Make shiny module reactive

Question

The example app below has two shiny modules. The first module displays a table with randomly generated values as well as an action button, which, when clicked, generates new values. The second module displays the data set generated in the first one.

How do I make the second table change with the first one?

Thank you.

app.R

library(shiny)
source("modules.R")

ui <- fluidPage(

  fluidRow(
    column(6, table1_moduleUI("table1")),
    column(6, table2_moduleUI("table2"))

  )

)

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

  table1 <- callModule(table1_module, "table1")
  callModule(table2_module, "table2", table_data = table1$values)
}

shinyApp(ui, server)

modules.R

# Module for table 1

table1_moduleUI <- function(id){
  ns <- NS(id)

  tagList(
    tableOutput(ns("table")),
    actionButton(ns("submit"), label = "Change values")
  )
}

table1_module <- function(input, output, session) {

  table <- reactiveValues()

  observeEvent(input$submit, {
    table$values <- replicate(3, rnorm(10))
  }, ignoreNULL = FALSE)

  output$table <- renderTable({
    table$values
  })

  return(table)
}

# Module for table 2

table2_moduleUI <- function(id){

  ns <- NS(id)
  tableOutput(ns("table"))
}

table2_module <- function(input, output, session, table_data){

  output$table <- renderTable({
    table_data
  })
}

Seems like the code for the second module is missing. – Sada93 Apr 11 '19 at 01:30 — Sada93, Apr 11 '19 at 01:30

score 2 · Accepted Answer · answered Apr 11 '19 at 01:46

The second module seems to be missing in the question but the logic seems to be straight forward. The issue here is that you are passing the value of the reactive expression to the second module when you use,

callModule(table2_module, "table2", table_data = table1$values)

instead, you want to pass the reactive value, which tells R to invalidate the outputs when the reactive values changes,

callModule(table2_module, "table2", table_data = table1)

here is the complete app,

library(shiny)

# Module for table 1

table1_moduleUI <- function(id){
  ns <- NS(id)

  tagList(
    tableOutput(ns("table")),
    actionButton(ns("submit"), label = "Change values")
  )
}

table2_moduleUI <- function(id){
  ns <- NS(id)
  tableOutput(ns("table"))
}

table1_module <- function(input, output, session) {

  table <- reactiveValues()

  observeEvent(input$submit, {
    table$values <- replicate(3, rnorm(10))
  }, ignoreNULL = FALSE)

  output$table <- renderTable({
    table$values
  })

  return(table)
}

table2_module <- function(input, output, session,table_data) {

  output$table <- renderTable({
    table_data
  })

}


ui <- fluidPage(

  fluidRow(
    column(6, table1_moduleUI("table1")),
    column(6, table2_moduleUI("table2"))
  )

)

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

  table1 <- callModule(table1_module, "table1")
  callModule(table2_module, "table2", table_data = table1$values)
}

shinyApp(ui, server)

As a caveat, if you are wanting to display a dataframe, using reactive values seems to be overkill. When we want to return a reactive expression, intead of initializing a reactive variable and setting it in an observer we can simply use reactive() or eventReactive(), this is what they are there for! So let's use it. Reactive values have their space, and in my experience are used relatively sparingly.

library(shiny)

# Module for table 1

table1_moduleUI <- function(id){
  ns <- NS(id)

  tagList(
    tableOutput(ns("table")),
    actionButton(ns("submit"), label = "Change values")
  )
}

table2_moduleUI <- function(id){
  ns <- NS(id)
  tableOutput(ns("table"))
}

table1_module <- function(input, output, session) {

  table = eventReactive(input$submit, {
    replicate(3, rnorm(10))
  }, ignoreNULL = FALSE)

  output$table <- renderTable({
    table()
  })

  return(table)
}

table2_module <- function(input, output, session,table_data) {

  output$table <- renderTable({
    table_data()
  })

}


ui <- fluidPage(

  fluidRow(
    column(6, table1_moduleUI("table1")),
    column(6, table2_moduleUI("table2"))
  )

)

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

  table1 <- callModule(table1_module, "table1")
  callModule(table2_module, "table2", table_data = table1)
}

shinyApp(ui, server)

Make shiny module reactive

1 Answers1