Question

显示validate()函数的工作example app from the shiny docs：

## server.R

`%then%` <- shiny:::`%OR%`

shinyServer(function(input, output) {

  data <- reactive({
    validate(
      need(input$data != "", "Please select a data set") %then%
      need(input$data %in% c("mtcars", "faithful", "iris"),
        "Unrecognized data set") %then%
      need(input$data, "Input is an empty string") %then%
      need(!is.null(input$data),
        "Input is not an empty string, it is NULL")
    )
    get(input$data, 'package:datasets')
  })

  output$plot <- renderPlot({
    hist(data()[, 1], col = 'forestgreen', border = 'white')
  })

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

})

## ui.R

shinyUI(fluidPage(

  tags$head(
    tags$style(HTML("
      .shiny-output-error-validation {
        color: green;
      }
    "))
  ),

  titlePanel("Validation App"),

  sidebarLayout(
    sidebarPanel(
      selectInput("data", label = "Data set",
        choices = c("", "mtcars", "faithful", "iris"))
    ),

    # Show a plot of the generated distribution
    mainPanel(
      plotOutput("plot"),
      tableOutput("table")
    )
  )
))

有没有办法让应用只显示一次validate错误消息而不是两次，因为相同的验证对plot失败一次，对{失败一次失败{1}}元素？

Answer 1

我想应该有更好的方法来解决这个问题，但这是我唯一的想法：

server.R

     ## server.R

    `%then%` <- shiny:::`%OR%`

    shinyServer(function(input, output) {
            values <- reactiveValues(test=data.frame())
            data <- reactive({
                    validate(
                            need(input$data != "", "Please select a data set") %then%
                                    need(input$data %in% c("mtcars", "faithful", "iris"),
                                         "Unrecognized data set") %then%
                                    need(input$data, "Input is an empty string") %then%
                                    need(!is.null(input$data),
                                         "Input is not an empty string, it is NULL")
                    )
                    get(input$data, 'package:datasets')
            })
            observeEvent(data(), {
                    if(!is.null(data())) {
                            values$test <- data()
                    } else {
                            values$test <- NULL
                    }
            })

            output$plot <- renderPlot({
                    hist(data()[, 1], col = 'forestgreen', border = 'white')
            })

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

    })

仅显示验证错误消息一次

1 个答案: