Shiny Modules: Handling a list of buttons - r

Question

I am trying to build an app that relies on a list of buttons created via lapply. I can successfully reference the buttons using observeEvent when I am not working with modularized code. However, when I try to use modules, the observeEvent doesn't work. I suspect it has something to do with how Shiny handles the namespace id's, but despite a couple of days of experimentation, I have not been able to solve the issue.
Below I will post first the non-modularized dummy app that does work (stolen from this other stack overflow question: R Shiny: How to write loop for observeEvent). Then I will share my existing modularized code that does not work.
Working non-modularized code:
library("shiny")
ui <- fluidPage(
fluidRow(
column(
width = 6,
lapply(
X = 1:6,
FUN = function(i) {
sliderInput(inputId = paste0("d", i), label = i, min = 0, max = 10, value = i)
}
)
),
column(
width = 6,
verbatimTextOutput(outputId = "test")
)
)
)
server <- function(input, output){
vals <- reactiveValues()
lapply(
X = 1:6,
FUN = function(i){
observeEvent(input[[paste0("d", i)]], {
vals[[paste0("slider", i)]] <- input[[paste0("d", i)]]
})
}
)
output$test <- renderPrint({
reactiveValuesToList(vals)
})
}
shinyApp(ui = ui, server = server)
Modularized Code that fails:
library(shiny)
slidersUI <- function(id){
ns <- NS(id)
tagList(
fluidRow(
column(
width = 6,
lapply(
X = 1:6,
FUN = function(i) {
sliderInput(inputId = paste0("d", i), label = i, min = 0, max = 10, value = i)
} ),
column(
width = 6,
verbatimTextOutput(outputId = "test")
)
)))
}
slidersServer <- function(input, output, session){
vals <- reactiveValues()
lapply(
X = 1:6,
FUN = function(i){
output$test2 <- renderText(paste0("this is i:", i))
observeEvent(input[[paste0("d", i)]], {
vals[[paste0("slider", i)]] <- input[[paste0("d", i)]]
})
}
)
output$test <- renderPrint({
reactiveValuesToList(vals)
})
}
library("shiny")
ui <- fluidPage(
slidersUI("TheID")
)
server <- function(input, output){
callModule(slidersServer, "TheID")
}
shinyApp(ui = ui, server = server)
Thank you!

Answer 1

You need to wrap your IDs in ns to get the correct namespace. Here is the corrected module ui:
slidersUI <- function(id){
ns <- NS(id)
tagList(
fluidRow(
column(
width = 6,
lapply(
X = 1:6,
FUN = function(i) {
sliderInput(inputId = ns(paste0("d", i)), label = i, min = 0, max = 10, value = i)
} ),
column(
width = 6,
verbatimTextOutput(outputId = ns("test"))
)
)))
}