R 控制系统中更新的顺序

这里是一个MWE：

library(shiny)

runApp(shinyApp(
ui = pageWithSidebar(

  fluidRow(
    column(3, wellPanel(

    numericInput("numFields", "Select number of fields", 2, min = 1),
    br(),
    uiOutput("fields"),
    br(),
    actionButton("goButton", "Go!")

    )),

    column(3, wellPanel(      
      uiOutput("morefields")      
    )),

    column(3, wellPanel(

      numericInput("numFields2", "Select number of fields 2", 2, min = 1),
      br(),
      actionButton("goButton2", "Go2!")      

    ))    
  ),

server = function(input, output, session){

  output$fields <- renderUI({
    numFields <- as.integer(input$numFields)
    lapply(1:numFields, function(i) {
      textInput(paste0("field", i), paste0("Type in field ", i))
    })
  })

  output$morefields <- renderUI({

    if (input$goButton == 0) return(NULL)

    isolate({
      numFields <- as.integer(input$numFields)
      lapply(1:numFields, function(i) {
        checkboxInput(paste0("checkbox", i), paste0("Checkbox for field ",
                                                input[[paste0("field", i)]]))
      })
    })
  })

  observeEvent(input$goButton2, {
    numFields2 <- as.integer(input$numFields2)
    last_field <- paste0("field", numFields2)
    updateNumericInput(session, "numFields", value = numFields2)
    updateTextInput(session, "field1", value = "This is the first field")
    updateTextInput(session, last_field, value = "This is the last field")
  })

}))

现在生成了第二个UI，但字段仍然为空。我必须点击Go2！在所有UI完全更新之前，执行三次

我还尝试在服务器部件中执行以下操作：

同样，事件的过程看起来有点不同，但仍然需要点击三次才能得到我想要的

---

关于如何通过点击Go2获得最终结果的任何建议！按钮只按下一次？

我能够扩展您的想法并使其生效，尽管我必须承认这不是最漂亮的解决方案。第一个问题是，在调用更新文本字段的值之前，您需要确保文本字段已生成，因此我添加了一个

    isolate(
      if (vals$update == 1) {
        vals$update <- 2
      }
    )

希望这有帮助

  observeEvent(input$goButton2, {
    numFields2 <- as.integer(input$numFields2)
    updateNumericInput(session, "numFields", value = numFields2)
  }, priority = 2)

  observeEvent(vals$update, {
    numFields2 <- as.integer(input$numFields2)
    last_field <- paste0("field", numFields2)
    updateTextInput(session, "field1", value = "This is the first field")
    updateTextInput(session, last_field, value = "This is the last field")
  }, priority = 1)

  observeEvent(input$goButton2, {
    js$click("goButton")
  }, priority = 0)

    isolate(
      if (vals$update == 1) {
        vals$update <- 2
      }
    )

library(shiny)
library(shinyjs)
jscode <- "shinyjs.click = function(id) { setTimeout(function(){ $('#' + id).click(); }, 50); }"

runApp(shinyApp(
  ui = fluidPage(
    useShinyjs(),
    extendShinyjs(text = jscode),

    fluidRow(
      column(3, wellPanel(

        numericInput("numFields", "Select number of fields", 2, min = 1),
        br(),
        uiOutput("fields"),
        br(),
        actionButton("goButton", "Go!")

      )),

      column(3, wellPanel(      
        uiOutput("morefields")      
      )),

      column(3, wellPanel(

        numericInput("numFields2", "Select number of fields 2", 2, min = 1),
        br(),
        actionButton("goButton2", "Go2!")      

      ))    
    )),

    server = function(input, output, session){
      vals <- reactiveValues(update = 0)

      output$fields <- renderUI({
        isolate(
          if (vals$update == 1) {
            vals$update <- 2
          }
        )
        numFields <- as.integer(input$numFields)
        lapply(1:numFields, function(i) {
          textInput(paste0("field", i), paste0("Type in field ", i))
        })
      })

      output$morefields <- renderUI({

        if (input$goButton == 0) return(NULL)

        isolate({
          numFields <- as.integer(input$numFields)
          lapply(1:numFields, function(i) {
            checkboxInput(paste0("checkbox", i), paste0("Checkbox for field ",
                                                        input[[paste0("field", i)]]))
          })
        })
      })

      observeEvent(input$goButton2, {
        numFields2 <- as.integer(input$numFields2)
        vals$update <- 1
        updateNumericInput(session, "numFields", value = numFields2)
      })

      observeEvent(vals$update, {
        if (vals$update != 2) return(NULL)

        numFields2 <- as.integer(input$numFields2)
        last_field <- paste0("field", numFields2)
        updateTextInput(session, "field1", value = "This is the first field")
        updateTextInput(session, last_field, value = "This is the last field")

        vals$update <- 3
      })

      observeEvent(vals$update, {
        if (vals$update != 3) return(NULL)    
        js$click("goButton")
        vals$update <- 0
      })

    })
)