Shiny: add button label to sidebar & update buttons after click - r

Question

I'm a bit rusty to Shiny reactivity, but I want to do two things when a button is clicked:
add that button label to the sidebar (and add more labels to sidebar after more clicks)
update the button labels (i.e. more random integers)
I'm nervous about changing the label before recording it, so I want to get the timing right. Here's a skeleton of what I'm working with:
library(shiny)
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
textOutput("clicks")
),
mainPanel(
uiOutput("button1"),
uiOutput("button2")
))
)
###################
server <- function(input, output, session) {
output$clicks <- renderText({
paste()
})
## reactive values
inside <- reactive({
inside <- sample(1:100,2)
})
## buttons
output$button1 <- renderUI({
actionButton("course1", label = inside()[1], style='padding:50px')
})
output$button2 <- renderUI({
actionButton("course2", label = inside()[2], style='padding:50px')
})
}
shinyApp(ui = ui, server = server)
Right now the sidebar is blank because I'm not sure how to add it, or what to add to make the button labels update after a click (whether to do it inside a reactive value or an observeEvent). Any help is much appreciated!

Answer 1

Here's a way to do it with reactiveValues:
library(shiny)
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
textOutput("clicks")
),
mainPanel(
uiOutput("button1"),
uiOutput("button2")
))
)
###################
server <- function(input, output, session) {
# Show history
output$clicks <- renderText({
history[['clicked']]
})
## reactive values
# store history as reactive values
history <- reactiveValues(clicked = c())
# update history when a button is clicked
observeEvent(input$course1,{
history[['clicked']] <- c(history[['clicked']],inside()[1])
})
observeEvent(input$course2,{
history[['clicked']] <- c(history[['clicked']],inside()[2])
})
#update inside when history updates
inside <- reactive({
history[['clicked']]
inside <- sample(1:100,2)
})
## buttons
output$button1 <- renderUI({
actionButton("course1", label = inside()[1], style='padding:50px')
})
output$button2 <- renderUI({
actionButton("course2", label = inside()[2], style='padding:50px')
})
}
shinyApp(ui = ui, server = server)