即使条件没有改变，也可以在 Shiny 中触发 observeEvent

Question

由于observeEvent 的工作方式（通常非常直观），我在获取我正在寻找的应用程序中的功能时遇到了一些问题。

我正在寻找的基本功能是用户可以输入几个数字，单击“提交”，然后弹出一个模式以获取用户的姓名。之后，应用程序记录名称并对数字求和，然后清除输入。然后我希望用户能够使用相同的名称重复该过程 - 但应用程序当前的结构使得总和使用 observeEvent 仅在名称不同时响应（即，使用相同的名称两次一行不起作用，尽管我希望这样做）。您可以在应用程序中看到我的解决方案尝试是重置inputSweetAlert 的输入（使用shinyjs），但我认为它无法访问它，因为它实际上不在 UI 端。我正在使用 shinyWidgets sweetAlerts，我想继续这样做。

这是一个示例应用：

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

ui <- fluidPage(
  shinyjs::useShinyjs(),
  numericInput("num1", "Enter a number", value=NULL),
  numericInput("num2", "Enter another number", value=NULL),
  actionButton(inputId = "go", label = "submit"),
  verbatimTextOutput(outputId = "res1"),
  verbatimTextOutput(outputId = "res2")
)

server <- function(input, output, session) {

  observeEvent(input$go, {
    inputSweetAlert(session = session, inputId = "name", title = "What's your name?")
  })

  x <- reactiveValues(val=NULL)

  observeEvent(input$name, {
    x$val <- input$num1 + input$num2
    confirmSweetAlert(session = session, inputId = "confirmed", title = "Success!", text = "Your responses have been recorded. All is in order.", type = "success", btn_labels = c("Ok, let me continue")
    )
  })

  ## A possible approach to a solution...
  observeEvent(input$confirmed, {
    shinyjs::reset("num1") 
    shinyjs::reset("num2") 
    shinyjs::reset("name")
  })

  output$res1 <- renderPrint(paste("Name:", input$name))
  output$res2 <- renderPrint(paste("Sum:", x$val))
}

shinyApp(ui = ui, server = server)

感谢您提供的任何帮助！

Answer 1

你可以通过JS重置input$name：

runjs('Shiny.setInputValue("name", null, {priority: "event"});')

这是一个工作示例：

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

ui <- fluidPage(
  shinyjs::useShinyjs(),
  numericInput("num1", "Enter a number", value = NULL),
  numericInput("num2", "Enter another number", value = NULL),
  actionButton(inputId = "go", label = "submit"),
  verbatimTextOutput(outputId = "res1"),
  verbatimTextOutput(outputId = "res2")
)

server <- function(input, output, session) {

  observeEvent(input$go, {
    inputSweetAlert(session = session, inputId = "name", title = "What's your name?")
    runjs('Shiny.setInputValue("name", null, {priority: "event"});')
  })

  x <- reactiveValues(val = NULL)

  observeEvent(input$name, {
    x$val <- input$num1 + input$num2
    confirmSweetAlert(session = session, inputId = "confirmed", title = "Success!", text = "Your responses have been recorded. All is in order.", type = "success", btn_labels = c("Ok, let me continue"))
  })

  observeEvent(input$confirmed, {
    shinyjs::reset("num1") 
    shinyjs::reset("num2") 
    shinyjs::reset("mytext")
  })

  output$res1 <- renderPrint(paste("Name:", input$name))
  output$res2 <- renderPrint(paste("Sum:", x$val))
}

shinyApp(ui = ui, server = server)

更多信息请查看article。

Answer 2

这是一种解决方法。这个想法在于在每次点击按钮时更改输入 ID。

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

ui <- fluidPage(
  shinyjs::useShinyjs(),
  numericInput("num1", "Enter a number", value=NULL),
  numericInput("num2", "Enter another number", value=NULL),
  actionButton(inputId = "go", label = "submit"),
  verbatimTextOutput(outputId = "res1"),
  verbatimTextOutput(outputId = "res2")
)

server <- function(input, output, session) {

  go <- reactive({
    input$go
  })

  observeEvent(input$go, {
    inputSweetAlert(session = session, inputId = sprintf("name-%d", go()), 
                    title = "What's your name?")
  })

  x <- reactiveValues(val=NULL)

  observeEvent(input[[sprintf("name-%d", go())]], {
    x$val <- input$num1 + input$num2
    confirmSweetAlert(session = session, inputId = "confirmed", title = "Success!", text = "Your responses have been recorded. All is in order.", type = "success", btn_labels = c("Ok, let me continue")
    )
  })

  ## A possible approach to a solution...
  observeEvent(input$confirmed, {
    shinyjs::reset("num1") 
    shinyjs::reset("num2") 
    shinyjs::reset("mytext")
  })

  output$res1 <- renderPrint(paste("Name:", input[[sprintf("name-%d", go())]]))
  output$res2 <- renderPrint(paste("Sum:", x$val))
}

shinyApp(ui = ui, server = server)