如何在 R Shiny 中将反应值设置为默认值？答案

【问题标题】：How to set reactive value to default in R Shiny?如何在 R Shiny 中将反应值设置为默认值？
【发布时间】：2020-06-24 06:06:51
【问题描述】：

我在更新闪亮的反应值时遇到问题。

所以我的应用程序基本上所做的就是保存来自用户的 textInputs。当用户决定上传所有文本输入时，我想重置 textInputs。

以下示例代码：

ui.R

ui <- fluidPage(
  sidebarPanel(
    textInput("words", "Please enter a word"), 

    actionButton("submit_new_word", "Save"), # this submits each single word
    textOutput("submitted_new_words"), # this show all submitted words

    actionButton("submit_upload", "Upload my Results") # this uploads all submitted words
  )
)

server.R

server <- function(input, output, session) {
  words_submitted <- paste("") # initial value 

  w_submitted <- eventReactive(input$submit_new_word, {
    words_submitted <- paste(words_submitted, " ", input$words)
    words_submitted <<- words_submitted

    updateTextInput(session, 
                    inputId = "words",
                    value = "") 

    return(words_submitted)
  }, ignoreNULL=FALSE)

  output$submitted_new_words <- renderText({
    w_submitted()
  })

  observeEvent(input$submit_upload, {
    # saveData(data_final) # upload, not needed for example here

    words_submitted <<- paste("")
  })
}

如果您尝试这个最小的示例，您会看到文本输入将被重置，但只有在之后再次点击“保存”按钮。

但是，我希望在单击“submit_upload”按钮时重置文本输入。

有人有想法吗？

【问题讨论】：

标签： r shiny shiny-reactivity

【解决方案1】：

您可能最好使用某种reactive。闪亮的工作方式是，如果没有附加反应性，它不会使客户端上的任何内容失效（刷新），例如renderText

library(shiny)

ui <- fluidPage(
        sidebarPanel(
                textInput("words", "Please enter a word"), 

                actionButton("submit_new_word", "Save"), # this submits each single word
                textOutput("submitted_new_words"), # this show all submitted words

                actionButton("submit_upload", "Upload my Results") # this uploads all submitted words
        )
)

v <- reactiveValues()

server <- function(input, output, session) {
        v$words_submitted <- paste("") # initial value 

        observeEvent(input$submit_new_word, {
                v$words_submitted <- paste(v$words_submitted, " ", input$words)
                updateTextInput(session, inputId = "words",value = "") 
        }, ignoreNULL=FALSE)

        output$submitted_new_words <- renderText({
                v$words_submitted
        })

        observeEvent(input$submit_upload, {
                # saveData(data_final) # upload, not needed for example here
                v$words_submitted <- paste("")
        })
}

# Run the application 
shinyApp(ui = ui, server = server)

【讨论】：