refresh the main panel screen in shiny using the action button - r

Question

I am building a shiny app and I want to refresh the main panel screen. Here is a sample code. I have a submit button to display the data and I have a re-fresh button to clear the screen. I am not so sure how to code the re-fresh button in R and shiny since I am new to this. Thanks for looking into
library(DT)
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
selectInput("amountTable", "Amount Tables", 1:10),
actionButton("submit1" ,"Submit", icon("refresh"),
class = "btn btn-primary"),
actionButton("refresh1" ,"Refresh", icon("refresh"),
class = "btn btn-primary")
),
mainPanel(
# UI output
uiOutput("dt")
)
)
)
server <- function(input, output, session) {
observeEvent(input$submit1, {
lapply(1:input$amountTable, function(amtTable) {
output[[paste0('T', amtTable)]] <- DT::renderDataTable({
iris[1:amtTable, ]
})
})
})
output$dt <- renderUI({
tagList(lapply(1:10, function(i) {
dataTableOutput(paste0('T', i))
}))
})
}
shinyApp(ui, server)

Answer 1

You could add the possibility of return nothing from the renderUI() if the refresh button is used.
As it is not that straightforward to reset an action button you would have to use a workaround with a reactive variable.
if(global$refresh) return()
This reactive variable you can control with the refresh and submit button
E.g. if(input$refresh1) isolate(global$refresh <- TRUE)
which you wrap in seperate observe functions.
Full code see below:
library(DT)
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
selectInput("amountTable", "Amount Tables", 1:10),
actionButton("submit1" ,"Submit", icon("refresh"),
class = "btn btn-primary"),
actionButton("refresh1" ,"Refresh", icon("refresh"),
class = "btn btn-primary")
),
mainPanel(
# UI output
uiOutput("dt")
)
)
)
server <- function(input, output, session) {
global <- reactiveValues(refresh = FALSE)
observe({
if(input$refresh1) isolate(global$refresh <- TRUE)
})
observe({
if(input$submit1) isolate(global$refresh <- FALSE)
})
observeEvent(input$submit1, {
lapply(1:input$amountTable, function(amtTable) {
output[[paste0('T', amtTable)]] <- DT::renderDataTable({
iris[1:amtTable, ]
})
})
})
output$dt <- renderUI({
if(global$refresh) return()
tagList(lapply(1:10, function(i) {
dataTableOutput(paste0('T', i))
}))
})
}
shinyApp(ui, server)