Modularize your Shiny Apps: Solutions

# load package
library(shiny)

####################
#                  #
#    Exercise 1    #
#                  #
####################
q1_module_UI <- function(id) {
  ns <- NS(id)
  selectInput(
    inputId = ns("letter"),
    label = "Select a letter",
    choices = LETTERS
  )
}

####################
#                  #
#    Exercise 2    #
#                  #
####################
q1_module <- function(input, output, session) {
  observe(print(input$letter))
}

####################
#                  #
#    Exercise 3    #
#                  #
####################
ui <- fluidPage(q1_module_UI(id = "q1"))

####################
#                  #
#    Exercise 4    #
#                  #
####################
server <- function(input, output, session) {
  callModule(module = q1_module, id = "q1")
}

shinyApp(ui = ui, server = server)

####################
#                  #
#    Exercise 5    #
#                  #
####################
q5_module_UI <- function(id) {
  ns <- NS(id)
  tagList(
    selectInput(
      inputId = ns("letter"),
      label = "Select a letter",
      choices = LETTERS
    ),
    textOutput(outputId = ns("selected_letter"))
  )
}

q5_module <- function(input, output, session) {
  output$selected_letter <- renderText(paste("You selected", input$letter))
}

shinyApp(
  ui = fluidPage(q5_module_UI(id = "q5")),
  server = function(input, output, session) {
    callModule(module = q5_module, id = "q5")
  }
)

####################
#                  #
#    Exercise 6    #
#                  #
####################
shinyApp(
  ui = fluidPage(
    q5_module_UI(id = "q5_a"), br(),
    q5_module_UI(id = "q5_b")
  ),
  server = function(input, output, session) {
    callModule(module = q5_module, id = "q5_a")
    callModule(module = q5_module, id = "q5_b")
  }
)

####################
#                  #
#    Exercise 7    #
#                  #
####################
q7_module_UI <- function(id, label = "Select a letter") {
  ns <- NS(id)
  tagList(
    selectInput(
      inputId = ns("letter"),
      label = label,
      choices = LETTERS
    ),
    textOutput(outputId = ns("selected_letter"))
  )
}

q7_module <- function(input, output, session) {
  output$selected_letter <- renderText(paste("You selected", input$letter))
}

shinyApp(
  ui = fluidPage(q7_module_UI(id = "q7", label = "Your letter goes here")),
  server = function(input, output, session) {
    callModule(module = q7_module, id = "q7")
  }
)

####################
#                  #
#    Exercise 8    #
#                  #
####################
q8_module_UI <- function(id, subjects, button_label = "Submit!") {
  ns <- NS(id)
  tagList(
    textInput(inputId = ns("name"), label = "Name"),
    selectInput(inputId = ns("subject"), label = "Subject", choices = subjects),
    textAreaInput(inputId = ns("message"), label = "Message"),
    actionButton(inputId = ns("submit"), label = button_label)
  )
}

q8_module <- function(input, output, session) {
  observeEvent(input$submit, {
    content <- paste(input$name, input$subject, input$message, "\n", sep = "\n")
    write(x = content, file = "content.txt", append = T)
  })
}

shinyApp(
  ui = fluidPage(
    q8_module_UI(
      id = "q8",
      subjects = c("Question", "Suggestion"),
      button_label = "Send"
    )
  ),
  server = function(input, output, session) {
    callModule(module = q8_module, id = "q8")
  }
)

####################
#                  #
#    Exercise 9    #
#                  #
####################
q9_module_UI <- function(id) {
  ns <- NS(id)
  tagList(
    numericInput(
      inputId = ns("element_num"),
      label = "Number of elements",
      value = 3
    ),
    uiOutput(outputId = ns("elements"))
  )
}

q9_module <- function(input, output, session) {
  output$elements <- renderUI({
    tagList(
      lapply(1:input$element_num, function(i) {
        textInput(inputId = paste0("element", i), label = paste0("Element", i))
      })
    )
  })
}

shinyApp(
  ui = fluidPage(q9_module_UI(id = "q9")),
  server = function(input, output, session) {
    callModule(module = q9_module, id = "q9")
  }
)

####################
#                  #
#    Exercise 10   #
#                  #
####################

q10_module_inner_UI <- function(id) {
  ns <- NS(id)
  textOutput(outputId = ns("inner_text"))
}

q10_module_inner <- function(input, output, session, text) {
  output$inner_text <- renderText(paste("Your text:", text))
}

q10_module_outer_UI <- function(id) {
  ns <- NS(id)
  q10_module_inner_UI(id = ns("q10_inner"))
}

q10_module_outer <- function(input, output, session, text) {
  callModule(module = q10_module_inner, id = "q10_inner", text = text)
}

shinyApp(
  ui = fluidPage(q10_module_outer_UI(id = "q10_outer")),
  server = function(input, output, session) {
    callModule(module = q10_module_outer, id = "q10_outer", text = "Hello")
  }
)