Shinyjs 无法正确启用/禁用 UI 元素答案

【问题标题】：Shinyjs cant enable/disable UI element properlyShinyjs 无法正确启用/禁用 UI 元素
【发布时间】：2019-11-14 23:02:02
【问题描述】：

我有以下闪亮的应用程序

library(shiny)
runApp(shinyApp(
    ui = fluidPage(
        shinyjs::useShinyjs(),
       selectizeInput(inputId = "aaa", label = NULL, choices = c('a', 'b', 'c', 'd', 'e', 'f'), selected = NULL, width = '90%',
                         options = list(placeholder = 'Get', 
                                                onInitialize = I('function() { this.setValue(""); }'), maxItems = 5)),
       radioButtons("bbb", label = NULL, inline = TRUE, width = "100%", selected = 95,
                                                        choiceValues = list(1, 2, 3),
                                                        choiceNames = list(
                                                                            div(style = "font-size:24px;", "1%"), 
                                                                            div(style = "font-size:24px;", "2%"), 
                                                                            div(style = "font-size:24px;", "3%")
                                                                          ))
    ),
    server = function(input, output, session) {
        observeEvent(input$aaa, {
            if(grepl("a", input$aaa)){
                shinyjs::enable("bbb")
            }else{
                shinyjs::disable("bbb")
            }
        })
    }
))

当我选择a, b, c, 时，Radiobutton 启用，现在如果我删除所有选择，我仍然看到启用。这对我来说很奇怪，因为我希望它会被禁用。然后在删除所有内容后，如果我在没有a 的情况下重新选择，那么它仍然保持启用状态。

谁能告诉我哪里出了问题？

【问题讨论】：

标签： shiny shiny-server shinyjs

【解决方案1】：

我做了两个更改，它几乎可以按照您的意愿工作： - 将单选按钮初始化为禁用 - 只将一个真/假传递给 if

library(shiny)
library(shinyjs)
runApp(shinyApp(
  ui = fluidPage(
    shinyjs::useShinyjs(),
    selectizeInput(inputId = "aaa", label = NULL, choices = c('a', 'b', 'c', 'd', 'e', 'f'), selected = NULL, width = '90%',
                   options = list(placeholder = 'Get', 
                                  onInitialize = I('function() { this.setValue(""); }'), maxItems = 5)),
    shinyjs::disabled( # buttons disable at the launching
      radioButtons("bbb", label = NULL, inline = TRUE, width = "100%", selected = 95,
                   choiceValues = list(1, 2, 3),
                   choiceNames = list(
                     div(style = "font-size:24px;", "1%"), 
                     div(style = "font-size:24px;", "2%"), 
                     div(style = "font-size:24px;", "3%")
                   ))
    )

  ),
  server = function(input, output, session) {
    observeEvent(input$aaa, {
      # any(grepl(...)) returns TRUE if one of them is TRUE
      # just grepl(..) would return a vector of TRUE and FALSE
      if(any(grepl("a", input$aaa))){
        shinyjs::enable("bbb")
      }else{
        shinyjs::disable("bbb")
      }
    })
  }
))

我不知道为什么在选择“a”后没有选择任何内容时按钮一直处于启用状态

编辑：当输入具有值然后为 NULL 时，observeEvent 似乎没有反应。改用observe() 可以解决问题。

library(shiny)
library(shinyjs)
runApp(shinyApp(
  ui = fluidPage(
    shinyjs::useShinyjs(),
    selectizeInput(inputId = "aaa", label = NULL, choices = c('a', 'b', 'c', 'd', 'e', 'f'), selected = NULL, width = '90%',
                   options = list(placeholder = 'Get', 
                                  onInitialize = I('function() { this.setValue(""); }'), maxItems = 5)),
    shinyjs::disabled(
      radioButtons("bbb", label = NULL, inline = TRUE, width = "100%", selected = 95,
                   choiceValues = list(1, 2, 3),
                   choiceNames = list(
                     div(style = "font-size:24px;", "1%"), 
                     div(style = "font-size:24px;", "2%"), 
                     div(style = "font-size:24px;", "3%")
                   ))
    )

  ),
  server = function(input, output, session) {

    observe({
        if(any(grepl("a", input$aaa))){
          shinyjs::enable("bbb")
        }else{
          shinyjs::disable("bbb")
        }
      }
    )
  }
))

【讨论】：