更改输入值时不要清除（用户输入的）反应变量的值

Question

我想使用附加的演示代码收集个人信息（姓名和年龄）作为用户输入。初始个体数为1，当用户increases/decreases个体数的值时，会反应add/reduce对应行收集个体信息。我的问题是如何避免在increasing/decreasing个人的数量时抹掉当前输入的信息。例如截图1显示的是用户（我）输入的个人1的信息。当我将个人数量的值更改为2时，我之前输入的信息被抹掉了（截图2），我不得不重新输入个人1的信息。什么我希望当我将个人数量增加到 2 时，会像 屏幕截图 3（个人 1 的信息不会被删除）。任何人都可以帮我解决这个问题吗？谢谢！

更新于 2022 年 5 月 15 日

使用 isolate 的更新答案正是我要找的。再次感谢@jpdugo17 的帮助。

示例代码

library(shiny)
ui <- fluidPage(
  tabsetPanel(
    tabPanel(
      h4("Individual Information"),
      fluidRow(column(4,numericInput("ninds",
                                     label = "Number of individuals",
                                     value = 1, min = 1, step = 0.5, width = "300px"))),
      br(),
      fluidRow(column(2,align = "center",strong("Individual #")),
               column(5,align = "center",strong("Individual Name")),
               column(5,align = "center",strong("Age"))),
      fluidRow(
        column(2,wellPanel(uiOutput("indNum"))),
        column(5,wellPanel(uiOutput("Name"))),
        column(5,wellPanel(uiOutput("Age"))))
    )
  )
)

server <- function(input, output) {
  # create reactive variable paste0("individualNum", i) for further using
  output$indNum <- renderUI({
    num <- as.integer(input$ninds)
    req(num)
    lapply(1:num, function(i) {
      numericInput(paste0("individualNum", i), value = i, label = "", max = i, min = i)
    })
  })
  # create reactive variable paste0("name", i) for further using 
  output$Name <- renderUI({
    num <- as.integer(input$ninds)
    req(num)
    lapply(1:num, function(i) {
      textInput(paste0("name", i), label = "")
    })
  })
  # create reactie variable paste0("age", i) for further using 
  output$Age <- renderUI({
    num <- as.integer(input$ninds)
    req(num)
    lapply(1:num, function(i) {
      numericInput(paste0("age", i), label = "", value = 0)
    })
  })
}

# Run the app ----
shinyApp(ui, server)

截图-1 截图2 截图3

Answer 1

编辑:

我们可以将 isolate 与输入的当前值一起使用，并将其作为 numericInput 或 textInput 中的值参数传递。这将起作用，因为任何尚不存在的输入都会产生 NULL.

server <- function(input, output) {
  # create reactive variable paste0("individualNum", i) for further using

  num <- reactive({
    req(input$ninds)
    input$ninds
  })

  output$indNum <- renderUI({
    lapply(1:num(), function(i) {
      numericInput(paste0("individualNum", i), value = i, label = "", max = i, min = i)
    })
  })
  # create reactive variable paste0("name", i) for further using
  output$Name <- renderUI({
    lapply(1:num(), function(i) {
      textInput(paste0("name", i), label = "", value = isolate(input[[paste0("name", i)]]))
    })
  })
  # create reactie variable paste0("age", i) for further using
  output$Age <- renderUI({
    lapply(1:num(), function(i) {
      numericInput(paste0("age", i), label = "", value = isolate(input[[paste0("age", i)]]))
    })
  })
}

原始答案使用 insertUI:

我们可以实现这样的逻辑：创建一个计数器来存储当前输入的数字，制作两个按钮，一个用于添加，另一个用于删除输入。我们必须用具有唯一 ID 的 div 包装每个输入（因为输入函数通常会添加多个元素）。

library(shiny)
library(purrr)

ui <- fluidPage(
  tabsetPanel(
    tabPanel(
      h4("Individual Information"),
      fluidRow(
        column(
          4, fluidRow(
            column(6, numericInput("ninds",
              label = "Number of individuals",
              value = 1, min = 1, step = 0.5, width = "300px"
            )), column(3, actionButton("add_ui", "Add Individual", style = "background-color: green;")),
            column(3, actionButton("remove_ui", "Remove Individual", style = "background-color: red;"))
          )
        )
      ),
      br(),
      fluidRow(
        column(2, align = "center", strong("Individual #")),
        column(5, align = "center", strong("Individual Name")),
        column(5, align = "center", strong("Age"))
      ),
      fluidRow(
        column(2, wellPanel(id = "IndNumber")),
        column(5, wellPanel(id = "Name")),
        column(5, wellPanel(id = "Age"))
      )
    )
  )
)


server <- function(input, output) {

  # track the number of inputs
  ui_counter <- reactiveVal(1)

  observeEvent(input$add_ui, {
    div_nms <- map_chr(c("individualNum", "name", "age"), ~ paste0("div", .x, ui_counter()))

    # individual number
    insertUI(
      selector = "#IndNumber",
      ui = div(
        id = div_nms[[1]],
        numericInput(paste0("individualNum", ui_counter()),
          label = "",
          value = ui_counter(),
          min   = ui_counter(),
          max   = ui_counter()
        )
      )
    )

    # name input
    insertUI(
      selector = "#Name",
      ui = div(id = div_nms[[2]], textInput(paste0("name", ui_counter()),
        label = ""
      ))
    )

    # age input
    insertUI(
      selector = "#Age",
      ui = div(id = div_nms[[3]], numericInput(paste0("age", ui_counter()),
        label = "",
        value = 0
      ))
    )


    ui_counter(ui_counter() + 1)
  })

  # observer to remove the divs containing the inputs
  observeEvent(input$remove_ui, {
    if (ui_counter() > 1) {
      walk(c("individualNum", "name", "age"), ~ removeUI(paste0("#div", .x, ui_counter() - 1)))
      ui_counter(ui_counter() - 1)
    }
  })
}

# Run the app ----
shinyApp(ui, server)

更改输入值时不要清除（用户输入的）反应变量的值

Do not wipe out (user entered) values of reactive variables when changing input values

r

shiny

shiny-reactivity