[英]R Shiny observeEvent continues to trigger
I'm struggling to get an observeEvent process to run only once after it's triggering event - a button click.我正在努力让observeEvent 进程在触发事件后只运行一次 - 单击按钮。 This illustrates:
这说明:
require(shiny)
ui = fluidPage(
textInput("input_value", '1. input a value. 2. click button. 3. input another value', ''),
actionButton("execute", 'execute'),
textOutput('report')
)
server = function(input, output, session) {
observeEvent(input$execute, {
output$report = renderText(input$input_value)
})
}
shinyApp(ui = ui, server = server, options = list(launch.browser = T))
You'll see that after the button has been clicked once, the textOutput becomes responsive to textInput changes rather than button clicks.您将看到,在单击按钮一次后,textOutput 将响应 textInput 更改而不是按钮单击。
I've tried this approach:我试过这种方法:
server = function(input, output, session) {
o = observeEvent(input$execute, {
output$report = renderText(input$input_value)
o$destroy
})
}
No effect.没有效果。 I've also tried employing the
isolate
function with no luck.我也尝试过使用
isolate
功能,但没有运气。 Grateful for suggestions.感谢您的建议。
You probably had your isolate()
call wrapped around renderText()
instead of input$input_value
.您可能在
renderText()
而不是input$input_value
周围使用了isolate()
调用。 This should do it for you:这应该为你做:
require(shiny)
ui = fluidPage(
textInput("input_value", '1. input a value. 2. click button. 3. input another value', ''),
actionButton("execute", 'execute'),
textOutput('report')
)
server = function(input, output, session) {
observeEvent(input$execute, {
output$report = renderText(isolate(input$input_value))
})
}
shinyApp(ui = ui, server = server, options = list(launch.browser = T))
Alliteratively you can bring the reactive values into an isolated scope of observeEvent()
as below:您可以将反应值带入
observeEvent()
的隔离范围,如下所示:
library(shiny)
ui = fluidPage(
textInput("input_value", '1. input a value. 2. click button. 3. input another value', ''),
actionButton("execute", 'execute'),
textOutput('report')
)
server = function(input, output, session) {
observeEvent(input$execute, {
# bringing reactive values into an isolated scope
inp_val <- input$input_value
output$report <- renderText(inp_val)
})
}
shinyApp(ui = ui, server = server, options = list(launch.browser = T))
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