Understanding R Shiny modules: Error in shiny::NS(id) : argument "id" is missing, with no-CodePudding

I am trying to understand the concept of shiny modules. I am attempting to modularize this very simple shinydashboard app:

ui <- dashboardPage(
  dashboardHeader(),
  dashboardSidebar(),
  dashboardBody(uiOutput("box"))
)

server <- function(input, output, session) {
  output$box <- renderValueBox({
    valueBox(
      subtitle = "Hi",
      value = 2
    )
  })
}

shinyApp(ui, server)

which works as desired.

However, when modularizing I keep getting the following mistake: Error in shiny::NS(id) : argument "id" is missing, with no default.

#### Modules ####
costumizedValueBox <- function(id) {
  ns <- shiny::NS(id)
  uiOutput(ns("box"))
}

costumizedValueBoxServer <- function(id) {
  moduleServer(
    id,
    function(input, output, session) {
      output$box <- renderValueBox({
        valueBox(
          subtitle = "Hi",
          value = 2
        )
      })
    }
  )
}

#### App ####
ui <- dashboardPage(
  dashboardHeader(),
  dashboardSidebar(),
  dashboardBody(costumizedValueBox())
)

server <- function(input, output, session) {
  costumizedValueBoxServer()
}

shinyApp(ui, server)

I have tried different modifications of the modularized code, none of which worked, e. g. changing the output (to textOutput) or the general setup. The error message suggests a problem with the NS function but I am not able to figure it out.

Thanks!

CodePudding user response：

Modules (i.e., costumizedValueBoxServer and costumizedValueBox) are functions with a required argument.

ui <- dashboardPage(
  dashboardHeader(),
  dashboardSidebar(),
  dashboardBody(costumizedValueBox("my_id")) # pass in an ID
)

server <- function(input, output, session) {
  costumizedValueBoxServer("my_id") # pass in the same ID
}

CodePudding user response：

This is what @Limey describes in the comments: To learn in detail see here https://shiny.rstudio.com/articles/modules.html

library(shiny)

#### Modules ####
costumizedValueBox <- function(id, label = "ValueBox_custom") {
  ns <- shiny::NS(id)
  uiOutput(ns("box"))
}

costumizedValueBoxServer <- function(id) {
  moduleServer(
    id,
    function(input, output, session) {
      output$box <- renderValueBox({
        valueBox(
          subtitle = "Hi",
          value = 2
        )
      })
    }
  )
}

#### App ####
ui <- dashboardPage(
  dashboardHeader(),
  dashboardSidebar(),
  dashboardBody(costumizedValueBox("ValueBox_custom1"))
)

server <- function(input, output, session) {
  costumizedValueBoxServer("ValueBox_custom1")
}

shinyApp(ui, server)