only last modal shows when multiple modals are triggered by the same event

[ifoxfoot]

• Edit to add that including a return statement in the loop causes modal one to pop up but not modal two.

System details

Browser Version: Chrome Version 113.0.5672.92 Output of sessionInfo():

R version 4.2.3 (2023-03-15)
Platform: x86_64-apple-darwin17.0 (64-bit)
Running under: macOS Monterey 12.6.3

Matrix products: default
LAPACK: /Library/Frameworks/R.framework/Versions/4.2/Resources/lib/libRlapack.dylib

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] shiny_1.7.4  cowsay_0.8.2

loaded via a namespace (and not attached):
 [1] Rcpp_1.0.10      rmsfact_0.0.3    withr_2.5.0      digest_0.6.31    crayon_1.5.2    
 [6] later_1.3.1      mime_0.12        R6_2.5.1         jsonlite_1.8.4   lifecycle_1.0.3 
[11] xtable_1.8-4     magrittr_2.0.3   cachem_1.0.8     rlang_1.1.1      cli_3.6.1       
[16] rstudioapi_0.14  promises_1.2.0.1 jquerylib_0.1.4  bslib_0.4.2      ellipsis_0.3.2  
[21] fortunes_1.5-4   tools_4.2.3      httpuv_1.6.11    fastmap_1.1.1    compiler_4.2.3  
[26] memoise_2.0.1    htmltools_0.5.5  sass_0.4.6      

Example application or steps to reproduce the problem

click show modal. Only Warning Two shows up.

library(shiny)

mess_fun <- function() {
  message("WARNING ONE")
  message("WARNING TWO")
}

shinyApp(
  ui = basicPage(
    actionButton("show", "Show modal dialog")
  ),
  server = function(input, output) {

    observeEvent(input$show, {
      warning_list <- list()
      withCallingHandlers(
        mess_fun(),
        message=function(w) {warning_list <<- c(warning_list, list(w$message))})
      for (i in warning_list) {
        showModal(modalDialog(i)) }
    })

  }
)

Describe the problem in detail

In my code, ideally modal one should pop up, and when it is dismissed, modal two should pop up. However, only modal two pops up.

[stla]

Not sure it's possible like this, I don't know.

Alternatively, you could use two observers, as in the last example of ?shiny::modalDialog. Or you can use the shinyalert package, which allows to chain the alerts.

[ifoxfoot]

Hi @stla yeah I'm not sure it is possible either, but yes it works using shinyalert. I suppose if it's not possible this is more of a feature request...

[ismirsehregal]

I guess the issue here is, that shiny's modals always get the same id: "shiny-modal" (also shown here - please see the "multiple modals" edit).

However, you could re-trigger the observer after closing the first modal as long as items are in the list - something like this:

library(shiny)

mess_fun <- function() {
  message("WARNING ONE")
  message("WARNING TWO")
}

shinyApp(
  ui = basicPage(actionButton("show", "Show modal dialog")),
  server = function(input, output, session) {
    warning_list <- list() # consider using a reactiveVal instead
    withCallingHandlers(
      mess_fun(),
      message = function(w) {
        warning_list <<- c(warning_list, list(w$message))
      }
    )
    
    observeEvent(c(input$show, input$dismiss), {
      if(length(warning_list) == 0 && input$dismiss == 1) {
        removeModal()
      }
      if(length(warning_list) > 0 && (is.null(input$dismiss) || input$dismiss > 0)){
        showModal(modalDialog(warning_list[[1]], footer = actionButton("dismiss", "Dismiss")))
        warning_list[[1]] <<- NULL
      }
    }, ignoreInit = TRUE)
  }
)

PS: personally I'd show both (or multiple) warnings using the same modal instead.