无法获得 flexdashboard 模态 Shiny 反应性来处理 NULL 状态

Question

首先，这是一个最小的可重现示例：

假设我有以下 flexdashboard 应用 example.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')
    })

  })
}

这是我想要完成的：

当页面加载时使用默认参数呈现 distPlot。这应该总是发生。
当我单击 'Settings' actionButton 时，它会弹出模态叠加层（但会在背景中保持原始状态的绘图）
允许用户更改弹出模式中的参数，但在用户点击 'Apply' 按钮之前不要重新渲染绘图。

我想我已经弄明白了#1，但是当我点击 'Settings' 按钮时，我得到了一个错误 Invalid breakpoints produced by 'breaks(x)': NULL。然后，我更改了输入，但它什么也没做（除非我再次点击设置 actionButton（这反过来用给定的输入渲染图）。

我做错了什么？

谢谢！！

Answer 1

可能存在时间问题。当您按下设置按钮时，setup$settings 变为 1，因此 renderPlot 会尝试重新绘制。如果在设置滑块之前发生这种情况，setup$bins 是 NULL 并且您会收到错误消息。

您可以在 renderPlot 的第一个 if 中添加一个条件，以便仅当用户按下模态中的“应用”按钮时才使用 setup$bins 绘制：

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')
    })

!isTruthy 将是 TRUE 如果 setup$modalApply 是 NULL（模态还没有被创建）或者如果它是 0（用户没有尚未按下按钮）。一旦用户按下“应用”按钮，绘图就会更新。

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。它可以在用户单击应用按钮时更新，这又会更新绘图：

 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
  })

无法获得 flexdashboard 模态 Shiny 反应性来处理 NULL 状态

Can't get flexdashboard modal Shiny reactivity to deal with NULL state

r

shiny

shinydashboard

flexdashboard