从使用 insertUI 创建的模块中获取输入

Question

在我的应用程序中，我将使用insertUI 动态创建一个模块。我正在尝试找到一种方法来捕获此模块的输出。在下面的应用程序中，有一个由textInput 元素组成的简单模块。服务器部分返回此textInput 元素的值并报告它处于活动状态。我正在尝试捕获此返回值。

我试图创建一个reactiveValues 对象来获取模块的输出，但是当输入改变时这个对象似乎没有更新。模块代码本身正在运行，因为我收到来自模块内部的消息，但检查reactiveValues 的外部观察命令仅在重新创建时执行。如何从模块外部获取这些值

library(shiny)

# a module that only has a text input
moduleUI = function(id){
    ns = NS(id)
    tagList(
        # the module is enclosed within a div with it's own id to allow it's removal
        div(id = id,
            textInput(ns('text'),label = 'text'))
    )
}

# the module simply returns it's input and reports when there is a change
module = function(input,output,session){
    observeEvent(input$text,{
        print('module working')
    })
    return(input$text)
}


# ui is iniated with add/remove buttons
ui = fluidPage(
    actionButton('add','+'),
    actionButton('remove','-')
)

server = function(input, output,session) {
    # number of ui elements already created
    uiCount = reactiveVal(0)

    moduleOuts = reactiveValues()

    observeEvent(input$add,{
        # count the UI elements created to assign new IDs
        uiCount(uiCount()+1)
        # insert module UI before the add/remove buttons
        insertUI('#add',
                 'beforeBegin',
                 moduleUI(paste0("module",uiCount())))

        # failed attempt to get the output
        moduleOuts[[as.character(uiCount())]] = callModule(module,id = paste0("module",uiCount()))
    })

    observeEvent(input$remove,{
        # if remove button is pressed, remove the UI and reduce the UI count
        removeUI(
            selector = paste0("#module",uiCount())
        )
        uiCount(uiCount()-1)
    })

    # simple test
    observe({
        print(moduleOuts[['1']])
    })

    # test to get all values
    observe({
        seq_len(uiCount()) %>% sapply(function(i){
            print(moduleOuts[[as.character(i)]])
        })
    })

}


shinyApp(ui = ui, server = server)

Answer 1

这里的问题很简单：您需要显式地将值作为响应式返回。 return(reactive(input$text))

通过只返回input$text，您实际上只是在某个时间点返回它，因为input$text 只是一个值。通过将其包装在 reactive() 中，您现在将返回一个反应式表达式。服务器代码必须与之匹配，所以我在访问该值的代码中添加了()。

我删除了“简单测试”，因为它导致错误，因为该模块最初不存在。

library(shiny)

# a module that only has a text input
moduleUI = function(id){
  ns = NS(id)
  tagList(
    # the module is enclosed within a div with it's own id to allow it's removal
    div(id = id,
        textInput(ns('text'),label = 'text'))
  )
}

# the module simply returns it's input and reports when there is a change
module = function(input,output,session){
  observeEvent(input$text,{
    print('module working')
  })
  return(reactive(input$text))
}


# ui is iniated with add/remove buttons
ui = fluidPage(
  actionButton('add','+'),
  actionButton('remove','-')
)

server = function(input, output,session) {
  # number of ui elements already created
  uiCount = reactiveVal(0)

  moduleOuts = reactiveValues()

  observeEvent(input$add,{
    # count the UI elements created to assign new IDs
    uiCount(uiCount()+1)
    # insert module UI before the add/remove buttons
    insertUI('#add',
             'beforeBegin',
             moduleUI(paste0("module",uiCount())))

    # failed attempt to get the output
    moduleOuts[[as.character(uiCount())]] = callModule(module,id = paste0("module",uiCount()))
  })

  observeEvent(input$remove,{
    # if remove button is pressed, remove the UI and reduce the UI count
    removeUI(
      selector = paste0("#module",uiCount())
    )
    uiCount(uiCount()-1)
  })

  # test to get all values
  observe({
    seq_len(uiCount()) %>% sapply(function(i){
      print(moduleOuts[[as.character(i)]]())
    })
  })

}


shinyApp(ui = ui, server = server)