我想问一下，是否有办法在文件最终下载到我 Shiny 的应用程序之前显示加载消息。我的原始数据集很大，我想这就是延迟的原因。下面我附上一个玩具示例，以防有人可以对此应用重新使用的解决方案。
#ui.r
ui <- fluidPage(
# App title ----
titlePanel("Downloading Data"),
# Sidebar layout with input and output definitions ----
sidebarLayout(
# Sidebar panel for inputs ----
sidebarPanel(
# Input: Choose dataset ----
selectInput("dataset", "Choose a dataset:",
choices = c("rock", "pressure", "cars")),
# Button
downloadButton("downloadData", "Download")
),
# Main panel for displaying outputs ----
mainPanel(
tableOutput("table")
)
)
)
#server.r
server <- function(input, output) {
# Reactive value for selected dataset ----
datasetInput <- reactive({
switch(input$dataset,
"rock" = rock,
"pressure" = pressure,
"cars" = cars)
})
# Table of selected dataset ----
output$table <- renderTable({
datasetInput()
})
# Downloadable csv of selected dataset ----
output$downloadData <- downloadHandler(
filename = function() {
paste(input$dataset, ".csv", sep = "")
},
content = function(file) {
write.csv(datasetInput(), file, row.names = FALSE)
}
)
}
最佳答案
我已经根据您的代码实现了一个解决方案。您需要做的是在 downloadhandler() 中添加一个进度条.
library(shiny)
ui <- fluidPage(
# App title ----
titlePanel("Downloading Data"),
# Sidebar layout with input and output definitions ----
sidebarLayout(
# Sidebar panel for inputs ----
sidebarPanel(
# Input: Choose dataset ----
selectInput("dataset", "Choose a dataset:",
choices = c("rock", "pressure", "cars")),
# Button
downloadButton("downloadData", "Download")
),
# Main panel for displaying outputs ----
mainPanel(
tableOutput("table")
)
)
)
#server.r
server <- function(input, output) {
# Reactive value for selected dataset ----
datasetInput <- reactive({
switch(input$dataset,
"rock" = rock,
"pressure" = pressure,
"cars" = cars)
})
# Table of selected dataset ----
output$table <- renderTable({
datasetInput()
})
# Downloadable csv of selected dataset ----
output$downloadData <- downloadHandler(
filename = function() {
paste(input$dataset, ".csv", sep = "")
},
content = function(file) {
shiny::withProgress(
message = paste0("Downloading", input$dataset, " Data"),
value = 0,
{
shiny::incProgress(1/10)
Sys.sleep(1)
shiny::incProgress(5/10)
write.csv(datasetInput(), file, row.names = FALSE)
}
)
}
)
}
shiny::shinyApp(ui = ui, server = server)
您可以根据您的要求定制此解决方案(自定义消息、添加循环等)。我希望这有帮助 :-)
关于r - 为慢速下载处理程序()加载消息，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/54277922/