r - 通过 selectInput 或 actionButton 更改选择

Question

我正在设计一个 Shiny 应用程序来分析调查结果，我希望用户能够从 selectInput 下拉菜单(“跳转到选择”)或通过单击 actionButtons(“上一个”、“下一个”)。这些文章是一个有用的起点:

https://shiny.rstudio.com/reference/shiny/1.0.4/reactiveVal.html

https://shiny.rstudio.com/articles/action-buttons.html

我的问题是 selectInput 与 actionButtons 的结果冲突，因为两者控制的是同一个对象。我如何让他们一起工作？我不想将 isolate() 与 selectInput 一起使用并让用户点击一个额外的按钮；我希望选择在他们选择后立即更改。谢谢!

library(shiny)

ui <- fluidPage(

   mainPanel(

     actionButton("previous_q", 
                  "Previous"), 
     actionButton("next_q", 
                  "Next"), 
     selectInput("jump", 
                 "Jump to Question", 
                 choices = 1:10), 
     textOutput("selected")

   )
)

server <- function(input, output) {

  # Select based on "Previous" and "Next" buttons -------

  selected <- reactiveVal(1)

  observeEvent(input$previous_q, {

    newSelection <- selected() - 1
    selected(newSelection)

  })

  observeEvent(input$next_q, {

    newSelection <- selected() + 1
    selected(newSelection)

  })

  # Jump to selection (COMMENTED OUT SO APP DOESN'T CRASH) ----------------

  #observeEvent(input$jump, {

    #newSelection <- input$jump
    #selected(newSelection)

  #})

  # Display selected

  output$selected <- renderText({ 
    paste(selected())                     
  })
}

shinyApp(ui = ui, server = server)

Answer 1

问题是input$jump是一个字符串，不是一个数字。做:

  observeEvent(input$jump, {

    newSelection <- as.integer(input$jump)
    selected(newSelection)

  })