问题
Background: In my app, I have built a pop-up modal wherein users can define variables/parameters and they're subsequently stored in a reactiveValues() once an actionButton is pressed. This appears to work fine.
The problem: I have a separate actionButton which is supposed to clear/empty the reactiveValues that holds the inputs above. Unfortunately, this doesn't seem to work--that is, pressing the button doesn't do anything.
Minimally-reproducible code:
library(DT)
# UI modules
sidebarCharts <- function(id) {
ns <- NS(id)
tagList(
p(),
actionButton(ns("settings"), "Settings", icon = icon("cogs"), width = '100%', class = "btn btn-info"),p(),
actionButton(ns("refreshMainChart") ,"Refresh", icon("refresh"), width = '100%', class = "btn btn-primary"),p()
,textOutput(ns("info")) # FOR DEBUGGING
)
}
mainChartUI <- function(id) {
ns <- NS(id)
plotOutput(ns("mainChart"), width = "100%")
}
# UI module for the 2 buttons in the modal:
modalFooterUI <- function(ns) {
tagList(
modalButton("Cancel", icon("remove")),
actionButton(ns("modalApply"), "Apply", icon = icon("check"))
)
}
# module server
modal <- function(input, output, session) {
# Init reactiveValues() to store default values and updated values; https://github.com/rstudio/shiny/issues/1588
rv <- reactiveValues(clicks = 0, applyClicks = 0,
bins = 20,
bandwidth = 1)
reactiveBlotter <- reactiveValues() # Empty reactiveValues()
# DEBUGGING
output$info <- renderText({
paste("You clicked the 'Settings' button", rv$clicks, "times. You clicked the 'Apply' button", rv$applyClicks, "times. The bin size is currently set to", rv$bins, "and the bandwidth is currently set to", rv$bandwidth)
})
settngsModal <- function(ns) {
modalDialog(
withTags({ # UI elements for the modal go in here
fluidPage(
# titlePanel("Modal title optional"),
sidebarLayout(
sidebarPanel(
selectInput(ns("n_breaks"), label = "Number of bins:", choices = c(10, 20, 35, 50), selected = rv$bins, width = '100%'),
sliderInput(ns("bw_adjust"), label = "Bandwidth adjustment:", min = 0.2, max = 2, value = rv$bandwidth, step = 0.2, width = '100%'),
textInput(ns("testInputName"), label = "Name", width = '100%'),
selectInput(ns("testInput"), label = "Test Input", choices = c('A','B','C'), width = '100%'),
selectInput(ns("testInput2"), label = "Test Input 2", choices = c('D','E','F'), width = '100%'),
actionButton(ns("addToRV"), label = 'Add to reactiveValues'),p(),
actionButton(ns("clearRV"), label = 'Clear reactiveValues')
),
mainPanel(
# "Blotter table goes here.",
fluidRow(
DT::DTOutput(ns("blotterDT"))
)
)
)
)
}),
title = "Settings",
footer = modalFooterUI(ns),
size = "l",
easyClose = FALSE,
fade = TRUE)
}
# Sidebar 'Settings' modal
observeEvent(input$settings, {
showModal(settngsModal(session$ns)) # This opens the modal; settngsModal() defined below
rv$clicks <- rv$clicks + 1 # FOR DEBUGGING
})
observeEvent(input$modalApply, {
rv$applyClicks <- rv$applyClicks + 1 # FOR DEBUGGING
rv$bins <- input$n_breaks # This is where I set the reactiveValues() to those inputted into the modal.
rv$bandwidth <- input$bw_adjust
removeModal() # This should dismiss the modal (but it doesn't seem to work)
})
observeEvent(input$addToRV, {
req(input$testInputName, input$testInput, input$testInput2)
reactiveBlotter[[input$testInputName]] <- list(testInputName = input$testInputName, testInput = input$testInput, testInput2 = input$testInput2)
})
observeEvent(input$clearRV, {
reactiveBlotter <- reactiveValues() # This is the part that doesn't seem to work
})
blotterDf <- reactive({
do.call("rbind", lapply(reactiveBlotter, FUN = function(x) {
data.frame(name = x[["testInputName"]],
input1 = x[["testInput"]],
input2 = x[["testInput2"]])
}))
})
output$blotterDT <- DT::renderDT({
validate(need(length(names(reactiveBlotter)) > 0, "Add something to the blotter."))
DT::datatable(blotterDf(),
style = 'bootstrap',
class = 'table-bordered table-condensed',
rownames = TRUE,
options = list(dom = 't',
paging = F)
)
})
output$mainChart <- renderPlot({
input$refreshMainChart # Take dependency on the 'Refresh' buton
hist(faithful$eruptions, probability = TRUE, breaks = as.numeric(rv$bins),
xlab = "Duration (minutes)", main = "Geyser Eruption Duration")
dens <- density(faithful$eruptions, adjust = rv$bandwidth)
lines(dens, col = "blue")
})
}
# Define UI
ui <- fluidPage(
# Application title
titlePanel("stackoverflow example"),
sidebarLayout(
sidebarPanel(
sidebarCharts("main")
),
mainPanel(
mainChartUI("main")
)
)
)
# Server logic
server <- function(input, output) {
callModule(modal, "main")
}
# Complete app with UI and server components
shinyApp(ui, server)
What am I missing here? Any help is much appreciated!
回答1:
Alright folks, I figured this out after some extensive Google'ing. Here's what I determined:
- You can't "delete" or
NULL-ify an entirereactiveValues. Source: shiny: How to update a reactiveValues object? - The workaround is to create a single "dummy"
NULLlist within thereactiveValuesyou initialize and reactively update that (or set it toNULLto "delete"). Example: https://gist.github.com/aagarw30/4f10bad8aa94d47e024934350c16f2b8
So in my particular case, here's the updated code (which accomplishes what I want it to do, for now):
library(DT)
# UI modules
sidebarCharts <- function(id) {
ns <- NS(id)
tagList(
p(),
actionButton(ns("settings"), "Settings", icon = icon("cogs"), width = '100%', class = "btn btn-info"),p(),
actionButton(ns("refreshMainChart") ,"Refresh", icon("refresh"), width = '100%', class = "btn btn-primary"),p()
,textOutput(ns("info")) # FOR DEBUGGING
)
}
mainChartUI <- function(id) {
ns <- NS(id)
plotOutput(ns("mainChart"), width = "100%")
}
# UI module for the 2 buttons in the modal:
modalFooterUI <- function(ns) {
tagList(
modalButton("Cancel", icon("remove")),
actionButton(ns("modalApply"), "Apply", icon = icon("check"))
)
}
# module server
modal <- function(input, output, session) {
# Init reactiveValues() to store default values and updated values; https://github.com/rstudio/shiny/issues/1588
rv <- reactiveValues(clicks = 0, applyClicks = 0,
bins = 20,
bandwidth = 1)
reactiveBlotter <- reactiveValues(df = NULL) # Empty reactiveValues()
# DEBUGGING
output$info <- renderText({
paste("You clicked the 'Settings' button", rv$clicks, "times. You clicked the 'Apply' button", rv$applyClicks, "times. The bin size is currently set to", rv$bins, "and the bandwidth is currently set to", rv$bandwidth)
})
settngsModal <- function(ns) {
modalDialog(
withTags({ # UI elements for the modal go in here
fluidPage(
# titlePanel("Modal title optional"),
sidebarLayout(
sidebarPanel(
selectInput(ns("n_breaks"), label = "Number of bins:", choices = c(10, 20, 35, 50), selected = rv$bins, width = '100%'),
sliderInput(ns("bw_adjust"), label = "Bandwidth adjustment:", min = 0.2, max = 2, value = rv$bandwidth, step = 0.2, width = '100%'),
textInput(ns("testInputName"), label = "Name", width = '100%'),
selectInput(ns("testInput"), label = "Test Input", choices = c('A','B','C'), width = '100%'),
selectInput(ns("testInput2"), label = "Test Input 2", choices = c('D','E','F'), width = '100%'),
actionButton(ns("addToRV"), label = 'Add to reactiveValues'),p(),
actionButton(ns("clearRV"), label = 'Clear reactiveValues')
),
mainPanel(
# "Blotter table goes here.",
fluidRow(
DT::DTOutput(ns("blotterDT"))
)
)
)
)
}),
title = "Settings",
footer = modalFooterUI(ns),
size = "l",
easyClose = FALSE,
fade = TRUE)
}
# Sidebar 'Settings' modal
observeEvent(input$settings, {
showModal(settngsModal(session$ns)) # This opens the modal; settngsModal() defined below
rv$clicks <- rv$clicks + 1 # FOR DEBUGGING
})
observeEvent(input$modalApply, {
rv$applyClicks <- rv$applyClicks + 1 # FOR DEBUGGING
rv$bins <- input$n_breaks # This is where I set the reactiveValues() to those inputted into the modal.
rv$bandwidth <- input$bw_adjust
removeModal() # This should dismiss the modal (but it doesn't seem to work)
})
observeEvent(input$addToRV, {
req(input$testInputName, input$testInput, input$testInput2)
reactiveBlotter[["df"]][[input$testInputName]] <- list(testInputName = input$testInputName, testInput = input$testInput, testInput2 = input$testInput2)
})
observeEvent(input$clearRV, {
# reactiveBlotter <- reactiveValues() # This doesn't work
# lapply(X = names(reactiveBlotter), FUN = function(x) {
# reactiveBlotter[[x]] <- NULL
# }) # This is one way to do it, but the names of the items within the reactiveValues() still remain.
reactiveBlotter[["df"]] <- NULL
})
blotterDf <- reactive({
do.call("rbind", lapply(reactiveBlotter[["df"]], FUN = function(x) {
data.frame(name = x[["testInputName"]],
input1 = x[["testInput"]],
input2 = x[["testInput2"]])
}))
})
output$blotterDT <- DT::renderDT({
validate(need(length(names(reactiveBlotter[["df"]])) > 0, "Add something to the blotter."))
DT::datatable(blotterDf(),
style = 'bootstrap',
class = 'table-bordered table-condensed',
rownames = TRUE,
options = list(dom = 't',
paging = F)
)
})
output$mainChart <- renderPlot({
input$refreshMainChart # Take dependency on the 'Refresh' buton
hist(faithful$eruptions, probability = TRUE, breaks = as.numeric(rv$bins),
xlab = "Duration (minutes)", main = "Geyser Eruption Duration")
dens <- density(faithful$eruptions, adjust = rv$bandwidth)
lines(dens, col = "blue")
})
}
# Define UI
ui <- fluidPage(
# Application title
titlePanel("stackoverflow example"),
sidebarLayout(
sidebarPanel(
sidebarCharts("main")
),
mainPanel(
mainChartUI("main")
)
)
)
# Server logic
server <- function(input, output) {
callModule(modal, "main")
}
# Complete app with UI and server components
shinyApp(ui, server)
Note, I initialize the reactiveBlotter object with an entry for df = NULL and then reference this as reactiveBlotter[["df"]] throughout the rest of the code snippet and it works.
来源：https://stackoverflow.com/questions/52261240/shiny-how-to-initialize-empty-reactivevalues-with-an-actionbutton