闪亮的模块:在创建模块UI时已经存储了参数(附加参数)，而不是将其传递给模块的服务器功能? [英] shiny modules: Store parameters (additional argument) already when creating module-UI instead of passing it to module's server function?

问题描述

我创建了一个模块sliderCheckbox，该模块将sliderInput和checkBoxInput捆绑在一起以禁用slideInput-基本上可以说出我不知道"，这对于类似调查的输入是必需的.当禁用滑块时，我希望它返回默认值-通常是初始值，但不一定.

I have created a module sliderCheckbox which bundles together a sliderInput and a checkBoxInput to disable the sliderInput - basically a possibility to state "I don't know", which is necessary for survey-like inputs. When the slider is disabled, I want it to return a default value - most often the initial value, but not necessarily.

现在我的问题是:是否有可能在初始化UI时通过sliderCheckboxInput()传递此默认值?由于默认值是最小值和最大值之类的属性，因此它在逻辑上所属的位置，并且也更适合我的其余设置.

Now my question is: Is there any possibility to pass this default value when initialising the UI, that is with sliderCheckboxInput()? As the default value is a property like minimum and maximum, that is where it logically belongs to, and it also fits better to the rest of my setup.

示例:

library(shiny)
library(shinyjs)

sliderCheckboxInput <- function(id,description="",
                                min = 0,
                                max = 100,
                                value = 30,
                                default= NULL ##HERE I would want the default value to be set
                                cb_title = "I don't know"){
  ns <- NS(id)

  fluidRow(
    column(width=9,
           sliderInput(ns("sl"),
                       paste0(description, collapse=""),
                       min = min,
                       max = max,
                       value = value)
    ),
    column(width=2,
           checkboxInput(ns("active"),
                         cb_title, value=FALSE )
    )
  )
}

sliderCheckbox<- function(input, output, session,
                          default=NA) { #Problem: set default when initialising module

  oldvalue<- reactiveVal()

  observeEvent(input$active, {
    if (input$active){
      oldvalue(input$sl)
      disable("sl")
      updateSliderInput(session, "sl", value=default)
    }else {
      updateSliderInput(session, "sl", value=oldvalue())
      enable("sl")
    }

    toggleState("sl", !input$active)
  })

  onclick("sl",
          if(input$active) updateCheckboxInput(session, "active", value=FALSE)
  )

  return ( reactive({
    if (input$active){
      default
    }else {
      input$sl
    }
  }))

}


ui <- fluidPage(

  useShinyjs(),

  # Sidebar with a slider input for number of bins
  sidebarLayout(
    sidebarPanel(
      sliderCheckboxInput("bins", "Number of bins:",
                          min = 1,
                          max = 50,
                          value = 30)
    ),

    # Show a plot of the generated distribution
    mainPanel(
      plotOutput("distPlot")
    )
  )
)

server <- function(input, output, session) {
  bins_nr <- callModule(sliderCheckbox, "bins", default=44)

  output$distPlot <- renderPlot({

    # generate bins based on input$bins from ui.R
    x    <- faithful[, 2]
    bins <- seq(min(x), max(x), length.out = bins_nr() + 1)

    # draw the histogram with the specified number of bins
    hist(x, breaks = bins, col = 'darkgray', border = 'white')

  })

}

shinyApp(ui, server)

推荐答案

您可以使用隐藏的textInput

library(shiny)
library(shinyjs)

sendValueToServer <- function(id, value) {
  hidden(textInput(
    id, "If you can see this, you forgot useShinyjs()", value
  ))
}

myModuleUI <- function(id, param) {
  ns <- NS(id)
  tagList(
    sendValueToServer(ns("param_id"), param),
    textOutput(ns("text_out"))
  )
}

myModule <- function(input, output, session) {
  param <- isolate(input$param_id)

  output$text_out <- renderText({
    param
  })
}

shinyApp(
  ui = fluidPage(
    useShinyjs(),
    myModuleUI("id", "test")
  ),
  server = function(input, output, session) {
    callModule(myModule, "id")
  }
)

使用Shiny的JavaScript API可能有更直接的方法，但这是一个纯R"解决方案，对于大多数用例来说应该足够了.请注意，您可以在初始化时使用输入值

There are probably more direct ways to do this using the JavaScript API of shiny but this is a "pure R" solution which should be enough for most usecases. Note that you can use the input value at initialization time with

isolate(input$text_in)

因为ui总是在服务器之前构建的.如果将所有内容都包裹在renderUI中，事情会变得更加复杂，但这对您而言似乎并非如此.

because the ui is always built before the server. Things get more complicated if everything is wrapped into renderUI but this does not seem to be the case for you.

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