Accessing values inside eventReactive - shiny

Question

I need help with a basic Shiny question. My goal is to make a simple math quiz app (What is 4 x 4?). I want to create values with one button, select a numeric answer, and then press another answer button. My problem is that i cannot find a way to access the values that are stored inside eventReactive. I have simplified the problem in the code below. The goal of this app is to ask for a number, and then to supply it. Thank you in advance!
# Goal: Fetch a number, then input that number, then receive paste("correct")/paste("incorrect)
ui <- fluidPage(
textOutput(outputId = "out"),
numericInput(inputId = "inn",
label = "",
value = 0),
actionButton("answer", "Answer"),
actionButton("question", "New Question"),
)
server <- function(input, output) {
data <- eventReactive(input$question,{
a <- sample.int(10,1)
paste("Enter",a)
})
output$out <- renderText({data()})
}
shinyApp(ui,server)

Answer 1

Here is what I would do
ui <- fluidPage(
textOutput(outputId = "out"),
numericInput(inputId = "inn", label = "", value = 0),
actionButton("answer", "Answer"),
actionButton("question", "New Question"),
)
server <- function(input, output, session) {
data <- reactiveValues(number = NULL)
output$out <- renderText({
if (is.null(data$number))
"Press 'New Question' button"
else
paste("Enter", data$number)
})
observeEvent(input$question, {
data$number = sample(10, 1)
})
observeEvent(input$answer, {
req(data$number, input$inn)
if (data$number == input$inn)
print("Correct")
# Do something exciting
else
print("Incorrect")
# Do something else
})
}
shinyApp(ui,server)
IMO it's good practice to keep reactive data and input/output generation separate. What I mean by that is that in the above example we use
reactiveValues to keep track of the changing data, and
observeEvent to monitor button clicks which may change specific elements of our reactive data,
renderText can print either fixed text or reactive data.