Run only relevant observe functions for each tab in shinyapp - r

Question

In my shiny app I have several tabs as follows.
I have little complex functions running in this app. I think all the observe functions in the server function run when anything is done in any tab. So I need to run only relevant observe functions for relevant tab. As an example, when I am in Summary tab only the relevant observe function should run and all the other observe functions should not run. I have a code.
server <- function(input, output) {
summary <- observe({....})
occupancy<- observe({....})
Bookings<- observe({....})
Maps<- observe({....})
}
Is there any modification to the above code to run only the relevant observe function related to the tab opened in the app.?

Answer 1

Some approaches come to mind. But first; what do you want to do in your observers? If you are simply creating output to display to the user, don't forget to use reactive elements. They will automatically invalidate only when their output is used to display something to the user. Thus if reactive X uses input Y used to construct output for tab A, and input Y changes while we are looking at tab B, reactive X will not invalidate.
If you are using your observers to only create side-effects, such as updating inputs or showing modalDialogs, you could:
use observeEvent instead of observe to only listen to changes in a certain input or condition.
use isolate to make isolate certain dependencies.
build an if-statement in your observer, that checks which tab is selected. You can do that by giving your sidebarMenu an id (my_sidebarmenu in the example below), and check which tab is selected inside your observer by calling input$my_sidebarmenu.
Some examples given below, how this helps~
#UI.R
#loading shiny library
library(shiny)
library(shinydashboard)
ui <- dashboardPage(
dashboardHeader(),
dashboardSidebar(
sidebarMenu(id='my_sidebarmenu',
menuItem('Tab 1', tabName='tab1'),
menuItem('Tab 2', tabName='tab2'),
actionButton(inputId = 'btn','Press me!')
)
),
dashboardBody(
tabItems(
tabItem('tab1',
p('Tab 1'),
actionButton('btn_tab1','Show message!')),
tabItem('tab2',
p('Tab 2'),
actionButton('btn_tab2','Show message!'))
)
)
)
server <- function(input, output,session)
{
observeEvent(input$btn,
{
if(input$my_sidebarmenu=='tab1')
{
updateTabItems(session,'my_sidebarmenu',selected='tab2')
}
if(input$my_sidebarmenu=='tab2')
{
updateTabItems(session,'my_sidebarmenu',selected='tab1')
}
})
observeEvent(input$btn_tab1,
{
showModal(modalDialog(
title = "One.",
"You are viewing tab 1!",
easyClose = TRUE,
footer = NULL
))
})
observeEvent(input$btn_tab2,
{
showModal(modalDialog(
title = "Two.",
"You are viewing tab 2!",
easyClose = TRUE,
footer = NULL
))
})
}
shinyApp(ui,server)