r - 如何将 observeEvent 与复选框事件一起使用 Shiny

Question

如何基于 TRUE/FALSE 复选框事件使用 observeEvent 触发操作(在本例中为 updateSelectInput)？

例如我想在测试为真时更新结果:

library(shiny)
ui<-fluidPage(
  checkboxInput("test","Test",value=FALSE),
  selectInput("result","Result",choices=c("1","2","3"),selected="1")
)

server<-function(input, output){
  observeEvent(input$test{
    updateSelectInput(session,"result",choices=c("1","2","3","4","5"),selected="1")
  })
}


shinyApp(ui=ui,server=server)

Answer 1

见下文:

library(shiny)
ui<-fluidPage(
    checkboxInput("test","Test",value=FALSE),
    selectInput("result","Result",choices=c("1","2","3"),selected="1")
)

server<-function(input, output, session){
    observeEvent(input$test,{
        updateSelectInput(session,"result",choices=c("1","2","3","4","5"),selected="1")
    }, ignoreInit = TRUE)
}


shinyApp(ui=ui,server=server)

我在服务器 function() 中添加了 session，在 input$test 之后添加了一个逗号，并且 ignoreInit = TRUE.

更新

library(shiny)
ui<-fluidPage(
    checkboxInput("test","Test",value=FALSE),
    selectInput("result","Result",choices=c("1","2","3"),selected="1")
)

server<-function(input, output, session){
    observeEvent(input$test,{
        updateSelectInput(session,"result",choices=if(input$test == FALSE){c("1","2","3")}else{c("1","2","3","4","5")},selected="1")

    }, ignoreInit = TRUE)
}


shinyApp(ui=ui,server=server)