Mastering Shiny 08 User feedback

文章目录

• [8 User feedback](#8 User feedback)
• • [8.1 Validation](#8.1 Validation)
  • • [8.1.1 Validating input](#8.1.1 Validating input)
    • [8.1.2 Cancelling execution with `req()`](#8.1.2 Cancelling execution with req())
    • [8.1.3 `req()` and validation](#8.1.3 req() and validation)
    • [8.1.4 Validate output](#8.1.4 Validate output)
  • [8.2 Notifications](#8.2 Notifications)
  • • [8.2.1 Transient notification](#8.2.1 Transient notification)
    • [8.2.2 Removing on completion](#8.2.2 Removing on completion)
    • [8.2.3 Progressive updates](#8.2.3 Progressive updates)
  • [8.3 Progress bars](#8.3 Progress bars)
  • • [8.3.1 Shiny](#8.3.1 Shiny)
    • [8.3.2 Waiter](#8.3.2 Waiter)
    • [8.3.3 Spinners](#8.3.3 Spinners)
  • [8.4 Confirming and undoing](#8.4 Confirming and undoing)
  • • [8.4.1 Explicit confirmation](#8.4.1 Explicit confirmation)
    • [8.4.2 Undoing an action](#8.4.2 Undoing an action)
    • [8.4.3 Trash](#8.4.3 Trash)
  • [8.5 Summary](#8.5 Summary)

8 User feedback

8.1 Validation

8.1.1 Validating input

library(shiny);ui <- fluidPage(
  shinyFeedback::useShinyFeedback(),
  numericInput("n", "n", value = 10),
  textOutput("half")
)
server <- function(input, output, session) {
  half <- reactive({
    even <- input$n %% 2 == 0
    shinyFeedback::feedbackWarning("n", !even, "Please select an even number")
    input$n / 2    
  })
  output$half <- renderText(half())
};shinyApp(ui,server)

8.1.2 Cancelling execution with req()

ui <- fluidPage(
  selectInput("language", "Language", choices = c("", "English", "Maori")),
  textInput("name", "Name"),
  textOutput("greeting")
)
server <- function(input, output, session) {
  greetings <- c(
    English = "Hello", 
    Maori = "Kia ora"
  )
  output$greeting <- renderText({
    req(input$language, input$name)
    paste0(greetings[[input$language]], " ", input$name, "!")
  })
}
}

8.1.3 req() and validation

library(shiny);ui <- fluidPage(
  shinyFeedback::useShinyFeedback(),
  textInput("dataset", "Dataset name"), 
  tableOutput("data")
)
server <- function(input, output, session) {
  data <- reactive({
    req(input$dataset)
    exists <- exists(input$dataset, "package:datasets")
    shinyFeedback::feedbackDanger("dataset", !exists, "Unknown dataset")    
    req(exists, cancelOutput = T)
    get(input$dataset, "package:datasets")
  })
  output$data <- renderTable({
    head(data())
  })
};shinyApp(ui,server)

8.1.4 Validate output

ui <- fluidPage(
  numericInput("x", "x", value = 0),
  selectInput("trans", "transformation", 
    choices = c("square", "log", "square-root")
  ),
  textOutput("out")
)
server <- function(input, output, session) {
  output$out <- renderText({
   	if (input$x < 0 && input$trans %in% c("log", "square-root")) {
      validate("x can not be negative for this transformation")
    }
    switch(input$trans,
      square = input$x ^ 2,
      "square-root" = sqrt(input$x),
      log = log(input$x)
    )
  })
};shinyApp(ui,server)

8.2 Notifications

ui <- fluidPage(
  actionButton("goodnight", "Good night")
)
server <- function(input, output, session) {
  observeEvent(input$goodnight, { 
    showNotification("So long") 
    Sys.sleep(1)
    showNotification("Farewell")
    Sys.sleep(1)
    showNotification("Auf Wiedersehen")
    Sys.sleep(1)
    showNotification("Adieu")
  })
};shinyApp(ui,server)

8.2.1 Transient notification

8.2.2 Removing on completion

8.2.3 Progressive updates

8.3 Progress bars

8.3.1 Shiny

8.3.2 Waiter

8.3.3 Spinners

8.4 Confirming and undoing

8.4.1 Explicit confirmation

8.4.2 Undoing an action

8.4.3 Trash

8.5 Summary