How to disable one button in a Shiny actionGroupButtons input - r

Question

The toy app in the example below contains an R/Shiny actionGroupButtons element. I am looking for guidance please on how to start the actionGroupButtons with button ‘btn_edit’ disabled, which can then become enabled on a click of the button ‘btn_enable’.
Button ‘btn_duplicate’ should remain enabled at all times.
#DeanAttali mentions the use of the ‘disabled’ attribute here (Shiny: how to start application with action button disabled?), though I think that it is one of the inputs that it doesn’t work with.
Any ideas please? TIA
library(shiny)
library(shinyWidgets)
library(shinyjs)
ui <- fluidPage(
useShinyjs(),
fluidRow(
actionGroupButtons(
inputIds = c("btn_edit", "btn_duplicate"),
labels = list("Edit", "Duplicate")
)
),
br(),
fluidRow(
actionButton('btn_enable', 'enable edit')
),
br(),
fluidRow(
verbatimTextOutput('btns')
),
br(),
fluidRow(
verbatimTextOutput('btn_enable')
)
)
server <- function(input, output) {
observeEvent((input$btn_edit|input$btn_duplicate),{
output$btns <- renderPrint({paste(input$btn_edit, 'and', input$btn_duplicate)})
})
observeEvent(input$btn_enable,{
output$btn_enable <- renderPrint({input$btn_enable})
if(input$btn_enable > 0) {
shinyjs::enable("btn_edit")
} else {
shinyjs::disable("btn_edit")
}
}, ignoreInit = TRUE)
}
shinyApp(ui = ui, server = server)

Answer 1

You need to set ignoreNULL = FALSE in your observeEvent call, otherwise it will run only after btn_enable was pressed:
library(shiny)
library(shinyWidgets)
library(shinyjs)
ui <- fluidPage(
useShinyjs(),
fluidRow(
actionGroupButtons(
inputIds = c("btn_edit", "btn_duplicate"),
labels = list("Edit", "Duplicate")
)
),
br(),
fluidRow(
actionButton('btn_enable', 'enable edit')
),
br(),
fluidRow(
verbatimTextOutput('btns')
),
br(),
fluidRow(
verbatimTextOutput('btn_enable')
)
)
server <- function(input, output, session) {
observeEvent((input$btn_edit|input$btn_duplicate),{
output$btns <- renderPrint({paste(input$btn_edit, 'and', input$btn_duplicate)})
})
observeEvent(input$btn_enable, {
output$btn_enable <- renderPrint({input$btn_enable})
if(input$btn_enable > 0) {
shinyjs::enable("btn_edit")
} else {
shinyjs::disable("btn_edit")
}
}, ignoreInit = FALSE, ignoreNULL = FALSE)
}
shinyApp(ui = ui, server = server)
Another approach would be to disable the button outside of the observer:
library(shiny)
library(shinyWidgets)
library(shinyjs)
ui <- fluidPage(
useShinyjs(),
fluidRow(
actionGroupButtons(
inputIds = c("btn_edit", "btn_duplicate"),
labels = list("Edit", "Duplicate")
)
),
br(),
fluidRow(
actionButton('btn_enable', 'enable edit')
),
br(),
fluidRow(
verbatimTextOutput('btns')
),
br(),
fluidRow(
verbatimTextOutput('btn_enable')
)
)
server <- function(input, output, session) {
shinyjs::disable("btn_edit")
observeEvent((input$btn_edit|input$btn_duplicate),{
output$btns <- renderPrint({paste(input$btn_edit, 'and', input$btn_duplicate)})
})
observeEvent(input$btn_enable, {
output$btn_enable <- renderPrint({input$btn_enable})
shinyjs::enable("btn_edit")
})
}
shinyApp(ui = ui, server = server)