Modal dialog prompt for inputs in Shiny. #r #shiny

modal_dialog_input_1.R

library(shiny)

shinyApp(
  ui = basicPage(
    actionButton("show", "Show modal dialog"),
    verbatimTextOutput("print")
  ),
  
  server = function(input, output) {
    
    vals <- reactiveValues(txt = NULL)
    
    # Create modal
    popupModal <- function(failed = FALSE) {
      modalDialog(
        textInput("txt", "Write something"),
        if (failed)
          div(tags$b("You did not input anything", style = "color: red;")),
        
        footer = tagList(
          modalButton("Cancel"),
          actionButton("ok", "OK")
        )
      )
    }
    
    # Show modal when button is clicked.
    observeEvent(input$show, {
      showModal(popupModal())
    })
    
    observeEvent(input$ok, {
  
      if (!is.null(input$txt) && nzchar(input$txt)) {
        vals$txt <- input$txt
        removeModal()
      } else {
        showModal(popupModal(failed = TRUE))
      }
    })
    
    # Print inputted text
    output$print <- renderPrint({
      if (is.null(vals$txt))
        "No data selected"
      else
        vals$txt
    })
  }
)

modal_dialog_input_2.R

library(shiny)

shinyApp(
  ui = basicPage(
    actionButton("show", "Show modal dialog"),
    verbatimTextOutput("print")
  ),
  
  server = function(input, output) {
    
    # Create object to store reactive values
    vals <- reactiveValues(
      txt = NULL,
      error_msg = NULL,
      print = FALSE
    )
    
    # Create modal
    popupModal <- function() {
      modalDialog(
        textInput("txt", "Write something"),
        
        textOutput("skip_error_msg"),
        
        footer = tagList(
          modalButton("Cancel"),
          actionButton("ok", "OK")
        )
      )
    }
    
    # Show modal when button is clicked
    observeEvent(input$show, {
      vals$error_msg <- NULL
      showModal(popupModal())
    })
    
    # Validate submission
    observeEvent(input$ok, {
      vals$txt <- input$txt
      
      if (!is.null(vals$txt) && nzchar(vals$txt)) {
        removeModal()
        vals$print <- TRUE
      } else {
        vals$error_msg <- "You did not input anything."
      }
    })
    
    # Output error message
    output$skip_error_msg <- renderText({
      vals$error_msg
    })
    
    # Output inputted text
    output$print <- renderPrint({
      if (vals$print) {
        vals$txt
      } else {
        NULL
      }
    })
  }
)