How to: use shiny.fluent with Shiny modules

Shiny.fluent components work in Shiny modules out of the box. In this example, a calculator module defined by calcUI() and calcServer() allows the user to choose a mathematical operation and input two numeric values. The server function returns a reactive value with the result.

A few things to note:

• The ns() function is used to wrap the IDs of the inputs in the module UI, but not when accessing them via input$ in the module server.
• The calcUI() and calcServer() are called with the same ID in the UI and server parts of the Shiny app.

library(shiny)
library(shiny.fluent)

calcModes <- list(
  list(key = "add", text = "Addition"),
  list(key = "mul", text = "Multiplication")
)

calcUI <- function(id) {
  ns <- NS(id)
  div(style = "margin: 15px 0px 15px",
    ChoiceGroup(ns("mode"), label = "Operation", value = "add", options = calcModes),
    Label("Values"),
    flowLayout(
      SpinButton(ns("a"), label = "A = ", value = 3),
      SpinButton(ns("b"), label = "B = ", value = 5)
    )
  )
}

calcServer <- function(id) {
  moduleServer(id, function(input, output, session) {
    result <- reactive({
      switch(req(input$mode),
        add = input$a + input$b,
        mul = input$a * input$b
      )
    })
    return(result)
  })
}

shinyApp(
  ui = fluidPage(
    calcUI("calc"),
    textOutput("result")
  ),
  server = function(input, output) {
    result <- calcServer("calc")
    output$result <- renderText(
      paste("The module returned", result())
    )
  }
)