Shiny：根据索引动态添加/删除 textInput 行

Question

基于this article我改变了我的脚本：

library(shiny)

ui = fluidPage( 
  actionButton("add", "Add new Row", icon=icon("plus", class=NULL, lib="font-awesome")),
  actionButton("remove", "Remove last Row", icon=icon("times", class = NULL, lib = "font-awesome")),
  tags$div(id = 'placeholder')
)

server = function(input, output) {

  ## keep track of elements inserted and not yet removed
  inserted <- c()

  observeEvent(input$add, {
    id <- ''
    insertUI(
      selector = "#placeholder",
      where = "beforeBegin",
      ui =tags$div(
        id = id,
        fluidRow(
          column(2,
                 textInput("alias", label = h5("first"))
          ),
          column(2,
                 textInput("pop", label = h5("second"))
          ),
          column(2,
                 textInput("parent", label = h5("third"))
          ),
          column(2,
                 textInput("dims", label = h5("fifth"))
          ),
          column(2,
                 textInput("method", label = h5("fourth"))
          ),
          column(2,
                 textInput("args", label = h5("sixth"))
          )
        ) 
      )
    )

    inserted <<- c(inserted, id)

  })

  observeEvent(input$remove, {
    removeUI(
      ## pass in appropriate div id
      selector = paste0('#', inserted[length(inserted)])
    )

    inserted <<- inserted[-length(inserted)]
  })

}

shinyApp(ui = ui, server = server)

我查看了this question，但比以前更加困惑。add 按钮可以正常工作，但点击remove 按钮时行不会消失。我做错了什么？

谢谢！

Answer 1

除了 id 的分配，你已经很接近了。 你忘记设置id了吗？我看到的唯一任务是：id <- ''。 此外，您应该使用 reactiveValues() 而不是闪亮的全局变量。

请参阅下面的改编代码：

library(shiny)

ui = fluidPage( 
  actionButton("add", "Add new Row", icon=icon("plus", class=NULL, lib="font-awesome")),
  actionButton("remove", "Remove last Row", icon=icon("times", class = NULL, lib = "font-awesome")),
  tags$div(id = 'placeholder')
)

server = function(input, output) {

  ## keep track of elements inserted and not yet removed
  inserted <- reactiveValues(val = 0)

  observeEvent(input$add, {
    id <- length(inserted$val) + 1
    insertUI(
      selector = "#placeholder",
      where = "beforeBegin",
      ui =tags$div(
        id = id,
        fluidRow(
          column(2,
                 textInput("alias", label = h5("first"))
          ),
          column(2,
                 textInput("pop", label = h5("second"))
          ),
          column(2,
                 textInput("parent", label = h5("third"))
          ),
          column(2,
                 textInput("dims", label = h5("fifth"))
          ),
          column(2,
                 textInput("method", label = h5("fourth"))
          ),
          column(2,
                 textInput("args", label = h5("sixth"))
          )
        ) 
      )
    )
    inserted$val <- c(inserted$val, id)
    print(inserted$val)
  })

  observeEvent(input$remove,{
    print(inserted$val)
    removeUI(
      ## pass in appropriate div id
      selector = paste0('#', inserted$val[length(inserted$val)])
    )

    inserted$val <- inserted$val[-length(inserted$val)]
  })

}

shinyApp(ui = ui, server = server)