R Shiny observeEvent continues to trigger - r

Question

I'm struggling to get an observeEvent process to run only once after it's triggering event - a button click. This illustrates:
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$input_value)
})
}
shinyApp(ui = ui, server = server, options = list(launch.browser = T))
You'll see that after the button has been clicked once, the textOutput becomes responsive to textInput changes rather than button clicks.
I've tried this approach:
server = function(input, output, session) {
o = observeEvent(input$execute, {
output$report = renderText(input$input_value)
o$destroy
})
}
No effect. I've also tried employing the isolate function with no luck. Grateful for suggestions.

Answer 1

You probably had your isolate() call wrapped around renderText() instead of input$input_value. This should do it for you:
require(shiny)
ui = fluidPage(
textInput("input_value", '1. input a value. 2. click button. 3. input another value', ''),
actionButton("execute", 'execute'),
textOutput('report')
)
server = function(input, output, session) {
observeEvent(input$execute, {
output$report = renderText(isolate(input$input_value))
})
}
shinyApp(ui = ui, server = server, options = list(launch.browser = T))

Answer 2

Alliteratively you can bring the reactive values into an isolated scope of observeEvent() as below:
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))