根据 Shiny 应用程序中模块的输入禁用 UI 中的按钮

Question

在一个闪亮的应用程序中，我试图根据用户来自模块的输入来禁用/启用主应用程序 UI 中的操作按钮。基本上，我希望禁用“下一页”（submit）按钮，直到用户响应最后一项（item3）。当用户响应最后一项时，我希望启用该按钮。但是，我的应用没有更新操作按钮的切换状态。

这是一个使用{Golem} 结构的最小可重现示例：

app_ui.R:

library("shiny")
library("shinyjs")

app_ui <- function(request) {
  tagList(
    useShinyjs(),
    fluidPage(
      mod_mod1_ui("mod1_ui_1"),
      actionButton(inputId = "submit",
                   label = "Next Page")
    )
  )
}

app_server.R:

library("shiny")
library("shinyjs")

app_server <- function( input, output, session ) {
  state <- mod_mod1_server("mod1_ui_1")
  
  # Enable the "Next Page" button when the user responds to the last item
  observe({
    toggleState("submit", state == TRUE)
    })  
}

mod_mod1.R:

library("shiny")
library("shinyjs")

mod_mod1_ui <- function(id){
  ns <- NS(id)
  tagList(
    radioButtons(inputId = ns("item1"),
                 label = "Item 1",
                 choices = c(1, 2, 3, 4),
                 selected = character(0)),
    
    radioButtons(inputId = ns("item2"),
                 label = "Item 2",
                 choices = c(1, 2, 3, 4),
                 selected = character(0)),
    
    radioButtons(inputId = ns("item3"),
                 label = "Item 3",
                 choices = c(1, 2, 3, 4),
                 selected = character(0))
  )
}

mod_mod1_server <- function(id){
  moduleServer( id, function(input, output, session){
    ns <- session$ns
    
    # When the user completes the last survey question
    completed <- logical(1)
    
    observe({
      lastQuestion <- input$item3
      if(!is.null(lastQuestion)){
        completed <- TRUE
      } else {
        completed <- FALSE
      }
      browser()
    })
    
    return(completed)
 
  })
}

使用browser() 语句，completed 变量似乎已在模块中正确更新，但 state 变量未在主应用程序中更新。

Answer 1

我不清楚当用户仅响应 item3 或所有项目（1 到 3）时，您是否希望它起作用。我假设是后者。但是，您可以根据用例的需要进行修改。定义 reactiveValues 对象有效。试试这个

library("shiny")
library("js")

mod_mod1_ui <- function(id){
  ns <- NS(id)
  tagList(
    radioButtons(inputId = ns("item1"),
                 label = "Item 1",
                 choices = c(1, 2, 3, 4),
                 selected = character(0)),
    
    radioButtons(inputId = ns("item2"),
                 label = "Item 2",
                 choices = c(1, 2, 3, 4),
                 selected = character(0)),
    
    radioButtons(inputId = ns("item3"),
                 label = "Item 3",
                 choices = c(1, 2, 3, 4),
                 selected = character(0))
  )
}

mod_mod1_server <- function(id){
  moduleServer( id, function(input, output, session){
    ns <- session$ns
    
    # When the last survey question is completed
    rv <- reactiveValues(completed=1)
    
    observe({
      lastQuestion <- input$item3
      if(!is.null(lastQuestion) & !is.null(input$item2) & !is.null(input$item1)){
        rv$completed <- 1
      } else {
        rv$completed <- 0
      }
      print(rv$completed )
      #browser()
      
    })
    
    return(rv)
  })
}

app_ui <- function(request) {
  fluidPage(
    useShinyjs(),
    tagList(
      mod_mod1_ui("mod1_ui_1"),
      actionButton(inputId = "submit",
                   label = "Next Page") 
    )
  )
}

app_server <- function( input, output, session ) {
  state <- mod_mod1_server("mod1_ui_1")
  
  # Don't show "Next Page" button until last item is completed
  observe({
    toggleState("submit", state$completed == TRUE)
  })
 
}

shinyApp(ui = app_ui, server = app_server)