at the begining of the observe section:

observe({
    tmp <- input$"ui1Output-confirm"

    if (Logged == FALSE) {
        output$page <- renderUI({ 
            ui1Output('ui1Output') 

        })
        output$lsuId <- renderText({ input$lsuId })
    }
    if (Logged == TRUE) 
    {
         output$page <- renderUI({ ui2 })
    }
})