无法获得flexdashboard模态Shiny反应性来处理NULL状态

首先,这是一个可重复性最小的例子:

假设我有以下flexdashboard应用程序示例.Rmd:

---
title: "Test App"
output:
  flexdashboard::flex_dashboard:
    theme: ["lumen"]
    orientation: ["columns"]
runtime: shiny
---

```{r setup, include=FALSE}
source('modules.R')
```

Test
==================

Inputs {.sidebar data-width=250}
------------------

```{r}

## Modules:
globalInputs <- callModule(setup, "inputs")  # Note: you only need to call this one time!
callModule(chart, "modalChart", globalInputs)
## UI:
sidebar("inputs")

```

Column
-------------------------------------

### ModalTest

```{r}
chartUI2("modalChart")
```

这是我的modules.R文件:

sidebar <- function(id) {
  ns <- NS(id)
  tagList(
    helpText("Press the button below to pull up a modal:"),
    actionButton(ns("settings"), "Settings", icon = icon("cogs"), width = '100%')
  )
}

# setup function
setup <- function(input, output, session) {
  return(input)  ## Note, input in this case is a reactive list of values that you can index against with $or [[""]]
}

# UI module for the popup Settings modal
modalUI <- function(id) {
  ns <- NS(id)
  withTags({  # UI elements for the modal go in here
    ## Note: you can use the fluidPage() and fluidRow() functions to define a column-based UI for the chart inputs below:
    fluidPage(
      fluidRow(sliderInput(ns("bins"), "Number of bins:",
                           min = 1,  max = 50, value = 30),
               textInput(ns("plotTitle"), label = "Plot Title", value = "This is a test")
      ))
  })
}


## UI module for the 2 buttons in the modal:
modalFooterUI <- function(id) {
  ns <- NS(id)
  tagList(
    modalButton("Cancel", icon("remove")),
    actionButton(ns("modalApply"), "Apply", icon = icon("check"))
  )
}

## chart module ----------------------------------------------------------------
chartUI2 <- function(id) {
  ns <- NS(id)
  plotOutput(ns("distPlot"))
}

chart <- function(input, output, session, setup) {

  observeEvent(setup$settings, {
    showModal(modalDialog(
      modalUI("inputs"),  # Call UI function defined in './modules/modal.R'; note the namespace 'inputs' is the same globally for the app
      title = "Settings",
      footer = modalFooterUI("inputs"),
      size = "l",
      easyClose = TRUE,
      fade = TRUE)
    )
  })

  output$distPlot <- renderPlot({
    if (setup$settings == 0)
      return(
        hist(faithful[, 2],
             breaks = 5,  # if the button hasn't been pressed, default
             main = 'This is the default title',
             col = 'darkgray',
             border = 'white')
      )
    isolate({
      x <- faithful[, 2]
      bins <- setup$bins
      hist(x,
           breaks = bins,
           main = setup$plotTitle,
           col = 'darkgray',
           border = 'white')
    })

  })
}

这就是我想要完成的事情:

>页面加载时使用默认参数渲染distPlot.这应该总是发生.
>当我单击“设置”动作按钮时,它会弹出模态覆盖(但将背景中的绘图保持为原始状态)
>允许用户更改弹出模式中的参数,但在用户点击“应用”按钮之前不要重新渲染绘图.

我想我已经#1想通了,但是当我点击’设置’按钮时,我得到一个错误’breaks(x)’产生的无效断点:NULL.然后,我改变输入,它什么都不做(除非我再次点击Settings actionButton(这反过来渲染了给定输入的图).

我究竟做错了什么?

谢谢!!

最佳答案 可能存在时间问题.当您按下设置按钮时,setup $settings变为1,因此renderPlot会尝试重新绘制.如果在设置滑块之前发生这种情况,则设置$bins为NULL并且您收到错误.

只有当用户按下模态中的“应用”按钮时,您才可以在renderPlot的第一个if中添加条件以使用setup $bins进行绘图:

output$distPlot <- renderPlot({
    if (setup$settings == 0 | !isTruthy(setup$modalApply)) {
        hist(faithful[, 2],
             breaks = 5,  # if the button hasn't been pressed, default
             main = 'This is the default title',
             col = 'darkgray',
             border = 'white')
      } else {
    isolate({
      x <- faithful[, 2]
      bins <- setup$bins
      hist(x,
           breaks = bins,
           main = setup$plotTitle,
           col = 'darkgray',
           border = 'white')
    })

!如果setup $modalApply为NULL(尚未创建模态)或者为0(用户尚未按下按钮),则isTruthy将为TRUE.
用户按下“应用”按钮后,将更新绘图.

编辑:

为了方便起见,您可以使用reactiveValues来保存所有绘图参数,包括默认参数.当用户单击“应用”按钮时,可以更新它,然后更新绘图:

 plot_params = reactiveValues(bins=5,title='This is the default title')


  output$distPlot <- renderPlot({
        hist(faithful[, 2],
             breaks = plot_params$bins,
             main = plot_params$title,
             col = 'darkgray',
             border = 'white')
  })

  observeEvent(setup$modalApply,{
    plot_params$bins = setup$bins
    plot_params$title = setup$plotTitle
  })
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