Shiny - observeEvent appears without click

I would like to develop an application with two buttons :
1. Calculate
2. Refresh

When I click on the button "Calculate", a second button appears. When I click on the second button, a sentence appears : "Le resultat est...". The button refresh clean the web page. Now the page is clean and only the two initial buttons appears : Calculate and Refresh.

If i click another time on the button Calculate, the sentence "Le resultat est..." appears without click on the second button.

Question : How can i do obtain the sentence "Le resultat est..." only after a click on the second button ?

Below my code :

library(shiny)
data_Modele <- deval_Shiny

ui <- fluidPage(
actionButton("runif", "Uniform"),
actionButton("reset", "Clear"),
uiOutput("plot")
)

server <- function(input, output){

v <- reactiveValues(data = NULL)

observeEvent(input$runif, {
v$data <- round(runif(1, min=1, max=nrow(deval_Shiny)),digits = 0)

output$Button<- renderUI({
actionButton("button", "click me")
})
})

observeEvent(input$reset, {
v$data <- NULL
})

observeEvent(input$button, {
output$Reponse <- renderText(paste0("Le resultat est :",v$data))
})


output$plot <- renderUI({
if (is.null(v$data)) return()

tagList(
uiOutput("Button"),
uiOutput("Reponse")
)
})
}

shinyApp(ui, server)


Thank you in advance for your help :)

J.

2 Answers
2

If you want your uiOutputs to behave separately, I would suggest not to bind them together inside output$plot. So if you don't need them to be together, I would add a variable show_response to control whether you want to display the response or not.

uiOutputs

output$plot

show_response

library(shiny)

ui <- fluidPage(
actionButton("runif", "Uniform"),
actionButton("reset", "Clear"),
uiOutput("Button"),
uiOutput("Reponse")
)

server <- function(input, output){

v <- reactiveValues(data = NULL)
show_response <- reactiveValues(state = FALSE)

observeEvent(input$runif, {
v$data <- round(runif(1, min = 1, max = 100), digits = 0)
})

observeEvent(input$reset, {
v$data <- NULL
show_response$state <- FALSE
})

observeEvent(input$button, {
show_response$state <- TRUE
})

output$Button <- renderUI({
req(v$data)
actionButton("button", "click me")
})

output$Reponse <- renderText({
req(show_response$state)
paste0("Le resultat est :", v$data)
})

}

shinyApp(ui, server)


Thank you very much
– Jeremy Bergeret
Jun 29 at 11:12

You can use shinyjs and its show and hide functions:

shinyjs

show

hide

library(shiny)
library(shinyjs)

deval_Shiny <- mtcars
data_Modele <- deval_Shiny

ui <- fluidPage(
useShinyjs(),
actionButton("runif", "Uniform"),
actionButton("reset", "Clear"),br(),
actionButton("button", "click me"),
textOutput("Reponse")
)

server <- function(input, output){

observe({
hide("button")
hide("Reponse")
})

v <- reactiveValues(data = NULL)

observeEvent(input$runif,{
show("button")
v$data <- round(runif(1, min=1, max=nrow(deval_Shiny)),digits = 0)
})

observeEvent(input$reset, {
hide("button")
hide("Reponse")
})

output$Reponse <- renderText(paste0("Le resultat est :",v$data))

observeEvent(input$button, {
show("Reponse")
})
}

shinyApp(ui, server)


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