Wrap a reactive UI in an action button RShiny - r

Question

I have a tabbed UI that shows up whenever the user selects rows in a datatable (in the following code, the outputs are random, in real life the calculation is quite involved).
I would like to condition the tabbed UI showing up to the click of a button. Currently every time you select an additional row, it does the calculation all over again for the already selected rows. I would like to limit that to a one-time calculation when the user is done selecting all the rows he wants to see.
library(shiny)
library(DT)
The UI : the table, the action button and the tabbed section.
ui <- fluidPage(
mainPanel(
fluidRow(
column(12,DT::dataTableOutput(outputId = 'tableCurrencies'))
),
actionButton(inputId = 'showSelectedButton',label = 'Show Selec'),
fluidRow(
uiOutput("myTabUI")
)
)
)
The server function : If I remove the output$myTabUI <- eventReactive(input$launchCalcButton, { part and instead do output$myTabUI <- renderUI ({ ... directly it works as intended (minus the calculation following click on the button of course).
server <- function(input,output){
output$tableCurrencies <- DT::renderDataTable({datatable(data.frame(a=rnorm(10),b=rnorm(10),c=rnorm(10)))})
origTable_selected <- reactive({
ids <- input$tableCurrencies_rows_selected
return(ids)
})
output$myTabUI <- eventReactive(input$launchCalcButton, {
selectedTabs <- renderUI({
myTabs <- lapply(origTable_selected(),function(i) {
tabName <- paste0("test",i)
a <- renderPlot({
hist(rnorm(50))
})
output[[paste0(tabName,"rates")]] <- a
return(tabPanel(
tabName,
fluidRow(
column(6,plotOutput(paste0(tabName,"rates")))
)
))
})
return(do.call(tabsetPanel,myTabs))
})
selectedTabs
})
}
app = shinyApp(ui,server)
runApp(app,port=3250,host='0.0.0.0')
Not sure how to go about fixing this. Any help welcome.

Answer 1

You can use isolate() to limit reactive dependencies
library(shiny)
library(DT)
ui <- fluidPage(
mainPanel(
fluidRow(
column(12,DT::dataTableOutput(outputId = 'tableCurrencies'))
),
actionButton(inputId = 'showSelectedButton',label = 'Show Selec'),
fluidRow(uiOutput("myTabUI"))
)
)
server <- function(input,output){
output$tableCurrencies <- DT::renderDataTable({
data.frame(a=rnorm(10),b=rnorm(10),c=rnorm(10))})
origTable_selected <- reactive({
input$tableCurrencies_rows_selected
})
output$myTabUI <- renderUI({
input$showSelectedButton
myTabs <- lapply(isolate(origTable_selected()),function(i) {
tabName <- paste0("test",i)
a <- renderPlot({hist(rnorm(50))})
output[[paste0(tabName,"rates")]] <- a
return(tabPanel(
tabName,
fluidRow(column(6,plotOutput(paste0(tabName,"rates"))))
))
})
do.call(tabsetPanel,myTabs)
})
}
shinyApp(ui,server)