添加或删除输入后保留 UI 文本输入

Question

我正在构建一个小型 UI，用户将在其中输入 splitLayout 文本行，该文本行构建一个语句（此问题不需要）来解决难题。

但是，如果用户决定他/她需要附加行或更少行来解决难题，我想添加或删除新的输入行不要删除剩余的输入行。

*灰色是占位符。

我怎样才能最好地达到我想要的结果：

请在下面找到我的修剪代码。感谢您的意见。

library(shiny)

# Define UI
ui <- fluidPage(
  # Application title
  titlePanel("Identify A, B and C"),
  sidebarLayout(
    sidebarPanel(width = 5,
                 helpText("Present a statement and receive a response: 1 is a Knight who always tells the truth, 2 is a Knave who always lies, and 3 is a Normal who can do either."),
                 # Number of Questions
                 numericInput(inputId = "Questions", label = "Number of Questions", 
                              value = 1, min = 1, max = 10, step = 1),
                 splitLayout(cellWidths = c("25%","70%"), 
                             style = "border: 1px solid silver;",
                             cellArgs = list(style = "padding: 3px"),
                             uiOutput("textQuestions"), uiOutput("textQuestions2"))
    ),
    mainPanel(
      # Right hand side output
    )
  )
)

# Define server logic 
server <- function(input, output) {
  ####### I don't want these to delete initially everytime??
  output$textQuestions <- renderUI({
    Questions <- as.integer(input$Questions)
    lapply(1:Questions, function(i) {
      textInput(inputId = paste0("Who", i), label = paste0(i, ". Ask:"), placeholder = "A")
    })
  })
  ########
  output$textQuestions2 <- renderUI({
    Questions <- as.integer(input$Questions)
    lapply(1:Questions, function(i) {
      textInput(inputId = paste0("Q", i) , label = paste0("Logic:"), 
                value = "", placeholder = "A == 1 & (B != 2 | C == 3)")
    })
  })
  ######
}

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

Answer 1

看起来有人已经使用uiOutput+renderUI 给了你答案，所以我要走另一条路：使用insertUI 和removeUI。

我没有为“问题数量”提供数字输入，而是将其替换为“添加问题”按钮和“删除问题”按钮。我有一个变量来跟踪有多少问题。每次按下“添加问题”，我们都会添加一行。当按下“删除问题”时，我们删除最后一行。

代码如下：

library(shiny)

# Define UI
ui <- fluidPage(
  # Application title
  titlePanel("Identify A, B and C"),
  sidebarLayout(
    sidebarPanel(
      width = 5,
      helpText("Present a statement and receive a response: 1 is a Knight who always tells the truth, 2 is a Knave who always lies, and 3 is a Normal who can do either."),
      # Buttons to add/remove a question
      actionButton("add", "Add question"),
      actionButton("remove", "Remove question"),
      div(id = "questions",
          style = "border: 1px solid silver;")
    ),
    mainPanel(
      # Right hand side output
    )
  )
)

# Define server logic 
server <- function(input, output) {
  # Keep track of the number of questions
  values <- reactiveValues(num_questions = 0)

  # Add a question
  observeEvent(input$add, ignoreNULL = FALSE, {
    values$num_questions <- values$num_questions + 1
    num <- values$num_questions
    insertUI(
      selector = "#questions", where = "beforeEnd",
      splitLayout(
        cellWidths = c("25%","70%"), 
        cellArgs = list(style = "padding: 3px"),
        id = paste0("question", num),
        textInput(inputId = paste0("Who", num),
                  label = paste0(num, ". Ask:"),
                  placeholder = "A"),
        textInput(inputId = paste0("Q", num) ,
                  label = paste0("Logic:"),
                  placeholder = "A == 1 & (B != 2 | C == 3)")
      )
    )
  })

  # Remove a question
  observeEvent(input$remove, {
    num <- values$num_questions
    # Don't let the user remove the very first question
    if (num == 1) {
      return()
    }
    removeUI(selector = paste0("#question", num))
    values$num_questions <- values$num_questions - 1
  })


}

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

编辑

OP 请求一种根据问题编号检索用户输入的方法。为此：

1. 将以下内容添加到 UI

   numericInput("question_num", "Show question number", 1),
   textOutput("question")
   

2. 将以下内容添加到服务器

   get_question <- function(q) {
     paste(
       input[[paste0("Who", q)]],
       ":",
       input[[paste0("Q", q)]]
     )
   }
   
   output$question <- renderText({
     get_question(input$question_num)
   })
   

Answer 2

你可以将它存储在一个反应​​值中：

  global <- reactiveValues(ask = c(), logic = c())

  observe({
    Questions <- as.integer(input$Questions)
    lapply(1:Questions, function(i) {
      inputVal <- input[[paste0("Who", i)]]
      if(!is.null(inputVal)){
        global$logic[i] <- inputVal
      }
      inputValQ <- input[[paste0("Q", i)]]
      if(!is.null(inputValQ)){
        global$ask[i] <- inputValQ
      }
    })
  })

这将为您生成以下代码示例： 作为副作用，如果输入被删除然后重新获取，这些值也会被存储。

library(shiny)

# Define UI
ui <- fluidPage(
  # Application title
  titlePanel("Identify A, B and C"),
  sidebarLayout(
    sidebarPanel(width = 5,
                 helpText("Present a statement and receive a response: 1 is a Knight who always tells the truth, 2 is a Knave who always lies, and 3 is a Normal who can do either."),
                 # Number of Questions
                 numericInput(inputId = "Questions", label = "Number of Questions", 
                              value = 1, min = 1, max = 10, step = 1),
                 splitLayout(cellWidths = c("25%","70%"), 
                             style = "border: 1px solid silver;",
                             cellArgs = list(style = "padding: 3px"),
                             uiOutput("textQuestions"), uiOutput("textQuestions2"))
    ),
    mainPanel(
      # Right hand side output
    )
  )
)

# Define server logic 
server <- function(input, output) {
  global <- reactiveValues(ask = c(), logic = c())

  observe({
    Questions <- as.integer(input$Questions)
    lapply(1:Questions, function(i) {
      inputVal <- input[[paste0("Who", i)]]
      if(!is.null(inputVal)){
        global$ask[i] <- inputVal
      }
      inputValQ <- input[[paste0("Q", i)]]
      if(!is.null(inputValQ)){
        global$logic[i] <- inputValQ
      }
    })
  })
  ####### I don't want these to delete initially everytime??
  output$textQuestions <- renderUI({
    Questions <- as.integer(input$Questions)
    lapply(1:Questions, function(i) {
      textInput(inputId = paste0("Who", i), label = paste0(i, ". Ask:"), placeholder = "A", value = global$ask[i])
    })
  })
  ########
  output$textQuestions2 <- renderUI({
    Questions <- as.integer(input$Questions)
    lapply(1:Questions, function(i) {
      textInput(inputId = paste0("Q", i) , label = paste0("Logic:"), value = global$logic[i],
                placeholder = "A == 1 & (B != 2 | C == 3)")
    })
  })
  ######
}

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